Recycling method for positive electrode of waste battery

Abstract

The present application provides a recycling method, which is used for recycling valuable metals in positive electrode powder of waste batteries. Sulfuric acid produced by an electrolysis reaction can be used to continue dissolving more positive electrode powder in a slurry until the sulfuric acid is almost depleted and electrolysis ends. This self-sustaining process can reduce the usage of sulfuric acid in an extraction process. Furthermore, during extraction of metals such as nickel and cobalt in the slurry, the concentration of a first metal element remaining in the slurry is increased, such that extraction of the first metal element becomes possible and efficient. In addition, the recycling method provided by the present application can also perform continuous electrolysis treatment, and, as sulfuric acid generated by electrolysis or supplemental sulfuric acid can dissolve more positive electrode powder, the recycling rate and productivity are improved. Thus, the entire recycling process is simple, economical and efficient; by means of reducing the usage of acid and alkali, the recycling method reduces the impact on the environment, thereby being environment-friendly.

Description

A method for recycling the positive electrode of a waste battery

[0001] This application claims priority to Chinese Patent Application No. 202411043791.6, filed on July 31, 2024, entitled "A Method for Recycling the Positive Electrode of a Waste Battery"; Chinese Patent Application No. 202411043810.5, filed on July 31, 2024, entitled "A Method for Recycling the Positive Electrode of a Waste Battery"; and Chinese Patent Application No. 202411043826.6, filed on July 31, 2024, entitled "A Method for Recycling the Positive Electrode of a Waste Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery recycling technology, and in particular to a method for recycling the positive electrode of a waste battery. Background Technology

[0003] With the continuous expansion of the electric vehicle and renewable energy markets, new energy batteries, as an important energy storage device, have been widely used in automobiles, power tools, mobile devices, and other fields due to their high energy density and long lifespan. However, the recycling and disposal of used batteries remains a global challenge. Once batteries are damaged or reach the end of their lifespan, a large number of used batteries are generated, posing potential pollution and resource waste problems to the environment. Therefore, developing an efficient and environmentally friendly recycling method is crucial.

[0004] Traditional recycling processes mainly include pyrometallurgy and hydrometallurgy. Pyrometallurgy extracts valuable metals or compounds from cathode materials through high-temperature treatment. While the process is simple, it has low recovery efficiency and product quality, and easily generates harmful gases that pollute the environment. Hydrometallurgy involves pre-treating the cathode material and then using processes such as acid leaching and extraction to enrich the valuable metals for recovery or utilization. These methods generally use large amounts of acids, alkalis, and extraction solutions, increasing recycling costs and resulting in low processing efficiency, making large-scale industrialization impossible.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a method for recycling the positive electrode of waste batteries, which reduces the amount of sulfuric acid used in the recycling process, lowers recycling costs, and allows for continuous electrolysis through a refueling method. The specific technical solution is as follows:

[0007] The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0008] (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder;

[0009] (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry, the slurry containing a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone the dissolution reaction;

[0010] (3) The slurry is subjected to electrolytic treatment, and at least the positive electrode powder and the reducing agent are added to the slurry during the electrolytic treatment process;

[0011] The electrolytic treatment produces sulfuric acid, which then undergoes a dissolution reaction with the added positive electrode powder and the reducing agent.

[0012] (4) The electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry.

[0013] The cathode products include nickel and / or cobalt.

[0014] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0015] In some embodiments of this application, in step (2), the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

[0016] In some embodiments of this application, the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0017] In some embodiments of this application, step (3), adding at least the positive electrode powder and the reducing agent to the slurry, includes adding the positive electrode powder and the reducing agent to the slurry.

[0018] In some embodiments of this application, step (3), which involves adding at least the positive electrode powder and the reducing agent to the slurry, includes adding the positive electrode powder, the reducing agent, and sulfuric acid to the slurry.

[0019] In some embodiments of this application, in step (3), the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0020] In some embodiments of this application, in step (3), the positive electrode powder, the reducing agent and sulfuric acid are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0021] In some embodiments of this application, steps (2) and (3) include:

[0022] (2) The slurry is obtained by mixing at least the positive electrode powder, sulfuric acid, the reducing agent, and water and carrying out a dissolution reaction. The temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

[0023] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

[0024] In some embodiments of this application, the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0025] When the mass of nickel and / or cobalt in the cathode product increases by m1, the cathode powder and the reducing agent are added.

[0026] Where m1≤0.1m0.

[0027] In some embodiments of this application, 0.0001m0 ≤ m1 ≤ 0.1m0;

[0028] m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0029] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1;

[0030] The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0031] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

[0032] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, the reducing agent, and sulfuric acid are added during the electrolysis process.

[0033] In some embodiments of this application, sulfuric acid is added when the mass of nickel and / or cobalt in the cathode product increases by m1; wherein m1 ≤ 0.1m0.

[0034] In some embodiments of this application, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0035] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7; wherein, when the reducing agent does not contain S element, the following condition is satisfied: 0.9×(0.5N5+0.5N7)≤N6≤1.1×(0.5N5+0.5N7).

[0036] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7; when the reducing agent contains sulfur, the total number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9×(0.5N5+0.5N7)≤N8+N6≤1.1×(0.5N5+0.5N7); wherein, the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0037] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0038] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0039] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; wherein, when the reducing agent does not contain S element, the following condition is satisfied: 0.9×(0.5P1+P2+0.5P4)≤ P3≤1.1×(0.5P1+P2+0.5P4).

[0040] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; when the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4); wherein, the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0041] In some embodiments of this application, the electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element, and the filtrate is purified to obtain salt containing the first metal element.

[0042] In some embodiments of this application, the filter residue is added to the slurry for further electrolytic treatment.

[0043] In some embodiments of this application, the first metal element is selected from sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element.

[0044] In some embodiments of this application, the concentrated mother liquor is added to the slurry for further electrolytic treatment.

[0045] In some embodiments of this application, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition, wherein the filtrate, after carbonization deposition, yields at least a lithium-containing salt and a deposition mother liquor.

[0046] In some embodiments of this application, the sedimentation mother liquor is added to the slurry for further electrolytic treatment.

[0047] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0048] In some embodiments of this application, in step (3), the anode and cathode in the electrolytic process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0049] In some embodiments of this application, in step (4), the anode product includes manganese dioxide.

[0050] In some embodiments of this application, in step (1), the waste battery is disassembled to obtain the positive electrode, and the positive electrode is pretreated to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0051] In step (2), at least the positive electrode powder, sulfuric acid, reducing agent, and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone a dissolution reaction. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite.

[0052] In step (3), the slurry is subjected to electrolytic treatment, and during the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to the slurry; step (4) further includes the following steps:

[0053] (4.1) When the preset conditions are met, a portion of the electrolyzed slurry is discharged, and the discharged electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element; wherein, the electrolyzed slurry is an electrolysis slurry;

[0054] The preset condition is 0.7C2≤C1<C2.

[0055] Wherein, the concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C1, and the theoretical saturation concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C2.

[0056] (4.2) The filtrate containing the first metal element is purified to obtain salt and mother liquor containing the first metal element. The mother liquor is returned to the slurry in step (3) for further electrolysis.

[0057] In some embodiments of this application, when the preset conditions are met, the volume of the slurry discharged from the electrolysis is V1, and the volume of the mother liquor returned to step (3) is V2, where 0.95V1≤V2<V1.

[0058] In some embodiments of this application, the volume of the slurry in step (2) is V3, where V1 ≤ 0.2V3.

[0059] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0060] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0061] In some embodiments of this application, step (3) involves adding at least the positive electrode powder and the reducing agent to the slurry, including adding the positive electrode powder and the reducing agent to the slurry.

[0062] In some embodiments of this application, step (3) involves adding at least the positive electrode powder and the reducing agent to the slurry, including adding the positive electrode powder, the reducing agent, and sulfuric acid to the slurry.

[0063] In some embodiments of this application, in step (3), the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0064] In some embodiments of this application, in step (3), the positive electrode powder, the reducing agent and sulfuric acid are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0065] In some embodiments of this application, the recycling method includes the following steps: steps (2) and (3) include:

[0066] A slurry is obtained by mixing at least the aforementioned positive electrode powder, sulfuric acid, reducing agent, and water and then dissolving them. The slurry contains a solid phase and a liquid phase, wherein the solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The dissolution temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the mixed slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite.

[0067] The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

[0068] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt in the cathode product increases by m1 during the electrolysis process, the cathode powder and the reducing agent are added; wherein, m1≤0.1m0.

[0069] In some embodiments of this application, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0070] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1;

[0071] The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0072] In some embodiments of this application, the reducing agent is sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

[0073] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, the reducing agent, and sulfuric acid are added during the electrolysis process.

[0074] In some embodiments of this application, sulfuric acid is added when the mass of nickel and / or cobalt in the cathode product increases by m1 during the electrolysis process; wherein m1 ≤ 0.1m0.

[0075] In some embodiments of this application, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0076] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7; wherein, when the reducing agent does not contain S element, the following condition is satisfied: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7).

[0077] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7; when the reducing agent contains sulfur, the total number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7); wherein, the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0078] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide; or, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0079] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; wherein, when the reducing agent does not contain S element, the following condition is satisfied: 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4).

[0080] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; when the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 + P5 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); wherein, the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0081] In some embodiments of this application, the first metal element is selected as sodium or lithium, the purification process is concentration and crystallization, the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element; the concentrated mother liquor is returned to the slurry in step (3) for further electrolytic treatment.

[0082] In some embodiments of this application, the first metal element is lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate is then carbonized to obtain a lithium-containing salt, a nickel-containing and / or cobalt-containing salt, and a mother liquor.

[0083] The salt containing nickel and / or cobalt and the mother liquor of the deposition are returned to the slurry in step (3) for further electrolytic treatment.

[0084] In some embodiments of this application, the mother liquor is desodiumed and then returned to the slurry in step (3) for further electrolysis.

[0085] In some embodiments of this application, the mother liquor is evaporated and concentrated before being added to the slurry in step (3) for further electrolysis, and / or, water is added to the slurry during electrolysis.

[0086] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0087] In some embodiments of this application, in step (3), the anode and cathode in the electrolytic process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0088] In some embodiments of this application, the electrolysis process continues without interruption.

[0089] In some embodiments of this application, in step (1), the waste battery is disassembled to obtain the positive electrode, and the positive electrode is pretreated to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0090] In step (2), at least the positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone a dissolution reaction.

[0091] The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite;

[0092] In step (3), the slurry is subjected to electrolytic treatment, during which the positive electrode powder and the reducing agent are added to the slurry.

[0093] Step (4) also includes the following steps:

[0094] (4.3) When the preset conditions are met, the electrolysis process is stopped to obtain the anode product, the cathode product and the electrolyzed slurry;

[0095] The cathode product includes nickel and / or cobalt, and the electrolytically treated slurry is the slurry after the electrolysis is completed;

[0096] Wherein, the reducing agent is selected from sulfur dioxide, and the preset condition is: during the electrolysis process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation; or...

[0097] The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the preset condition is any one of the following:

[0098] (a) During the electrolytic treatment process, the ion concentration of the second metal element in the slurry is less than or equal to 0.05 wt%;

[0099] (b) During the electrolytic treatment, the current density is less than or equal to 8 mA / cm². 2 ;

[0100] (c) During the electrolytic treatment process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation.

[0101] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0102] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0103] In some embodiments of this application, step (2) includes:

[0104] A slurry is prepared by mixing at least the aforementioned positive electrode powder, sulfuric acid, reducing agent, and water and reacting them to obtain a slurry containing a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

[0105] In some embodiments of this application, in step (3), the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0106] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt added to the cathode product is m1, the cathode powder and the reducing agent are added; wherein, m1≤0.1m0.

[0107] In some embodiments of this application, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0108] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1;

[0109] The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0110] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0111] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0112] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; wherein, when the reducing agent does not contain S element, the following condition is satisfied: 0.9╳(0.5P1+P2+0.5P4)≤P3≤1.1╳(0.5P1+P2+0.5P4).

[0113] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; when the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9╳(0.5P1+P2+0.5P4)≤P3+P5≤1.1╳(0.5P1+P2+0.5P4); wherein, the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0114] In some embodiments of this application, after the electrolysis is completed, the slurry is filtered to obtain filter residue and filtrate containing the first metal element, and the filtrate is purified to obtain salt containing the first metal element; in some embodiments of this application, the filter residue is added to the next slurry for further electrolysis.

[0115] In some embodiments of this application, the first metal element is selected as sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element.

[0116] In some embodiments of this application, the concentrated mother liquor is added to the next slurry for further electrolysis.

[0117] In some embodiments of this application, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate is subjected to carbonization deposition to obtain a lithium-containing salt and a deposition mother liquor. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide.

[0118] In some embodiments of this application, the sedimentation mother liquor is added to the next slurry for further electrolytic treatment.

[0119] In some embodiments of this application, in step (4.3), the anode product comprises manganese dioxide.

[0120] In some embodiments of this application, the preset condition is that the concentration of the salt corresponding to the first metal element in the slurry reaches saturation, satisfying the condition 0.95n≤m≤n;

[0121] Wherein, the theoretical saturation concentration of the salt corresponding to the first metallic element in the slurry is n.

[0122] The actual concentration of the salt corresponding to the first metallic element in the slurry is m.

[0123] The beneficial effects of this application are:

[0124] The recycling method provided in this application is used to recover valuable metals, namely first and second metallic elements, from the positive electrode powder of spent batteries. The second metallic element, such as nickel and cobalt, contained in the acidic slurry is separated by electrolysis. The sulfuric acid produced by the electrolysis reaction can be used to further dissolve more positive electrode powder in the slurry; this self-sustaining process reduces the use of sulfuric acid in the extraction process. The method provided in this process allows electrolysis to continue through a feeding mechanism, for example, by feeding to allow electrolysis to continue for a period of time and then stop; or, for example, by feeding to allow electrolysis to continue without stopping. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and effective. In addition, the recycling method provided in this application allows for continuous electrolysis through feeding, because the sulfuric acid produced by electrolysis or the added sulfuric acid can dissolve more positive electrode powder, thereby improving the recovery rate and production capacity. The recycling method provided in this process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method.

[0125] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0126] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0127] Figure 1 is an experimental flowchart of Examples 1-1 and 3-1;

[0128] Figure 2 is an experimental flowchart of Examples 1-2 and 3-2;

[0129] Figure 3 is an experimental flowchart of Examples 1-3 and Examples 2-2;

[0130] Figure 4 is an experimental flowchart of Examples 1-5 and Examples 2-4. Detailed Implementation

[0131] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0132] In this process, the dissolution and electrolysis of the cathode powder take place in the same electrolytic cell / container or connected containers. This allows the H2SO4 generated during electrolysis to continuously dissolve newly added cathode powder, ensuring full utilization of sulfuric acid and reducing acid consumption. The amount of sulfuric acid used in this process is significantly reduced compared to traditional processes. Specifically, in traditional recovery processes, when sulfuric acid is used, elements such as Li, Na, Co, Ni, and Mn in the cathode powder all need to react with SO4. 2- The recovery of elements requires a combination of factors. If we consider sulfur (S) as an example, 2 mol of Li corresponds to 1 mol of S, 2 mol of Na corresponds to 1 mol of S, and 1 mol of Co (or Ni or Mn) corresponds to 1 mol of S. In other words, the molar amount of S needs to match the total molar amount of Li, Na, Co, Ni, and Mn. Therefore, a large amount of sulfuric acid is consumed during the recovery process, increasing the recovery cost. However, in this process, only the molar amount of S corresponding to the molar amount of Li is needed, thus reducing the overall demand for S, or in other words, reducing the demand for sulfuric acid or acidic substances. Based on this, this application provides a method for recycling the positive electrode of waste batteries to reduce the amount of sulfuric acid used in the recycling process and lower the recycling cost.

[0133] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0134] (1) Disassemble waste batteries to obtain positive electrodes, and pre-treat the positive electrodes to obtain positive electrode powder;

[0135] (2) At least positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction.

[0136] (3) Electrolyze the slurry and add at least positive electrode powder and reducing agent to the slurry during the electrolysis process; wherein, sulfuric acid is generated during the electrolysis process, and the sulfuric acid continues to react with the added positive electrode powder and reducing agent to dissolve;

[0137] (4) Electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry, wherein the cathode product includes nickel and / or cobalt.

[0138] In some embodiments of this application, the cathode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese.

[0139] The recycling method provided in this application involves carrying out the dissolution reaction and electrolysis process in the same or connected containers. On one hand, by adding positive electrode powder and a reducing agent, the sulfuric acid generated during the electrolysis process can continuously dissolve the added positive electrode powder in the slurry, allowing the dissolution reaction and electrolysis to proceed simultaneously, thus increasing the amount of positive electrode powder that can be processed. On the other hand, because sulfuric acid is generated during the electrolysis process, the actual consumption of SO4 is reduced. 2- SO4 consumed only by the first metallic element in the cathode powder 2- That is, the overall reaction only needs to provide Li + Required SO4 2- That is, compared to traditional recycling processes that simultaneously consume both the first and second metal elements (SO4), 2- Technical solution: The SO4 recycling method of this application 2- The consumption of sulfuric acid is greatly reduced, thus reducing the demand for sulfuric acid. Consequently, the amount of sulfuric acid required throughout the recycling process is significantly reduced, lowering recycling costs. Furthermore, no harmful gases are generated during the entire recycling process, making it an environmentally friendly recycling method.

[0140] In this process, pretreated positive electrode powder, sulfuric acid and reducing agent are mixed and dissolved to form a slurry. The slurry contains a solid phase (i.e. undissolved positive electrode powder) and a liquid phase composed of various substances obtained after the dissolution reaction, sulfuric acid, water and so on.

[0141] In this application, a certain solid phase is always required in the slurry to avoid H+ precipitates due to the different rates of dissolution and electrolysis reactions. + The accumulation of [something] prevents electrolysis from occurring if the pH value is below the expected range.

[0142] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5. For example, the solid content W1 of the slurry can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or 6.5, or between any two of the above numbers.

[0143] By adjusting the pH of the slurry in step (2) within the above-mentioned range, the electrolysis process can proceed stably, because excessively high or low pH values ​​during electrolysis will affect the normal operation of the electrolysis process. For example, if the pH value is too low, H2 gas is easily generated during electrolysis, which will affect the electrolysis production of elemental metals; if the pH value is too high, there is a risk that the metal elements will form alkaline precipitates, which will also affect the normal operation of the electrolysis process.

[0144] By controlling the solid content W1 of the slurry in step (2) within the above range, the H+ content can be prevented from increasing due to the continuous generation of sulfuric acid during subsequent electrolytic treatment. + The accumulation of these deposits can then affect subsequent electrolytic processing.

[0145] Specifically, because the pH value needs to be within the range of 2 to 6.5 during electrolysis, and the electrolysis reaction often occurs rapidly, a large amount of H2SO4 (H+) can be produced in a short period of time. + The dissolution reaction is relatively slow. In this process, electrolysis is continued by feeding materials, and the slurry must always have a certain solid content. This is because if the cathode powder is completely dissolved throughout the process, the difference in reaction rates between the two reactions will result in a higher H₂ content during electrolysis. + Unable to react with the positive electrode powder in time, resulting in H + Excessive accumulation causes the pH of the electrolytic slurry to drop, making it unsuitable for electrolysis (at which point the electrolysis product is H2 instead of metal), and electrolysis cannot continue. Conversely, when the slurry contains some undissolved cathode powder, although the dissolution reaction rate is still slow, the increased amount of reactants results in a higher H2 consumption per unit time. + Increasing the pH level can keep the slurry pH within the required range, allowing electrolysis to continue.

[0146] In some embodiments of this application, in step (2), the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide. The conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h. For example, the temperature T1 of the dissolution reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the time t1 of the dissolution reaction can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. By controlling the temperature T1 and time t1 of the dissolution reaction within the above range, it is beneficial to fully dissolve the cathode powder to obtain the slurry with the desired solid content.

[0147] In some embodiments of this application, in step (2), the sulfuric acid is commercially available concentrated sulfuric acid.

[0148] In some embodiments of this application, the cathode material includes LiMO2 or NaMO2, where M is selected from at least one of Ni, Co, and Mn. When the cathode material includes LiMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of Li2SO4, NiSO4, CoSO4, MnSO4, H2O, and H2SO4. When the cathode material includes NaMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of NiSO4, CoSO4, MnSO4, H2O, H2SO4, and Na2SO4.

[0149] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0150] Specifically, when the reducing agent does not contain sulfur (S), that is, the reducing agent is selected from hydrogen peroxide. It satisfies 0.9×(0.5P1+P2+0.5P4)≤ P3≤1.1×(0.5P1+P2+0.5P4). For example, P3 can be 0.9×(0.5P1+P2+0.5P4), 0.92×(0.5P1+P2+0.5P4), 0.94×(0.5P1+P2+0.5P4), 0.95×(0.5P1+P2+0.5P4), 0.96×(0.5P1+P2+0.5P4), 0.98×(0.5P1+P2+0.5P4), 1× The formulas are (0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above values. By adjusting the relationship between P1, P2, P3, and P4 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0151] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, the molar number of S in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4). For example, P3+P5 can be 0.9×(0.5P1+P2+0.5P4), 0.92×(0.5P1+P2+0.5P4), 0.94×(0.5P1+P2+0.5P4), 0.95×(0.5P1+P2+0.5P4), 0.96×(0.5P1+P2+0.5P4), 0.98×(0.5P1+P2+0.5P4), 1 ×(0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above numbers. By adjusting the relationship between P1, P2, P3, P4, and P5 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0152] In this scheme, sulfuric acid is used to dissolve most of the positive electrode powder. The amount of sulfuric acid added is only enough to dissolve the preset amount of positive electrode powder that needs to be dissolved. A small portion of the positive electrode powder must remain undissolved (i.e., to ensure that a certain solid content is maintained in the slurry). This ensures that the dissolution reaction can be fully carried out during subsequent continuous feeding and electrolysis, avoids a decrease in the pH of the system, and keeps the pH within a suitable range during the electrolysis process, allowing the electrolysis to continue.

[0153] In some embodiments of this application, step (3) involves adding at least positive electrode powder and a reducing agent to the slurry, which is method one: adding positive electrode powder and a reducing agent to the slurry. In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, and the positive electrode powder and reducing agent are added during the electrolysis process. On the one hand, a) when SO2 is used as a reducing agent, it can also act as an "S" source, converting into SO4 during the electrolysis process. 2- This ensures that the overall system does not consume sulfuric acid. Therefore, during electrolysis, only positive electrode powder and reducing agent need to be added, without the need to add sulfuric acid, allowing the slurry electrolysis to continue (or stop after a period of time, or continue without stopping). Consequently, the demand for sulfuric acid is further reduced throughout the recovery process, resulting in lower recovery costs. b) When hydrogen peroxide, sodium sulfite, sodium thiosulfate, or sodium metabisulfite are used as reducing agents, the overall reaction only requires the consumption of the first metallic element, such as Li. + The corresponding SO4 2- Compared to existing technologies where the first and second metal elements simultaneously consume SO4, 2- The technical solution reduces the amount of sulfuric acid required (especially for reducing agents such as sodium sulfite, sodium thiosulfate, and sodium metabisulfite, where the sulfuric acid requirement is further reduced). However, for these reducing agents, since only positive electrode powder and reducing agent are added, subsequent electrolysis can continue for a period of time. Electrolysis stops when the sulfuric acid is nearly exhausted. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ in the sulfuric acid produced during electrolysis. + The reaction proceeds while maintaining the pH value within the range necessary for normal electrolysis. A pH value that is too high or too low will affect the normal operation of the electrolysis process. Therefore, in this process, the added positive electrode powder, reducing agent, and sulfuric acid generated during electrolysis continuously undergo dissolution and electrolysis reactions, consuming the H₂ produced during electrolysis. + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+The ratio is relatively stable. Therefore, by continuously adding positive electrode powder, reducing agent and sulfuric acid produced by electrolysis, the pH of the slurry electrolysis can be adjusted without adding alkali to adjust the pH of the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities.

[0154] In some embodiments of this application, step (3) involves adding at least positive electrode powder and a reducing agent to the slurry in a second manner: adding positive electrode powder, a reducing agent, and sulfuric acid to the slurry. In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and positive electrode powder, a reducing agent, and sulfuric acid are added during the electrolysis process. When the above-mentioned reducing agent is used, on the one hand, sulfuric acid will be generated during the electrolysis process, and on the other hand, as the electrolysis process proceeds, only the first metal element in the entire system will consume SO4. 2- This process consumes a portion of the sulfuric acid in the overall system. Replenishing this consumed sulfuric acid during electrolysis allows the electrolysis to continue uninterrupted. Of course, it also requires the replenishment of necessary positive electrode powder and reducing agent. However, since sulfuric acid is also generated during electrolysis, meaning only a portion of the sulfuric acid is consumed, the overall sulfuric acid requirement during the recovery process is relatively low compared to existing technologies that simultaneously consume SO4 from the first and second metal elements. 2- This technical solution reduces the demand for sulfuric acid and lowers recycling costs. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ in the sulfuric acid produced during electrolysis. + The reaction proceeds to ensure the pH value remains within the range necessary for normal electrolysis. A pH value that is too high or too low will negatively impact the electrolysis process. Therefore, this process utilizes the added positive electrode powder, reducing agent, and sulfuric acid to continuously undergo dissolution and electrolysis reactions with the sulfuric acid produced during electrolysis. This not only consumes the H₂ produced during electrolysis but also... + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable; moreover, by adding sulfuric acid, electrolysis can be carried out continuously without interruption. Thus, by continuously adding positive electrode powder, reducing agent, and sulfuric acid, the pH of the slurry electrolysis can be adjusted without the need to add alkali to adjust the pH of the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities, allowing the electrolysis process to continue without interruption.

[0155] In some embodiments of this application, in step (3), positive electrode powder and reducing agent are added, or positive electrode powder, reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.5. For example, the solid content W2 of the slurry can be maintained at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be maintained at 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 or 6.5, or between any two of the above numbers. During the electrolytic treatment process, the pH value of the slurry is maintained within the range of 2 to 6.5. The electrolytic reaction rate is relatively fast, and a large amount of H2SO4, i.e., H+, can be generated in a short period of time. + An increase in pH will decrease the pH value, and if the pH is too low, it will affect the electrolysis reaction rate. Generally, the dissolution reaction rate is slower than the electrolysis reaction rate. Therefore, to maintain the slurry solid content W2 within the range of 1 g / L to 50 g / L, the amount of H₂ consumed per unit time... + Increasing the concentration of the positive electrode powder, reducing agent, and optional sulfuric acid can maintain the slurry pH within the range of 2 to 6.5. This allows the dissolution and electrolysis reactions to continue, and also prevents the H+ from being reduced due to the continuous generation of sulfuric acid. + This accumulation can hinder the normal operation of the electrolytic process.

[0156] In some embodiments of this application, steps (2) and (3) include the following steps:

[0157] (2) A slurry is obtained by mixing at least positive electrode powder, sulfuric acid, a reducing agent, and water and carrying out a dissolution reaction. The dissolution reaction temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, or any other suitable reducing agent that can promote the dissolution of the positive electrode powder in sulfuric acid and / or the subsequent electrolytic reaction to extract the metal or metal compound. For example, the dissolution reaction temperature T1 can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the dissolution reaction time t1 can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. For example, the solid content W1 of the slurry can be 2g / L, 3g / L, 4g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 34g / L, 40g / L, 45g / L, or 50g / L, or any two of the above numbers. For example, the pH of the slurry can be 3, 3.5, 4, 4.5, 5, 5.5, or 6, or any two of the above numbers.

[0158] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least positive electrode powder and reducing agent are added to maintain the solid content W2 of the slurry within the range of 2 g / L to 50 g / L and the pH of the slurry within the range of 3 to 6. The electrolytic treatment temperature T2 is 20℃ to 95℃ and the voltage is 2.5V to 4.5V. For example, the solid content W2 of the slurry during the electrolytic treatment can be maintained at 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry during the electrolytic treatment can be maintained at 3, 3.5, 4, 4.5, 5, 5.5 or 6, or between any two of the above numbers. For example, the electrolytic treatment temperature T2 can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 95℃, or any two of the above numbers. For example, the electrolytic treatment voltage can be 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, 4V, 4.1V, 4.2V, 4.3V, 4.4V, or 4.5V, or any two of the above numbers.

[0159] In some embodiments of this application, the current density of the electrolysis process is 5 A / m. 2 Up to 500A / m 2 .

[0160] In some embodiments of this application, the electrolysis process is performed while the slurry is stirred at a speed of 50 rpm to 1000 rpm. For example, the stirring speed can be 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, or 1000 rpm, or any two of the above numbers. This allows the dissolution and electrolysis reactions to fully occur, thereby improving the recovery efficiency.

[0161] The recycling method of this application includes the above steps (2) and (3). During the recycling process, electrolysis can generate sulfuric acid. This self-sustaining process can reduce the use of sulfuric acid in the recycling process and reduce the recycling cost. In addition, the dissolution reaction and the electrolysis reaction work together. The added positive electrode powder consumes sulfuric acid through the dissolution reaction, so that the electrolysis reaction continues to proceed within a suitable pH range. The electrolysis reaction will generate sulfuric acid, which maintains the recycling of sulfuric acid. At the same time, it can continuously dissolve the newly added positive electrode powder so that the dissolution reaction continues, reducing the use of sulfuric acid and avoiding the introduction of excess alkaline impurities, further reducing the recycling cost, and continuously recovering elements in the positive electrode material.

[0162] In some embodiments of this application, when the mass of nickel and / or cobalt added to the cathode product is m1, cathode powder and reducing agent are added; wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0 or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, cathode powder and reducing agent are added while the electrolysis reaction is being carried out, which is beneficial to achieving continuous recovery. For example, m1 = 0.1m0, that is, when the cathode produces a certain amount of product, positive electrode powder and reducing agent are added.

[0163] In some embodiments of this application, the amount of added cathode powder is determined based on the amount of nickel and / or cobalt produced by electrolysis, and the total amount of nickel and / or cobalt contained in the added cathode powder is as similar as possible to the amount of nickel and cobalt metal produced. Specifically, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt in the added cathode powder is N2, where 0.95N1≤N2≤1.05N1. For example, N2 can be 0.95N1, 0.96N1, 0.97N1, 0.98N1, 0.99N1, N1, 1.01N1, 1.02N1, 1.03N1, 1.04N1, or 1.05N1, or any two of the above values. The amount of reducing agent added is determined based on the total amount of metals (e.g., at least one of nickel, cobalt, and manganese) to be reduced in the added cathode powder. Specifically, the total molar amount of the second metal element in the added positive electrode powder is N3, and the molar amount of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3. For example, N4 can be 0.25N3, 0.5N3, 0.75N3, 1N3, 1.25N3, 1.5N3, 1.75N3, 2N3, 2.25N3, 2.5N3, 2.75N3, or 3N3, or any two of the above numbers. By adjusting N3 and N4 to meet the above ranges, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so as to ensure the continuous operation of the electrolysis process.

[0164] In some embodiments of this application, when the mass of nickel and / or cobalt added to the cathode product is m1, positive electrode powder, reducing agent, and sulfuric acid are added; wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0, or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, the positive electrode powder, reducing agent and sulfuric acid are added while the electrolysis reaction is taking place, which is beneficial to achieving continuous recovery. As another example, m1 = 0.1m0, that is, when a certain amount of product is produced at the cathode, the positive electrode powder, reducing agent and sulfuric acid are added.

[0165] In this method, the amount of added positive electrode powder and reducing agent is the same as described above, and will not be repeated here. The amount of added sulfuric acid is described below.

[0166] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7. The number of moles of added sulfuric acid is expressed as the number of moles of "H2SO4".

[0167] Surprisingly, with this process, the amount of sulfuric acid added only needs to meet the requirements of the first metallic element, without the need for large amounts of sulfuric acid.

[0168] Specifically, when the reducing agent does not contain sulfur (S), i.e., the reducing agent is selected from hydrogen peroxide, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and the reducing agent. This satisfies 0.9×(0.5N5+0.5N7)≤N6≤1.1×(0.5N5+0.5N7). For example, N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, and N7 to satisfy the above relationship, the solid content W2 of the slurry is maintained within the range of 1 g / L to 50 g / L and the pH is maintained within the range of 2 to 6.5 during the electrolysis process, so as to ensure that the electrolysis process can continue.

[0169] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, and sodium metabisulfite, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and the reducing agent, as well as the amount of sulfur in the reducing agent. The number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7). For example, N8+N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, N7, and N8 to satisfy the above relationship, the solid content W2 of the slurry is maintained within the range of 1 g / L to 50 g / L and the pH is maintained within the range of 2 to 6.5 during the electrolysis process, so as to ensure that the electrolysis process can continue.

[0170] In some embodiments of this application, in step (3), the anode and cathode in the electrolysis process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0171] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T3 of the high-temperature treatment can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C, or any two of the above numbers. For example, the time t3 of the high-temperature treatment can be 0.1h, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h, or any two of the above numbers. The positive current collector and positive electrode material layer of the disassembled positive electrode are separated. The positive electrode material layer is then crushed and sieved to prepare positive electrode material layer powder within a certain particle size range. Subsequently, the positive electrode material layer powder is subjected to high-temperature treatment to remove the conductive agent and binder, thereby obtaining the positive electrode powder. This application does not impose any particular limitation on the particle size of the positive electrode material layer powder, as long as it achieves the purpose of this application. For example, the volume average particle size of the positive electrode material layer powder can be from 10 μm to 300 μm.

[0172] In some embodiments of this application, the electrolyzed slurry is filtered to obtain filter residue (unreacted cathode powder) and a filtrate containing a first metal element. The filtrate is then purified to obtain a salt containing the first metal element. In this application, the electrolyzed slurry can be the slurry discharged during the electrolysis process (i.e., the slurry during electrolysis) or the slurry obtained after the electrolysis process (i.e., the slurry after electrolysis). The salt containing the first metal element obtained by purifying the filtrate can be a lithium salt or a sodium salt, thereby achieving the recovery of the first metal element.

[0173] In some embodiments of this application, the filter residue obtained from filtration is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely reacted / recovered during the electrolytic reaction, and the filter residue may still contain the target metal, i.e., the first metal element and / or the second metal element. Adding the filter residue to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process. Furthermore, during electrolytic treatment, as the electrolytic reaction proceeds, the ion concentration of the first metal element in the liquid phase of the slurry increases, allowing electrolysis to be stopped, or a portion of the electrolyzed slurry can be discharged. If the slurry is discharged, the Ni and / or Co element content in the system will decrease. Therefore, the mother liquor obtained after lithium / sodium extraction from the discharged slurry is added to the slurry for further electrolytic treatment. Since the mother liquor has a high Ni and / or Co element content, adding it to the slurry helps to dynamically maintain the Ni and / or Co element ion concentration in the liquid phase of the slurry within a relatively constant range, thus facilitating the continuous progress of the electrolytic reaction.

[0174] In some embodiments of this application, the first metal element is selected from sodium or lithium. The purification process is concentrated crystallization. The filtrate is concentrated and crystallized to obtain concentrated mother liquor and salt containing the first metal element, that is, sodium salt or lithium salt, thereby realizing the recovery of the first metal element.

[0175] The concentrated mother liquor is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely recovered during the concentration and crystallization process, and the concentrated mother liquor may still contain the target metal, primarily Ni and / or Co. Adding the concentrated mother liquor to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process. Furthermore, for continuous electrolysis schemes, the Ni and / or Co elements in the concentrated mother liquor can help maintain the Ni and / or Co ion concentration in the slurry liquid phase within a relatively constant range; therefore, it must be returned to the slurry to ensure the electrolytic reaction can continue uninterrupted.

[0176] In some embodiments of this application, the first metallic element is selected from lithium. The purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. After carbonization deposition, the filtrate yields a lithium-containing salt, a mother liquor, and optionally a salt containing nickel and / or cobalt, thereby achieving lithium recovery. In some embodiments of this application, the mother liquor and optionally the nickel- and / or cobalt-containing salt are returned to the slurry for further electrolysis to improve the recovery rate of Ni and / or Co.

[0177] For schemes where electrolysis is stopped after a period of time, the filtrate is carbonized and deposited to obtain lithium-containing salts and a mother liquor. The mother liquor is collected and added to the slurry for electrolysis in the next electrolysis process. This not only improves the final recovery rate of the target metal but also reduces liquid waste during the recovery process.

[0178] In continuous electrolysis schemes, when lithium is extracted using carbonization deposition, elements such as nickel and cobalt will also be deposited in solid form (e.g., nickel carbonate, cobalt carbonate), resulting in salts containing nickel and / or cobalt. In this case, the nickel / cobalt carbonate can be returned to the slurry to improve the recovery rate of nickel and cobalt. Furthermore, returning it to the slurry helps to dynamically maintain the concentration of Ni and / or Co ions in the liquid phase of the slurry within a relatively constant range.

[0179] This process uses slurry electrolysis and concentration crystallization or carbonization deposition to separate and extract valuable metals from the cathode materials of spent batteries. The acid generated during slurry electrolysis to separate nickel and cobalt continuously dissolves the cathode powder in the solid phase of the slurry, enriching lithium while separating nickel and cobalt, significantly reducing acid consumption. The resulting lithium-rich filtrate can be purified to obtain high-purity lithium sulfate or lithium carbonate. By adding cathode powder, reducing agent, and optionally sulfuric acid during electrolysis, slurry electrolysis can be carried out continuously, resulting in a high recovery rate of valuable metals. Of course, even for electrolysis termination schemes, the electrolysis process needs to continue for a period of time until the sulfuric acid is depleted or the Li in the slurry is reduced. + Stop when the concentration reaches saturation and electrolysis can no longer proceed.

[0180] The following are some possible implementation methods:

[0181] Method 1: The first metal element is selected from lithium, the reducing agent is selected from sulfur dioxide, the feed is positive electrode powder and sulfur dioxide, the electrolysis is stopped after a period of time, and the slurry after the electrolysis is completed is purified to obtain Li element. The purification treatment can be concentration crystallization or carbonization deposition.

[0182] Method 2: The first metal element is selected from lithium, the reducing agent is selected from sulfur dioxide, the feed is positive electrode powder and sulfur dioxide, part of the electrolytic slurry is discharged to keep the electrolysis running continuously, the discharged electrolytic slurry is purified to obtain Li element, the mother liquor after lithium extraction needs to be returned to the slurry, the lithium extraction process can be concentration crystallization or carbonization deposition, when returning the mother liquor after carbonization deposition it is best to remove the sodium.

[0183] Method 3: The first metal element is selected from lithium, the reducing agent is selected from hydrogen peroxide, the feed is positive electrode powder and hydrogen peroxide, the electrolysis is stopped after a period of time, and the slurry after the electrolysis is completed is purified to obtain Li element. The purification process can be concentrated and crystallized or carbonized and deposited.

[0184] Method 4: The first metal element is selected from lithium, the reducing agent is selected from hydrogen peroxide, and the feed consists of positive electrode powder, hydrogen peroxide and sulfuric acid. Part of the slurry in the electrolysis is discharged to keep the electrolysis running. The discharged slurry in the electrolysis is purified to obtain Li element. The mother liquor after lithium extraction needs to be returned to the slurry. The lithium extraction process can be concentration and crystallization or carbonization deposition. When returning the mother liquor by carbonization deposition, it is best to remove the sodium.

[0185] Method 5: The first metal element is selected from lithium, and the reducing agent is selected from any one of sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The feed is positive electrode powder and the above-mentioned reducing agent. Electrolysis is stopped after a period of time. The slurry after electrolysis is purified to obtain Li element. The lithium extraction process is carbonization deposition.

[0186] Method 6: The first metal element is selected from lithium, and the reducing agent is selected from any one of sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The feed consists of positive electrode powder, the above-mentioned reducing agent, and sulfuric acid. Part of the electrolytic slurry is discharged to keep the electrolysis running continuously. The discharged electrolytic slurry is purified to obtain Li element. The mother liquor after lithium extraction needs to be returned to the slurry. The lithium extraction process is carbonization deposition. When returning the mother liquor, it is best to remove the sodium.

[0187] Of course, for sodium batteries, those skilled in the art can choose similar lithium battery solutions based on the teachings of this application, which will not be elaborated here.

[0188] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0189] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0190] In some embodiments of this application, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as the reducing agent, undergoes the following dissolution reactions:

[0191] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2;

[0192] Electrolysis reactions include:

[0193] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0194] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0195] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0196] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4;

[0197] The elemental nickel and cobalt generated during electrolysis can act as catalysts, partially decomposing hydrogen peroxide into water and oxygen, specifically: 2H₂O₂=2H₂O+O₂; thus, the overall reaction is:

[0198] 10LiNi 0.5 Co0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0199] As can be seen from the above reaction formula, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as a reducing agent, during the dissolution reaction, although Co, Ni, and Mn consume SO4... 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Li consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0200] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0201] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0202] In some embodiments of this application, the positive electrode powder comprises NaNiO2, with sodium metabisulfite (Na2S2O5) as a reducing agent, and its dissolution reaction includes:

[0203] 4NaNiO2+Na2S2O5+5H2SO4=3Na2SO4+5H2O+4NiSO4;

[0204] Electrolysis reactions include:

[0205] 2NiSO4+2H2O=2Ni+2H2SO4+O2;

[0206] The overall reaction is:

[0207] 4NaNiO2+Na2S2O5+H2SO4=4Ni+H2O+2O2+3Na2SO4.

[0208] As can be seen from the above reaction formula, the positive electrode powder includes NaNiO2, and sodium metabisulfite is used as a reducing agent. During the dissolution reaction, Ni consumes SO4. 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Na consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0209] In this process, the continuously added positive electrode powder and sulfuric acid work together through a dissolution reaction and an electrolysis reaction that occurs in the same or connected containers. Specifically, the added positive electrode powder consumes sulfuric acid through a dissolution reaction, allowing the electrolysis reaction to continue within a suitable pH range. The electrolysis reaction also produces sulfuric acid, maintaining the recycling of sulfuric acid while continuously dissolving the newly added positive electrode powder, thus increasing the amount of positive electrode powder processed, reducing the use of sulfuric acid, avoiding the introduction of excess alkaline impurities, and enabling the sustainable recycling of positive electrode materials from waste batteries.

[0210] The recycling method provided in this application uses dissolution, electrolysis, and concentrated crystallization / carbonization deposition to separate, extract, and recover valuable metals, namely the first and second metallic elements, from waste battery cathode powder. Electrolysis separates metals such as nickel and cobalt contained in the initial acidic slurry. Because the sulfuric acid produced by the electrolysis reaction can be used to further dissolve more cathode powder in the slurry, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and efficient. In addition, the recycling method provided in this application can perform continuous electrolysis (including electrolysis with a pause after a period of time and continuous electrolysis without interruption), because the sulfuric acid produced by electrolysis or the added sulfuric acid can dissolve more cathode powder, thereby improving the recovery rate and production capacity. Therefore, the entire recycling process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method.

[0211] Traditional recycling processes mainly include pyrometallurgy and hydrometallurgy. Pyrometallurgy extracts valuable metals or compounds from cathode materials through high-temperature treatment. While the process is simple, it suffers from low recovery efficiency and product quality, and easily generates harmful gases that pollute the environment. Hydrometallurgy involves pre-treating the cathode material and then using processes such as acid leaching and extraction to enrich the valuable metals for recovery or utilization. These methods typically use large amounts of acids, alkalis, and extraction solutions, increasing recycling costs and resulting in low recycling efficiency, making large-scale industrialization impossible.

[0212] This application also provides a method for recycling the positive electrode of waste batteries, which reduces the amount of sulfuric acid solution used in the recycling process and achieves continuous, uninterrupted recycling, greatly improving recycling efficiency and possessing significant industrialization value. In this process, different continuous electrolysis schemes are designed for different systems. The specific technical solutions are as follows:

[0213] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0214] (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0215] (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone a dissolution reaction. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate and sodium metabisulfite.

[0216] (3) Electrolyze the slurry. During the electrolysis process, at least the positive electrode powder and the reducing agent are added to the slurry. When the preset conditions are met, a portion of the electrolyzed slurry is discharged. The discharged electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element. The electrolyzed slurry is an electrolysis slurry.

[0217] The preset condition is 0.7C2≤C1<C2, wherein the concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C1, and the theoretical saturation concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C2.

[0218] (4) The filtrate containing the first metal element is purified to obtain salt and mother liquor containing the first metal element. The mother liquor is returned to the slurry in step (3) for further electrolysis.

[0219] In some embodiments of this application, when the preset conditions are met, the volume of the electrolyzed slurry discharged is V1, and the volume of the mother liquor returned in step (3) is V2, where 0.95V1≤V2<V1.

[0220] In some embodiments of this application, the volume of the slurry in step (2) is V3, where V1 ≤ 0.2V3.

[0221] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0222] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0223] In some embodiments of this application, step (3) involves adding at least the positive electrode powder and the reducing agent to the slurry, including: adding the positive electrode powder and the reducing agent to the slurry; or, adding the positive electrode powder, the reducing agent, and sulfuric acid to the slurry.

[0224] In some embodiments of this application, the positive electrode powder and the reducing agent are added, or the positive electrode powder, the reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.5.

[0225] In some embodiments of this application, the recycling method includes the following steps: steps (2) and (3) include:

[0226] (2) The slurry is obtained by mixing at least the positive electrode powder, sulfuric acid, the reducing agent, and water and then dissolving them. The slurry contains the solid phase and the liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The dissolution temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the mixed slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite.

[0227] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

[0228] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt added to the cathode product during the electrolysis process is m1, the positive electrode powder and the reducing agent are added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2).

[0229] In some embodiments of this application, the total number of moles of nickel and / or cobalt added to the cathode product is N1, the total number of moles of nickel and / or cobalt added to the cathode powder is N2, and 0.95N1≤N2≤1.05N1; the total number of moles of the second metal element added to the cathode powder is N3, and the total number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0230] In some embodiments of this application, the reducing agent is sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

[0231] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, the reducing agent, and sulfuric acid are added during the electrolysis process.

[0232] In some embodiments of this application, sulfuric acid is added when the mass of nickel and / or cobalt in the cathode product increases by m1 during the electrolysis process; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0233] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7; wherein, when the reducing agent does not contain sulfur, the following condition is met: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7); or, when the reducing agent contains sulfur, the total number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7); wherein, the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0234] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0235] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0236] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; wherein, when the reducing agent does not contain sulfur, it satisfies 0.9╳(0.5P1+P2+0.5P4)≤P3≤1.1╳(0.5P1+P2+0.5P4); or, when the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9╳(0.5P1+P2+0.5P4)≤P3+P5≤1.1╳(0.5P1+P2+0.5P4); wherein, the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0237] In some embodiments of this application, the first metal element is selected as sodium or lithium, the purification process is concentration and crystallization, the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element; the concentrated mother liquor is returned to the slurry in step (3) for further electrolytic treatment.

[0238] In some embodiments of this application, lithium is selected as the first metal element, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate, after carbonization deposition, yields a lithium-containing salt, a nickel- and / or cobalt-containing salt, and a deposition mother liquor. The nickel- and / or cobalt-containing salt and the deposition mother liquor are then returned to the slurry in step (3) for further electrolytic treatment. In some embodiments of this application, the deposition mother liquor is subjected to sodium removal treatment and then returned to the slurry in step (3) for further electrolytic treatment.

[0239] In actual production, because electrolysis does not stop, the entire process can last for a very long time, so the total volume of the system will change. In order to keep the system stable, the following methods can be adopted: In some embodiments of this application, the mother liquor is evaporated and concentrated and then added to the slurry in step (3) to continue the electrolysis treatment, and / or, during the electrolysis treatment, water is added to the slurry in the electrolysis to keep the volume of the system relatively unchanged and maintain the stability of the system.

[0240] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0241] In some embodiments of this application, in step (3), the anode and cathode in the electrolytic process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0242] In some embodiments of this application, the electrolysis process continues without interruption.

[0243] The recycling method provided in this application is used to recover valuable metals, namely the first and second metallic elements, from the positive electrode powder of spent batteries. Metals such as nickel and cobalt contained in the initial acidic slurry are separated by electrolysis. Because the sulfuric acid produced by the electrolysis reaction can be used to further dissolve more positive electrode powder in the slurry, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and effective. Simultaneously, the recycling method provided in this application can perform continuous electrolysis without interruption. Because the electrolysis produces sulfuric acid or adds sulfuric acid to dissolve more positive electrode powder, the electrolysis and dissolution reactions continue. Periodically discharging part of the slurry and timely replenishing the mother liquor maintains system stability, thereby achieving continuous recycling and improving recovery rate and capacity. Therefore, the entire recycling process is simple, economical, and efficient, enabling large-scale industrialization. By reducing the use of acid and alkali, it reduces environmental impact, making it an environmentally friendly recycling method.

[0244] In this process, the dissolution and electrolysis of the cathode powder take place in the same electrolytic cell / container or connected containers. This allows the H2SO4 generated during electrolysis to continuously dissolve newly added cathode powder, ensuring full utilization of sulfuric acid and reducing acid consumption. The amount of sulfuric acid used in this process is significantly reduced compared to traditional processes. Specifically, in traditional recovery processes, when sulfuric acid is used, elements such as Li, Na, Co, Ni, and Mn in the cathode powder all need to react with SO4. 2-The recovery of elements requires a combination of factors. If we consider sulfur (S), 2 mol of Li corresponds to 1 mol of S, 2 mol of Na corresponds to 1 mol of S, and 1 mol of Co / Ni / Mn corresponds to 1 mol of S. This means the molar amount of S needs to match the total molar amount of Li, Na, Co, Ni, and Mn. Therefore, the recovery process requires a large amount of sulfuric acid, increasing costs. In this process, only the molar amount of S corresponding to the molar amount of Li is needed, reducing the overall demand for S, or in other words, reducing the demand for sulfuric acid or acidic substances, thus lowering recovery costs. Furthermore, the sulfuric acid produced during electrolysis, or the added sulfuric acid, dissolves more of the cathode powder, allowing the dissolution reaction to continue. During electrolysis, a portion of the slurry is discharged, and the mother liquor is returned to the slurry for further electrolysis. This keeps the ion concentration of Ni and / or Co in the slurry liquid phase dynamically within a relatively constant range, maintaining the continuous electrolysis reaction. Thus, the electrolysis and dissolution reactions can proceed simultaneously and continuously during the recovery process, achieving continuous recovery.

[0245] In this process, the following aspects need to be considered to achieve continuous electrolysis without interruption: 1) Feeding is required during electrolysis: For the SO2 system, only reducing agent and cathode powder need to be added, as the overall reaction does not consume sulfuric acid; for hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite systems, in addition to reducing agent and cathode powder, sulfuric acid must also be added, as the overall reaction consumes sulfuric acid; 2) A portion of the slurry needs to be discharged during electrolysis, because as electrolysis proceeds, the amount of Li2SO4 in the slurry increases to the point of saturation and precipitation, making continuous electrolysis impossible. Therefore, a portion of the slurry needs to be discharged to ensure that the Li2SO4 content in the system remains stable. + Or Na + Concentration balance; 3) It is necessary to maintain Ni concentration in the system. 2+ / Co 2+ The dynamic balance of Ni content means that discharging part of the slurry will inevitably lead to an increase in Ni content in the system. 2+ / Co 2+ The decrease in Ni content necessitates maintaining a certain level of Ni for continued electrolysis. 2+ / Co 2+ The dynamic balance of content means that the mother liquor obtained after lithium or sodium extraction from the discharged slurry is returned to the system.

[0246] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0247] (1) Disassemble waste batteries to obtain positive electrode, pre-treat the positive electrode to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt and manganese;

[0248] (2) At least positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate and sodium metabisulfite.

[0249] (3) Electrolyze the slurry. During the electrolysis process, at least positive electrode powder and reducing agent are added to the slurry. When the preset conditions are met, a portion of the electrolyzed slurry is discharged. The discharged electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element. The electrolyzed slurry is the slurry in the electrolysis process.

[0250] The preset condition is 0.7C2≤C1<C2, where the concentration of the salt corresponding to the first metal element in the electrolytically treated slurry is C1, and the theoretical saturation concentration of the salt corresponding to the first metal element in the electrolytically treated slurry is C2.

[0251] (4) The filtrate containing the first metal element is purified to obtain the salt containing the first metal element and the mother liquor. The mother liquor is returned to the slurry in step (3) for further electrolytic treatment.

[0252] The recycling method provided in this application involves carrying out the dissolution reaction and electrolysis process in the same or connected containers. On one hand, by adding at least positive electrode powder and a reducing agent, the sulfuric acid generated during the electrolysis process can continuously dissolve the solid phase of the positive electrode powder in the slurry, allowing the dissolution reaction and electrolysis to proceed simultaneously, and reducing the amount of sulfuric acid required for replenishment during the reaction. On the other hand, the generation of sulfuric acid during the electrolysis process reduces the actual consumption of SO4. 2- SO4 consumed only by the first metallic element in the cathode powder 2- That is, the overall reaction only needs to provide Li + Required SO4 2- That is, compared to traditional recycling processes that simultaneously consume both the first and second metal elements (SO4), 2- Technical solution: The SO4 recycling method of this application 2-The consumption of sulfuric acid is greatly reduced, thus reducing the demand for sulfuric acid. Furthermore, the sulfuric acid produced by electrolysis, or the added sulfuric acid, dissolves more cathode powder, allowing the dissolution reaction to continue. Simultaneously, as the electrolysis proceeds, the concentration of the first metal element ions in the liquid phase of the slurry increases, requiring the discharge of some of the slurry. However, after discharge, the content of the second metal element (e.g., Ni and / or Co) in the system decreases. Therefore, the mother liquor obtained after filtering and purifying the discharged slurry is added back to the slurry for continued electrolysis. The Ni and / or Co content in the mother liquor is highly compatible with the required Ni and / or Co content in the system. Adding it to the slurry keeps the Ni and / or Co ion concentration in the liquid phase of the slurry dynamically within a relatively constant range, allowing the electrolysis reaction to continue uninterrupted. Thus, the electrolysis and dissolution reactions can proceed simultaneously and continuously during the recovery process, achieving uninterrupted continuous recovery and improving recovery rate and production capacity. In addition, if the concentration of the first metal element ions in the electrolyzed slurry is too low, it indicates that the reaction is incomplete. If the concentration of the first metal element ions is too high, it will affect the progress of the electrolysis reaction. Therefore, when the preset conditions meet 0.7C2≤C1<C2, a portion of the electrolyzed slurry can be discharged, which is economically efficient. Specifically, C1 can be 0.7C2, 0.71C2, 0.72C2, 0.73C2, 0.74C2, 0.75C2, 0.76C2, 0.77C2, 0.78C2, 0.79C2, 0.8C2, 0.81C2, 0.82C2, 0.83C2, 0.84C2, 0.85C2, 0.86C2, 0.87C2, 0.88C2, 0.89C2, 0.9C2, 0.91C2, 0.92C2, 0.93C2, or 0.94C2, 0.95C2, 0.96C2, 0.97C2, 0.98C2, or 0.99C2, or any two of the above numbers. Furthermore, no harmful gases are generated during the entire recycling process, making it an environmentally friendly recycling method.

[0253] In some embodiments of this application, when the first metal element is lithium, C2 is 335 g / L to 345 g / L, for example, C2 can be set to 340 g / L.

[0254] When the first metallic element is sodium, C2 is 395 g / L to 405 g / L. For example, C2 can be set to 400 g / L.

[0255] A sustainable electrolysis scheme involves continuous electrolysis without interruption. When the lithium-ion concentration or sodium-ion concentration (or its corresponding salt) reaches a preset condition, a portion of the slurry is discharged from the electrolysis process to maintain the lithium-ion or sodium-ion concentration within a certain range.

[0256] In some embodiments of this application, when preset conditions are met, the volume of the slurry discharged from the electrolysis process is V1, and the volume of the mother liquor returned to step (3) is V2, where 0.95V1 ≤ V2 < V1. In some embodiments of this application, the volume of the slurry in step (2) is V3, where V1 ≤ 0.2V3. For example, V2 can be 0.95V1, 0.96V1, 0.97V1, 0.98V1, or 0.99V1, or any two of the above numbers. For example, V1 can be 0.01V3, 0.02V3, 0.03V3, 0.04V3, 0.05V3, 0.06V3, 0.07V3, 0.08V3, 0.09V3, 0.1V3, 0.11V3, 0.12V3, 0.13V3, 0.14V3, 0.15V3, 0.16V3, 0.17V3, 0.18V3, 0.19V3, or 0.2V3, or any two of the above values. By adjusting V1, V2, and V3 to satisfy the above relationship, the electrolysis reaction and the dissolution reaction can proceed simultaneously and continuously, achieving continuous recovery, improving recovery rate and production capacity, and resulting in high economic benefits.

[0257] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5. For example, the solid content W1 of the slurry can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or 6.5, or between any two of the above numbers.

[0258] By adjusting the pH of the slurry in step (2) within the above-mentioned range, the electrolysis process can proceed stably, because excessively high or low pH values ​​during electrolysis will affect the normal operation of the electrolysis process. For example, if the pH value is too low, H2 gas is easily generated during electrolysis, which will affect the electrolysis production of elemental metals; if the pH value is too high, there is a risk that the metal elements will form alkaline precipitates, which will also affect the normal operation of the electrolysis process.

[0259] By controlling the solid content W1 of the slurry in step (2) within the above range, the H+ content can be prevented from increasing due to the continuous generation of sulfuric acid during subsequent electrolytic treatment. + The accumulation of these deposits can then affect subsequent electrolytic processing.

[0260] Specifically, because the pH value needs to be within the range of 2 to 6.5 during electrolysis, and the electrolysis reaction often occurs rapidly, a large amount of H2SO4 (H+) can be produced in a short period of time.+ The dissolution reaction is relatively slow. In this process, electrolysis is continued uninterrupted by subsequent feeding, and the slurry must always have a certain solid content. If the cathode powder is completely dissolved throughout the process, the difference in reaction rates between the two will result in a higher H2 content during electrolysis. + Unable to react with the positive electrode powder in time, resulting in H + Excessive accumulation causes the pH of the electrolytic slurry to drop, making it unsuitable for electrolysis (at which point the electrolysis product is H2 instead of metal), and electrolysis cannot continue. Conversely, when the slurry contains some undissolved cathode powder, although the dissolution reaction rate is still slow, the increased amount of reactants results in a higher H2 consumption per unit time. + Increasing the pH level can keep the slurry pH within the required range, allowing electrolysis to continue.

[0261] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h. For example, the temperature T1 of the dissolution reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the time t1 of the dissolution reaction can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. By controlling the temperature T1 and time t1 of the dissolution reaction within the above range, it is beneficial to fully dissolve the cathode powder to obtain the slurry with the desired solid content.

[0262] In some embodiments of this application, in step (2), the sulfuric acid is commercially available concentrated sulfuric acid.

[0263] In some embodiments of this application, the cathode material includes LiMO2 or NaMO2, where M is selected from at least one of Ni, Co, and Mn. When the cathode material includes LiMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of Li2SO4, NiSO4, CoSO4, MnSO4, H2O, and H2SO4. When the cathode material includes NaMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of NiSO4, CoSO4, MnSO4, H2O, H2SO4, and Na2SO4.

[0264] In some embodiments of this application, the first metal element is lithium, and the preferred reducing agent is selected from hydrogen peroxide and / or sulfur dioxide, which can simplify subsequent steps.

[0265] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0266] Specifically, when the reducing agent does not contain sulfur (S), that is, the reducing agent is selected from hydrogen peroxide. The condition 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4) must be met. For example, P3 can be 0.9 × (0.5P1 + P2 + 0.5P4), 0.92 × (0.5P1 + P2 + 0.5P4), 0.94 × (0.5P1 + P2 + 0.5P4), 0.95 × (0.5P1 + P2 + 0.5P4), 0.96 × (0.5P1 + P2 + 0.5P4), 0.98 × (0.5P1 + P2 + 0.5P4), 1 × The formulas are (0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above values. By adjusting the relationship between P1, P2, P3, and P4 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0267] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, the molar number of S in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4). For example, P3+P5 can be 0.9×(0.5P1+P2+0.5P4), 0.92×(0.5P1+P2+0.5P4), 0.94×(0.5P1+P2+0.5P4), 0.95×(0.5P1+P2+0.5P4), 0.96×(0.5P1+P2+0.5P4), 0.98×(0.5P1+P2+0.5P4), 1 ×(0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above numbers. By adjusting the relationship between P1, P2, P3, P4, and P5 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0268] In this scheme, sulfuric acid is used to dissolve most of the positive electrode powder. The amount of sulfuric acid added is only enough to dissolve the preset amount of positive electrode powder that needs to be dissolved. A small portion of the positive electrode powder must remain undissolved (i.e., to ensure that a certain solid content is maintained in the slurry). This ensures that the dissolution reaction can be fully carried out during subsequent continuous feeding and electrolysis, avoids a decrease in the pH of the system, and keeps the pH within a suitable range during the electrolysis process, allowing the electrolysis process to continue.

[0269] In some embodiments of this application, in step (3), at least positive electrode powder and reducing agent are added to the slurry, including method one, adding positive electrode powder and reducing agent to the slurry. In this method, the reducing agent is sulfur dioxide, that is, only positive electrode powder and reducing agent are added during the electrolytic treatment. On the one hand, a) when SO2 is used as a reducing agent, it can also act as a source of "S", which is converted into SO4 during the electrolytic treatment. 2- This design ensures that the overall system does not consume sulfuric acid. Therefore, during electrolysis, only cathode powder and reducing agent need to be added, without the need for sulfuric acid replenishment. This allows for continuous slurry electrolysis, meaning electrolysis can continue without interruption, only requiring periodic discharge of a portion of the electrolyzed slurry. Consequently, the demand for sulfuric acid is further reduced throughout the recycling process, leading to lower recycling costs. Furthermore, the added cathode powder acts as an "alkali," reacting with the H+ ions in the sulfuric acid produced during electrolysis. +The reaction proceeds while maintaining the pH value within the range necessary for normal electrolysis. A pH value that is too high or too low will affect the normal operation of the electrolysis process. Therefore, in this process, the added positive electrode powder and reducing agent continuously undergo dissolution and electrolysis reactions with the sulfuric acid produced during electrolysis. This not only consumes the H₂ produced during electrolysis but also... + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable. More importantly, by coordinating regular discharge and return of mother liquor, electrolysis can be carried out continuously without interruption. Therefore, by continuously adding positive electrode powder and reducing agent to react with the sulfuric acid produced during electrolysis, the pH of the slurry can be adjusted without the need for adding alkali to adjust the pH during the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities. Electrolysis can be carried out continuously without interruption, thus facilitating continuous recovery.

[0270] In some embodiments of this application, in step (3), at least positive electrode powder and reducing agent are added to the slurry, including method two, adding positive electrode powder, reducing agent and sulfuric acid to the slurry. The reducing agent in this method is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, reducing agent and sulfuric acid are added during the electrolysis process. When hydrogen peroxide, sodium sulfite, sodium thiosulfate, or sodium metabisulfite are used as reducing agents, the total reaction only requires the consumption of the first metallic element, such as Li. + The corresponding SO4 2- To ensure the electrolysis process can continue uninterrupted, sulfuric acid, along with necessary positive electrode powder and reducing agent, needs to be replenished. However, since sulfuric acid is also generated during electrolysis, only a portion of the sulfuric acid is consumed. Therefore, compared to existing technologies where both the first and second metal elements are consumed simultaneously (SO4), the recovery process consumes less sulfuric acid during the entire process. 2- The technical solution reduces the amount of sulfuric acid required (especially for reducing agents such as sodium sulfite, sodium thiosulfate, and sodium metabisulfite, where the sulfuric acid requirement is further reduced), thus lowering recycling costs. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ ions in the sulfuric acid produced during electrolysis. + The reaction proceeds to ensure the pH value remains within the range necessary for normal electrolysis. A pH value that is too high or too low will negatively impact the electrolysis process. Therefore, this process utilizes the added positive electrode powder, reducing agent, and sulfuric acid to continuously undergo dissolution and electrolysis reactions with the sulfuric acid produced during electrolysis. This not only consumes the H₂ produced during electrolysis but also...+ This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable; more importantly, by adding sulfuric acid, combined with regular discharge and return of mother liquor, electrolysis can be carried out continuously without interruption. Therefore, by continuously adding positive electrode powder, reducing agent, and sulfuric acid, the pH of the slurry electrolysis can be adjusted without the need for adding alkali to adjust the pH of the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities. Electrolysis can be carried out continuously without interruption, thus facilitating continuous recovery.

[0271] In some embodiments of this application, positive electrode powder and reducing agent are added, or positive electrode powder, reducing agent and sulfuric acid are added, to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5. For example, the solid content W2 of the slurry can be maintained at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be maintained at 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 or 6.5, or between any two of the above numbers. During the electrolytic treatment process, the pH value of the slurry is maintained within the range of 2 to 6.5. The electrolytic reaction rate is relatively fast, and a large amount of H2SO4, i.e., H+, can be generated in a short period of time. + An increase in pH will decrease the pH value, and if the pH is too low, it will affect the electrolysis reaction rate. Generally, the dissolution reaction rate is slower than the electrolysis reaction rate. Therefore, to maintain the slurry solid content W2 within the range of 1 g / L to 50 g / L, the amount of H₂ consumed per unit time... + Increasing the concentration of the positive electrode powder, reducing agent, and optional sulfuric acid can maintain the slurry pH within the range of 2 to 6.5. This allows the dissolution and electrolysis reactions to continue, and also prevents the H+ from being reduced due to the continuous generation of sulfuric acid. + This accumulation can hinder the normal operation of the electrolytic process.

[0272] In some embodiments of this application, the recycling method includes the following steps: Steps (2) and (3) include:

[0273] (2) A slurry is obtained by mixing at least positive electrode powder, sulfuric acid, a reducing agent, and water and then reacting the mixture to obtain a slurry containing a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The dissolution temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the mixed slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite. For example, the dissolution reaction temperature T1 can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the dissolution reaction time t1 can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. For example, the solid content W1 of the slurry can be 2g / L, 3g / L, 4g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 34g / L, 40g / L, 45g / L, or 50g / L, or any two of the above numbers. For example, the pH of the slurry can be 3, 3.5, 4, 4.5, 5, 5.5, or 6, or any two of the above numbers.

[0274] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least positive electrode powder and reducing agent are added to maintain the solid content W2 of the slurry within the range of 2 g / L to 50 g / L and the pH of the slurry within the range of 3 to 6. The electrolytic treatment temperature T2 is 20℃ to 95℃ and the voltage is 2.5V to 4.5V. For example, the solid content W2 of the slurry during the electrolytic treatment can be maintained at 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry during the electrolytic treatment can be maintained at 3, 3.5, 4, 4.5, 5, 5.5 or 6, or between any two of the above numbers. For example, the electrolytic treatment temperature T2 can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 95℃, or any two of the above numbers. For example, the electrolytic treatment voltage can be 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, 4V, 4.1V, 4.2V, 4.3V, 4.4V, or 4.5V, or any two of the above numbers.

[0275] In some embodiments of this application, the current density of the electrolysis process is 5 A / m. 2 Up to 500A / m 2 .

[0276] In some embodiments of this application, the electrolysis process is performed while the slurry is stirred at a speed of 50 rpm to 1000 rpm. For example, the stirring speed can be 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, or 1000 rpm, or any two of the above numbers. This allows the dissolution and electrolysis reactions to fully occur, thereby improving the recovery efficiency.

[0277] The recycling method of this application includes the above steps (2) and (3). During the recycling process, electrolysis can generate sulfuric acid. This self-sustaining process can reduce the use of sulfuric acid in the recycling process and reduce the recycling cost. In addition, the dissolution reaction and the electrolysis reaction work together. The added positive electrode powder consumes sulfuric acid through the dissolution reaction, so that the electrolysis reaction continues to proceed within a suitable pH range. The electrolysis reaction will generate sulfuric acid, which maintains the recycling of sulfuric acid. At the same time, it can continuously dissolve the newly added positive electrode powder so that the dissolution reaction continues, reducing the use of sulfuric acid and avoiding the introduction of excess alkaline impurities, further reducing the recycling cost, and continuously recovering elements in the positive electrode material.

[0278] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt added to the cathode product during the electrolysis process is m1, positive electrode powder and reducing agent are added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0 or 0.1m0, or between any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, the positive electrode powder and reducing agent are added while the electrolysis reaction is underway, which is beneficial for achieving continuous recovery. As another example, m1 = 0.1m0, that is, when a certain amount of product is produced at the cathode, the positive electrode powder and reducing agent are added.

[0279] In some embodiments of this application, the amount of added cathode powder is determined based on the amount of nickel and / or cobalt produced by electrolysis, and the total amount of nickel and / or cobalt contained in the added cathode powder is the same as the amount of nickel and cobalt metal produced. Specifically, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt in the added cathode powder is N2, where 0.95N1≤N2≤1.05N1. For example, N2 can be 0.95N1, 0.96N1, 0.97N1, 0.98N1, 0.99N1, N1, 1.01N1, 1.02N1, 1.03N1, 1.04N1, or 1.05N1, or any two of the above numbers. The amount of reducing agent added is determined based on the total amount of metals (e.g., at least one of nickel, cobalt, and manganese) to be reduced in the added cathode powder. Specifically, the total molar amount of the second metal element in the added positive electrode powder is N3, and the molar amount of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3. For example, N4 can be 0.25N3, 0.5N3, 0.75N3, 1N3, 1.25N3, 1.5N3, 1.75N3, 2N3, 2.25N3, 2.5N3, 2.75N3, or 3N3, or any two of the above numbers. By adjusting N3 and N4 to meet the above ranges, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so as to ensure the continuous operation of the electrolysis process.

[0280] In some embodiments of this application, when the mass of nickel and / or cobalt added to the cathode product is m1, positive electrode powder, reducing agent, and sulfuric acid are added; wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0, or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, the positive electrode powder, reducing agent and sulfuric acid are added while the electrolysis reaction is taking place, which is beneficial to achieving continuous recovery. As another example, m1 = 0.1m0, that is, when a certain amount of product is produced at the cathode, the positive electrode powder, reducing agent and sulfuric acid are added.

[0281] In some embodiments of this application, the total molar amount of the first metal element in the added positive electrode powder is N5, the total molar amount of the added sulfuric acid is N6, and the total molar amount of the first metal element in the added reducing agent is N7. Surprisingly, using this process, the amount of added sulfuric acid only needs to meet the requirement of the first metal element, eliminating the need for large quantities of sulfuric acid.

[0282] Specifically, when the reducing agent does not contain sulfur (S), i.e., the reducing agent is selected from hydrogen peroxide, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and the reducing agent. This satisfies 0.9×(0.5N5+0.5N7)≤N6≤1.1×(0.5N5+0.5N7). For example, N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, and N7 to satisfy the above relationship, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so that the electrolysis process can continue.

[0283] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, and sodium metabisulfite, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and reducing agent, as well as the amount of sulfur in the reducing agent. The number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7). Here, the number of moles of sulfuric acid added is expressed as the number of moles of H2SO4. For example, N8+N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, N7, and N8 to satisfy the above relationship, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so that the electrolysis process can continue.

[0284] In some embodiments of this application, in step (3), the anode and cathode in the electrolysis process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0285] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T3 of the high-temperature treatment can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C, or any two of the above numbers. For example, the time t3 of the high-temperature treatment can be 0.1h, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h, or any two of the above numbers. The positive electrode current collector and positive electrode material layer obtained from disassembly are separated. The positive electrode material layer is then crushed and sieved to prepare positive electrode material layer powder within a certain particle size range. Subsequently, the positive electrode material layer powder is subjected to high-temperature treatment to remove the conductive agent and binder, thereby obtaining the positive electrode powder. This application does not impose any particular limitation on the particle size of the positive electrode material layer powder, as long as it achieves the purpose of this application. For example, the volume average particle size of the positive electrode material layer powder can be from 10 μm to 300 μm.

[0286] The disclosed method can further process the slurry from the electrolysis reaction process to obtain a filtrate containing Li₂SO₄ or Na₂SO₄. This method mainly corresponds to situations where the overall reaction of dissolution and electrolysis does not consume sulfuric acid, or where sulfuric acid is added during electrolysis, meaning that electrolysis can continue. For example, when using pretreated cathode powder mixed with SO₂ and sulfuric acid to prepare the slurry, since the overall reaction does not consume sulfuric acid, the electrolysis process can continue until the concentration of lithium or sodium ions in the solution meets the preset conditions. Alternatively, hydrogen peroxide can be used as a reducing agent, but sulfuric acid can be added appropriately during electrolysis to keep the total amount of nickel and cobalt ions in the solution constant. The Li₂SO₄ or Na₂SO₄ generated by electrolysis has a certain solubility in the slurry. When electrolysis continues, the concentration of lithium sulfate or sodium sulfate in the solution continuously increases until the set conditions are met. At this point, a portion of the slurry is discharged and filtered to obtain a filtrate containing Li₂SO₄ or Na₂SO₄ and cathode powder. The filtrate can be concentrated and crystallized to obtain lithium sulfate or sodium sulfate crystals. The concentrated mother liquor needs to be returned to the electrolysis slurry for further electrolysis to maintain the dynamic balance of nickel and cobalt ion concentrations in the slurry. This method is used to recover lithium or sodium.

[0287] In some embodiments of this application, the discharged electrolytic slurry is filtered to obtain filter residue (unreacted cathode powder) and a filtrate containing the first metal element. The filtrate is then purified to obtain a salt containing the first metal element and a mother liquor. In this application, the electrolytically treated slurry is the slurry discharged during the electrolytic process, i.e., the electrolytic slurry. The salt containing the first metal element obtained after purifying the filtrate can be a lithium salt or a sodium salt, thereby achieving the recovery of the first metal element.

[0288] In some embodiments of this application, the filter residue (unreacted cathode powder) obtained from filtration is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely reacted / recovered during the electrolytic reaction, and the filter residue may still contain the target metal, i.e., the first metallic element and / or the second metallic element. Adding the filter residue to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process.

[0289] In some embodiments of this application, sodium or lithium is selected as the first metal element. The purification process involves concentration and crystallization. The filtrate is then concentrated and crystallized to obtain a concentrated mother liquor and a salt containing the first metal element, i.e., a sodium salt or lithium salt, thereby achieving the recovery of the first metal element. The concentrated mother liquor is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely recovered during the concentration and crystallization process, and the concentrated mother liquor may still contain the target metal, primarily Ni and / or Co. Adding the concentrated mother liquor to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process. More importantly, the Ni and / or Co elements in the concentrated mother liquor can help maintain the ion concentration of Ni and / or Co elements in the slurry liquid phase within a relatively constant range. Furthermore, the return of the concentrated mother liquor can stabilize the liquid level in the electrolytic cell. Therefore, returning it to the slurry ensures that the electrolytic reaction can continue uninterrupted, thus facilitating continuous recovery.

[0290] In some embodiments of this application, the first metallic element is selected from lithium. The purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. After carbonization deposition, the filtrate yields a lithium-containing salt, a nickel-containing and / or cobalt-containing salt, and a mother liquor, thereby achieving lithium recovery. After lithium extraction using carbonization deposition, elements such as nickel / cobalt will also be deposited in solid form (e.g., nickel carbonate, cobalt carbonate). At this point, nickel / cobalt carbonate can be separated from lithium carbonate, and then the nickel and cobalt carbonate can be returned to the slurry. By using acid to dissolve the nickel / cobalt carbonate, the recovery rate of nickel and cobalt can be improved. More importantly, the acid-dissolved nickel / cobalt elements can keep the ion concentration of Ni and / or Co elements in the liquid phase of the slurry within a relatively constant range to ensure that the electrolysis reaction can continue without stopping. Moreover, returning the sedimentation mother liquor can also keep the liquid level in the electrolytic cell stable. However, it is best to remove the sodium sulfate in the sedimentation mother liquor before returning it to the slurry, which can improve the purity of the lithium salt obtained from lithium extraction. Of course, the sodium can be removed after the sodium in the mother liquor has accumulated to a certain extent.

[0291] In the solution provided by this process, when the first metal element is lithium, if sodium is introduced into the system, for example, if the reducing agent contains sodium or sodium carbide is used during lithium extraction, the subsequent discharged electrolytic slurry should preferably be extracted using carbonization deposition. This can better separate lithium and sodium and improve the purity of the extracted lithium. When the mother liquor after lithium extraction is returned to the slurry, it is best to remove the sodium from the mother liquor.

[0292] Sodium removal from the mother liquor can generally be achieved by evaporating and crystallizing the mother liquor before returning it to the system, separating most of the sodium as sodium sulfate. The remaining mother liquor is then returned to the system to improve lithium recovery. This process does not strictly limit the method of sodium removal from the mother liquor; those skilled in the art can choose appropriate methods based on actual needs.

[0293] This process uses slurry electrolysis and concentration crystallization or carbonization deposition to separate and extract valuable metals from the cathode materials of spent batteries. The acid generated during slurry electrolysis to separate nickel and cobalt can continuously dissolve the cathode powder in the solid phase of the slurry, enriching lithium while separating nickel and cobalt, greatly reducing the amount of acid used. The resulting lithium-rich filtrate can be purified to obtain high-purity lithium carbonate or lithium sulfate. By adding cathode powder, reducing agent, and optionally sulfuric acid during electrolysis, the slurry electrolysis can be carried out continuously without interruption, thus achieving a high recovery rate of valuable metals.

[0294] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0295] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0296] In some embodiments of this application, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as the reducing agent, undergoes the following dissolution reactions:

[0297] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2;

[0298] Electrolysis reactions include:

[0299] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0300] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0301] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0302] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4;

[0303] The elemental nickel and cobalt generated during electrolysis can act as catalysts, partially decomposing hydrogen peroxide into water and oxygen, specifically: 2H₂O₂=2H₂O+O₂; thus, the overall reaction is:

[0304] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0305] As can be seen from the above reaction formula, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as a reducing agent, during the dissolution reaction, although Co, Ni, and Mn consume SO4... 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Li consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0306] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0307] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0308] In some embodiments of this application, the positive electrode powder comprises NaNiO2, with sodium metabisulfite (Na2S2O5) as a reducing agent, and its dissolution reaction includes:

[0309] 4NaNiO2+Na2S2O5+5H2SO4=3Na2SO4+5H2O+4NiSO4;

[0310] Electrolysis reactions include:

[0311] 2NiSO4+2H2O=2Ni+2H2SO4+O2;

[0312] The overall reaction is:

[0313] 4NaNiO2+Na2S2O5+H2SO4=4Ni+H2O+2O2+3Na2SO4.

[0314] As can be seen from the above reaction formula, the positive electrode powder includes NaNiO2, and sodium metabisulfite is used as a reducing agent. During the dissolution reaction, Ni consumes SO4. 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Na consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0315] Specifically, as shown in Table 1.1, two specific implementation schemes of this application are listed:

[0316] Table 1.1

[0317] Note: "Black powder" in Table 1.1 refers to positive electrode powder.

[0318] In some embodiments of this application, sodium thiosulfate, sodium sulfite, and sodium metabisulfite are similar to those used for hydrogen peroxide in Table 1.1.

[0319] For the scheme of this application that involves continuous electrolysis without stopping:

[0320] 1) When SO2 is used as both a reducing agent and a source of sulfur, the overall system does not consume sulfuric acid. Therefore, only SO2 and positive electrode powder need to be added during the electrolysis process, which can make the slurry electrolysis reaction continue. Only a portion of the slurry in the electrolysis needs to be discharged periodically, and the purified concentrated mother liquor can be returned to the slurry.

[0321] 2) For other reducing agents, such as H2O2, sodium thiosulfate, sodium sulfite, and sodium metabisulfite, the total reaction of the system consumes sulfuric acid. Therefore, sulfuric acid + reducing agent + positive electrode powder need to be added during the electrolysis process to keep the slurry electrolysis reaction going. Only a portion of the slurry in the electrolysis needs to be discharged periodically, and the purified concentrated mother liquor can be returned to the slurry.

[0322] In this process, the slurry is periodically discharged to remove Li. + Or Na + Because of the Li in the slurry during the electrolysis process + Or Na + The amount will increase, and after saturation, precipitation will occur, affecting electrolysis and causing the release of Li+ or Na+. + This allows electrolysis to continue; Co in the slurry 2+ And / or Ni 2+ Some of the Co in the system is also lost during the discharge of the slurry. 2+ And / or Ni 2+ The reduced content necessitates returning the purified concentrated mother liquor to the slurry because the purified concentrated mother liquor contains Ni. 2+ and / or Co 2+ It also contains a high concentration, therefore, after returning, the Ni in the slurry... 2+ and / or Co 2+ The concentration is kept in dynamic equilibrium, allowing electrolysis to continue.

[0323] In this process, because the electrolysis process is continuous (the entire process takes a long time and can continue without stopping), a reducing agent (such as hydrogen peroxide) needs to be added continuously, which may cause changes in the volume of the slurry. In addition, the high temperature during the electrolysis process will also cause evaporation, which will affect the volume. In order to maintain the continuous electrolysis, it is necessary to keep the volume of the system relatively constant. If the volume of the system increases, the mother liquor obtained after lithium or sodium extraction from the discharged slurry can be evaporated, concentrated, and then returned. If the volume of the system decreases, water is added to the slurry.

[0324] In summary, by periodically draining a portion of the slurry from the electrolysis process, replenishing raw materials (positive electrode powder, reducing agent, and optional sulfuric acid), and returning the concentrated mother liquor and black powder, the slurry in the electrolysis process can be kept in order to maintain the Ni content. 2+ and / or Co 2+The concentration, lithium ion concentration, and slurry solid content are kept constant within a certain range to maintain a dynamic balance, thus enabling the electrolysis process to continue sustainably, making it suitable for large-scale industrial production.

[0325] The recycling method provided in this application uses dissolution, electrolysis, and crystallization / carbonization deposition to separate, extract, and recover valuable metals, namely the first and second metallic elements, from waste battery cathode powder. Electrolysis separates metals such as nickel and cobalt contained in the initial acidic slurry. Because the sulfuric acid produced by the electrolysis reaction can be used to further dissolve more cathode powder in the slurry, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and efficient. Simultaneously, the sulfuric acid produced by electrolysis and the added sulfuric acid dissolve more cathode powder, allowing the dissolution reaction to continue. Moreover, during electrolysis, a portion of the slurry is discharged, and the mother liquor obtained after lithium extraction is returned to the slurry for further electrolysis. This ensures that the ion concentrations of Li, Ni, and / or Co elements in the slurry liquid phase are dynamically maintained within a relatively constant range to sustain the continuous electrolysis reaction. Therefore, the electrolysis and dissolution reactions can proceed simultaneously and continuously during the recycling process, achieving continuous recycling and improving recovery rate and production capacity. In addition, the entire recycling process is simple, economical and efficient, and reduces environmental impact by reducing the use of acids and alkalis, making it an environmentally friendly recycling method.

[0326] This application also provides a method for recycling the positive electrode of waste batteries, which reduces the amount of sulfuric acid used in the recycling process, thereby lowering recycling costs. Furthermore, by adding positive electrode powder and a reducing agent, the electrolysis process can be continued for a period of time before stopping. Therefore, a single electrolysis process can process a large amount of waste battery positive electrode powder, enabling large-scale industrialization. This application focuses on the process of stopping electrolysis after a certain period of time. This is mainly because adding only positive electrode powder and a reducing agent during the feeding process necessitates stopping the system, as will be explained in detail later. By setting different stop conditions for different systems, not only can the electrolysis be fully carried out, improving the recovery rate of valuable elements, but also the generation of other unnecessary products can be avoided. The specific technical solution is described below:

[0327] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0328] (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0329] (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry, wherein the slurry contains a solid phase and a liquid phase, wherein the solid phase includes the positive electrode powder that has not undergone the dissolution reaction; the reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate and sodium metabisulfite.

[0330] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, the positive electrode powder and the reducing agent are added to the slurry. When the preset conditions are reached, the electrolytic treatment is stopped to obtain the anode product, the cathode product and the electrolytically treated slurry. The cathode product includes nickel and / or cobalt, and the electrolytically treated slurry is the slurry after the electrolysis is completed.

[0331] Wherein, the reducing agent is selected from sulfur dioxide, and the preset condition is: during the electrolysis process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation; or...

[0332] The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the preset condition is any one of the following:

[0333] (a) During the electrolytic treatment process, the ion concentration of the second metal element in the slurry is less than or equal to 0.05 wt%;

[0334] (b) During the electrolytic treatment, the current density is less than or equal to 8 mA / cm². 2 ;

[0335] (c) During the electrolytic treatment process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation.

[0336] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0337] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0338] In some embodiments of this application, step (2) includes: mixing at least the positive electrode powder, sulfuric acid, reducing agent, and water to undergo a dissolution reaction to obtain a slurry, wherein the slurry contains a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone a dissolution reaction; the temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6; the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

[0339] In some embodiments of this application, in step (3), the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5.

[0340] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt added to the cathode product is m1, the cathode powder and the reducing agent are added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0341] In some embodiments of this application, the total number of moles of nickel and / or cobalt added to the cathode product is N1, the total number of moles of nickel and / or cobalt added to the cathode powder is N2, and 0.95N1≤N2≤1.05N1; the total number of moles of the second metal element added to the cathode powder is N3, and the total number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0342] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0343] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0344] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4; wherein, when the reducing agent does not contain S element, it satisfies 0.9╳(0.5P1+P2+0.5P4)≤P3≤1.1╳(0.5P1+P2+0.5P4); or, when the reducing agent contains S element, the number of moles of S element in the reducing agent is P5, satisfying 0.9╳(0.5P1+P2+0.5P4)≤P3+P5≤1.1╳(0.5P1+P2+0.5P4); wherein, the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0345] In some embodiments of this application, after the electrolysis is completed, the slurry is filtered to obtain filter residue and filtrate containing the first metal element, and the filtrate is purified to obtain salt containing the first metal element.

[0346] In some embodiments of this application, the filter residue is added to the next slurry for further electrolytic treatment.

[0347] In some embodiments of this application, the first metal element is selected as sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element.

[0348] In some embodiments of this application, the concentrated mother liquor is added to the next slurry for further electrolysis.

[0349] In some embodiments of this application, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate is subjected to carbonization deposition to obtain a lithium-containing salt and a deposition mother liquor. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide.

[0350] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0351] In some embodiments of this application, in step (3), the anode and cathode in the electrolytic process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0352] In some embodiments of this application, in step (3), the anode product includes manganese dioxide.

[0353] In some embodiments of this application, the preset condition is that the concentration of the salt corresponding to the first metal element in the slurry reaches saturation, satisfying the condition 0.95n≤m≤n; wherein, the theoretical saturation concentration of the salt corresponding to the first metal element in the slurry is n, and the actual concentration of the salt corresponding to the first metal element in the slurry is m.

[0354] The recycling method provided in this application is used to recover valuable metals, namely the first and second metallic elements, from the positive electrode powder of spent batteries. Metals such as nickel and cobalt contained in the initial acidic slurry are separated by electrolysis. Because the sulfuric acid produced by the electrolysis reaction can be used to continue dissolving more positive electrode powder in the slurry until the sulfuric acid is exhausted and electrolysis stops, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and efficient. In addition, the recycling method provided in this application can also perform a continuous electrolysis process, because the sulfuric acid produced by electrolysis can dissolve more positive electrode powder, increasing the amount of positive electrode powder processed, thereby improving the recovery rate and production capacity, and enabling large-scale industrialization. Therefore, the entire recycling process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method.

[0355] In this process, the dissolution and electrolysis of the cathode powder take place in the same electrolytic cell / container or connected containers. This allows the H2SO4 generated during electrolysis to continuously dissolve newly added cathode powder, ensuring full utilization of sulfuric acid and reducing acid consumption. The amount of sulfuric acid used in this process is significantly reduced compared to traditional processes. Specifically, in traditional recovery processes, when sulfuric acid is used, elements such as Li, Na, Co, Ni, and Mn in the cathode powder all need to react with SO4. 2- The recovery of elements requires a combination of factors. If calculated using sulfur (S), 2 mol of Li corresponds to 1 mol of S, 2 mol of Na corresponds to 1 mol of S, and 1 mol of Co / Ni / Mn corresponds to 1 mol of S. In other words, the molar amount of S needs to match the total molar amount of Li, Na, Co, Ni, and Mn. Therefore, a large amount of sulfuric acid is consumed during the recovery process, increasing the recovery cost. However, in this process, only the molar amount of S corresponding to the molar amount of Li is needed, reducing the overall demand for S, or in other words, reducing the demand for sulfuric acid or acidic substances, thereby lowering the recovery cost. The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0356] (1) Disassemble waste batteries to obtain positive electrode, pre-treat the positive electrode to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt and manganese;

[0357] (2) At least positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate and sodium metabisulfite.

[0358] (3) Electrolyze the slurry, add positive electrode powder and reducing agent to the slurry during the electrolysis process, and stop the electrolysis when the preset conditions are met to obtain the anode product, the cathode product and the electrolyzed slurry; the cathode product includes nickel and / or cobalt, and the electrolyzed slurry is the slurry after the electrolysis is completed.

[0359] The recycling method provided in this application involves carrying out the dissolution reaction and electrolysis process in the same or connected containers. On one hand, by adding positive electrode powder and a reducing agent, the sulfuric acid generated during the electrolysis process can continuously dissolve the undissolved positive electrode powder in the slurry, allowing the dissolution reaction and electrolysis to proceed simultaneously and continuously for a period of time. Furthermore, no additional sulfuric acid needs to be added during the continuous reaction; electrolysis can be stopped only when the initially added sulfuric acid is nearly exhausted, improving the utilization rate of sulfuric acid. Alternatively, electrolysis can be stopped when the concentration of the salt corresponding to the first metal element reaches saturation. On the other hand, the sulfuric acid generated during the electrolysis process reduces the actual consumption of SO4. 2- SO4 consumed only for the first metallic element in the cathode powder 2- That is, the overall reaction only needs to provide Li + Or Na + Required SO4 2- That is, compared to traditional recycling processes that simultaneously consume both the first and second metal elements (SO4), 2- Technical solution: The SO4 recycling method of this application 2- The consumption of sulfuric acid is greatly reduced, thus reducing the demand for sulfuric acid. Consequently, the amount of sulfuric acid required throughout the recycling process is significantly reduced, lowering recycling costs. Furthermore, no harmful gases are generated during the entire recycling process, making it an environmentally friendly recycling method.

[0360] In this process, electrolysis needs to be stopped after a period of time. 1) When the reducing agent is sulfur dioxide, although the overall reaction of the system does not consume sulfuric acid, sulfur dioxide will provide S element to act as a sulfur source and react with Li. + Or Na + However, as electrolysis progresses, the amount of Li₂SO₄ or Na₂SO₄ in the slurry will increase to a saturated state and precipitate out, thus making continuous electrolysis impossible. Therefore, when SO₂ acts as a reducing agent, the termination condition for electrolysis is that the concentration of the salt corresponding to the first metal element in the slurry reaches saturation. 2) When the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, the overall reaction of the system will consume sulfuric acid, that is, SO₄²⁻ in the sulfuric acid will be released. 2- Gradually being Li + Or Na +As sulfuric acid is consumed, it participates in the overall reaction of the entire system, and its content gradually decreases. At this point, the system becomes unstable, for example, with Co. 2+ / Ni 2+ The content of [unspecified substance] will gradually decrease, the current density will decrease, and so on. Of course, the content of Li2SO4 or Na2SO4 will also increase. In fact, these changes occur simultaneously. Therefore, any one of them can be chosen as the condition for terminating electrolysis. The following is a detailed explanation:

[0361] In some embodiments of this application, the reducing agent is selected from sulfur dioxide. On the one hand, when SO2 is used as a reducing agent, it can also act as a source of sulfur ("S"), converting it into SO4 during the electrolytic treatment process. 2- This ensures that the overall system does not consume sulfuric acid, thus eliminating the need to replenish sulfuric acid during electrolysis and allowing the slurry electrolysis to continue for a period before stopping. Consequently, the demand for sulfuric acid is low throughout the entire recovery process, reducing recovery costs. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ ions in the sulfuric acid produced during electrolysis. + The reaction proceeds to maintain the pH value within a range suitable for normal electrolysis (because the SO2 system itself does not consume sulfuric acid, its slurry system is relatively stable with minimal pH fluctuations). Excessively high or low pH values ​​during electrolysis will affect its normal operation. Therefore, this process utilizes the added positive electrode powder and reducing agent to continuously undergo dissolution and electrolysis reactions with the sulfuric acid generated during electrolysis, thus consuming the H2 produced during electrolysis. + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable. Therefore, by continuously adding positive electrode powder and reducing agent to react with the sulfuric acid produced during electrolysis, the pH of the slurry can be adjusted without adding alkali to regulate the pH during the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities. Simultaneously, as the electrolysis and dissolution reactions proceed, the content of the first metal element ion in the slurry gradually increases. When the concentration of its corresponding salt reaches saturation, the electrolysis reaction stops, and the element can be recovered. Therefore, when sulfur dioxide is selected as the reducing agent, the preset condition can be: during the electrolysis process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation. 。

[0362] In other embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite. When the above-mentioned reducing agents are selected, on the one hand, the overall reaction only requires the consumption of the first metallic element, such as Li. + The corresponding SO4 2- Electrolysis continues until the sulfuric acid is nearly depleted, which is different from the current technology where the first and second metal elements are consumed simultaneously in the production of SO4. 2- The technical solution reduces the amount of sulfuric acid required (especially for reducing agents such as sodium sulfite, sodium thiosulfate, and sodium metabisulfite, where the sulfuric acid requirement can be further reduced). On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ ions in the sulfuric acid produced during electrolysis. + The reaction process aims to maintain the pH value within a range suitable for normal electrolysis for a certain period. A pH value that is too high or too low will affect the normal operation of the electrolysis process. Therefore, in this process, the added positive electrode powder and reducing agent continuously undergo dissolution and electrolysis reactions with the sulfuric acid produced during electrolysis. This not only consumes the H₂ produced during electrolysis but also... + This process maintains the slurry pH within a range suitable for normal electrolytic treatment over a period of time, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, it achieves a stable Co / Ni ratio product at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable. Therefore, by continuously adding positive electrode powder and reducing agent to react with the sulfuric acid produced during electrolysis, the pH of the slurry electrolysis can be adjusted without adding alkali to adjust the pH during the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities. Simultaneously, as the electrolysis and dissolution reactions proceed, nickel and / or cobalt are produced at the cathode. After the reaction reaches a certain extent, Co produced by the dissolution of the positive electrode powder... 2+ And / or Ni 2+ The amount is less than the Co lost due to electrolysis. 2+ And / or Ni 2+ The amount of Co in the system 2+ And / or Ni 2+ As the concentration decreases, the content of the second metal element ions in the slurry gradually decreases, the electrolysis density gradually decreases, and at the same time, the content of the first metal element ions gradually increases. The sulfuric acid in the slurry is gradually consumed by the first metal element, causing the pH of the slurry to gradually increase. Therefore, when any of the following preset conditions are met, the electrolysis reaction stops, and the element recovery can be completed: (1) During the electrolysis process, the ion concentration of the second metal element in the slurry is less than 0.05 wt%; (2) During the electrolysis process, the current density is less than or equal to 8 mA / cm². 2(3) During the electrolytic treatment process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation.

[0363] In this application, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation, satisfying the condition 0.95n ≤ m ≤ n, where the theoretical saturation concentration of the salt corresponding to the first metal element in the slurry is n, and the actual concentration of the salt corresponding to the first metal element in the slurry is m. For example, m can be 0.95n, 0.96n, 0.97n, 0.98n, 0.99n, or n, or any two of the above numbers. In this application, when the first metal element is lithium, n can be from 335 g / L to 345 g / L, for example, n can be set to 340 g / L. When the first metal element is sodium, n is from 395 g / L to 405 g / L, for example, n can be set to 400 g / L.

[0364] In this process, pretreated positive electrode powder, sulfuric acid and reducing agent are mixed and dissolved to form a slurry. The slurry contains a solid phase, namely undissolved positive electrode powder, and a liquid phase composed of various substances obtained after the dissolution reaction, sulfuric acid, water and so on.

[0365] In some embodiments of this application, the cathode material includes LiMO2 or NaMO2, where M is selected from at least one of Ni, Co, and Mn. When the cathode material includes LiMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of Li2SO4, NiSO4, CoSO4, MnSO4, H2O, and H2SO4. When the cathode material includes NaMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of NiSO4, CoSO4, MnSO4, H2O, H2SO4, and Na2SO4.

[0366] In this application, a certain solid phase is always required in the slurry to avoid H+ precipitates due to the different rates of dissolution and electrolysis reactions. + To prevent the accumulation of substances and avoid situations where the pH value falls below the expected range.

[0367] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5. For example, the solid content W1 of the slurry can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or 6.5, or between any two of the above numbers.

[0368] By adjusting the pH of the slurry in step (2) within the above-mentioned range, the electrolysis process can proceed stably, because excessively high or low pH values ​​during electrolysis will affect the normal operation of the electrolysis process. For example, if the pH value is too low, H2 gas is easily generated during electrolysis, which will affect the electrolysis production of elemental metals; if the pH value is too high, there is a risk that the metal elements will form alkaline precipitates, which will also affect the normal operation of the electrolysis process.

[0369] By controlling the solid content W1 of the slurry in step (2) within the above range, the H+ content can be prevented from increasing due to the continuous generation of sulfuric acid during subsequent electrolytic treatment. + This buildup can negatively impact subsequent electrolytic processing. Specifically, because the pH value needs to be maintained within the range of 2 to 6.5 during electrolysis, and the electrolysis reaction usually occurs rapidly, it can produce a large amount of H2SO4 (H+) in a short period of time. + The dissolution reaction is relatively slow. If the cathode powder is completely dissolved throughout the entire process, the difference in reaction rates between the two reactions will lead to a higher H2O generation rate during electrolysis. + Unable to react with the positive electrode powder in time, resulting in H + Excessive accumulation causes the pH of the electrolytic slurry to drop, making it unsuitable for electrolysis (at which point the electrolysis product is H2 instead of metal), and electrolysis cannot continue. Conversely, when the slurry contains some undissolved cathode powder, although the dissolution reaction rate is still slow, the increased amount of reactants results in a higher H2 consumption per unit time. + Increasing the concentration of the slurry pH can maintain it within the required range, allowing electrolysis to continue for a period of time until the sulfuric acid is depleted or the concentration of the salt corresponding to the first metal element reaches saturation. In this process, subsequent feeding, i.e., adding positive electrode powder and reducing agent, can sustain electrolysis for a period of time, ensuring that the slurry always has a certain solids content.

[0370] In some embodiments of this application, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h. For example, the temperature T1 of the dissolution reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the time t1 of the dissolution reaction can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. By controlling the temperature T1 and time t1 of the dissolution reaction within the above range, it is beneficial to fully dissolve the cathode powder to obtain the slurry with the desired solid content.

[0371] In some embodiments of this application, in step (2), the sulfuric acid is commercially available concentrated sulfuric acid.

[0372] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0373] Specifically, when the reducing agent does not contain sulfur (S), that is, the reducing agent is selected from hydrogen peroxide. The condition 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4) must be met. For example, P3 can be 0.9 × (0.5P1 + P2 + 0.5P4), 0.92 × (0.5P1 + P2 + 0.5P4), 0.94 × (0.5P1 + P2 + 0.5P4), 0.95 × (0.5P1 + P2 + 0.5P4), 0.96 × (0.5P1 + P2 + 0.5P4), 0.98 × (0.5P1 + P2 + 0.5P4), 1 × The formulas are (0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above values. By adjusting the relationship between P1, P2, P3, and P4 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0374] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, the molar number of S in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4). For example, P3+P5 can be 0.9×(0.5P1+P2+0.5P4), 0.92×(0.5P1+P2+0.5P4), 0.94×(0.5P1+P2+0.5P4), 0.95×(0.5P1+P2+0.5P4), 0.96×(0.5P1+P2+0.5P4), 0.98×(0.5P1+P2+0.5P4), 1 ×(0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above numbers. By adjusting the relationship between P1, P2, P3, P4, and P5 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0375] In this scheme, sulfuric acid is used to dissolve most of the positive electrode powder. The amount of sulfuric acid added is only enough to dissolve the preset amount of positive electrode powder that needs to be dissolved. A small portion of the positive electrode powder must remain undissolved (i.e., to ensure that a certain solid content is maintained in the slurry). This ensures that the dissolution reaction can be fully carried out during subsequent continuous feeding and electrolysis, and avoids a decrease in the pH of the system. The pH of the electrolysis process can be maintained within a suitable range. The electrolysis process continues for a period of time until the sulfuric acid is nearly exhausted or the concentration of the salt corresponding to the first metal element reaches saturation before electrolysis is stopped.

[0376] In some embodiments of this application, step (2) includes: mixing at least positive electrode powder, sulfuric acid, a reducing agent, and water to undergo a dissolution reaction to obtain a slurry containing a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone a dissolution reaction; the temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6; the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide. For example, the temperature T1 of the dissolution reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the dissolution reaction time t1 can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. For example, the solid content W1 of the slurry can be 2g / L, 3g / L, 4g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 34g / L, 40g / L, 45g / L, or 50g / L, or any two of the above numbers. For example, the pH of the slurry can be 3, 3.5, 4, 4.5, 5, 5.5, or 6, or any two of the above numbers.

[0377] In some embodiments of this application, in step (3), positive electrode powder and reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.5. In some embodiments of this application, in step (3), positive electrode powder and reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. For example, the solid content W2 of the slurry can be maintained at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above figures. For example, the pH of the slurry can be maintained at 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or 6.5, or any two of these values. During electrolysis, maintaining the slurry pH within the range of 2 to 6.5 results in a faster electrolysis reaction rate, producing a greater amount of H₂SO₄ (H₂SO₄) in a shorter time. +An increase in pH will decrease the pH value, and if the pH is too low, it will affect the electrolysis reaction rate. Generally, the dissolution reaction rate is slower than the electrolysis reaction rate. Therefore, to maintain the slurry solid content W2 within the range of 1 g / L to 50 g / L, the amount of H₂ consumed per unit time... + Increasing the concentration of the positive electrode powder and reducing agent can maintain the pH of the slurry within the range of 2 to 6.5. This allows the solid content (W2) and pH of the slurry to remain within these ranges, enabling the dissolution and electrolysis reactions to continue for a period of time until the sulfuric acid is nearly depleted or the concentration of the salt corresponding to the first metal element reaches saturation. This also prevents the continuous generation of sulfuric acid from causing H+ ions to rise. + This accumulation can hinder the normal operation of the electrolytic process.

[0378] In some embodiments of this application, the electrolytic treatment temperature T2 is from 20°C to 95°C, and the voltage is from 2.5V to 4.5V. For example, the electrolytic treatment temperature T2 can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the electrolytic treatment voltage can be 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, 4V, 4.1V, 4.2V, 4.3V, 4.4V, or 4.5V, or any two of the above numbers.

[0379] In some embodiments of this application, the current density of the electrolysis process is 5 A / m. 2 Up to 500A / m 2 For example, the current density for electrolytic treatment can be 5 A / m. 2 10A / m 2 20A / m 2 25A / m 2 30A / m 2 35A / m 2 40A / m 2 50A / m 2 100A / m 2 150A / m 2 200A / m 2 250A / m 2 300A / m 2 350A / m 2 400A / m 2 450A / m 2 Or 500A / m 2, or between any two of the above numbers.

[0380] In some embodiments of this application, the electrolysis process is performed while the slurry is stirred at a speed of 50 rpm to 1000 rpm. For example, the stirring speed can be 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, or 1000 rpm, or any two of the above numbers. This allows the dissolution and electrolysis reactions to fully occur, thereby improving the recovery efficiency.

[0381] The recycling method of this application includes the above steps (2) and (3). During the recycling process, electrolysis can generate sulfuric acid. This self-sustaining process can reduce the use of sulfuric acid in the recycling process and reduce the recycling cost. In addition, the dissolution reaction and the electrolysis reaction work together. The added positive electrode powder consumes sulfuric acid through the dissolution reaction, so that the electrolysis reaction continues to proceed within a suitable pH range. The electrolysis reaction will generate sulfuric acid, which maintains the recycling of sulfuric acid. At the same time, it can continuously dissolve the newly added positive electrode powder so that the dissolution reaction continues, reducing the use of sulfuric acid and avoiding the introduction of excess alkaline impurities, further reducing the recycling cost, and continuously recovering elements in the positive electrode material.

[0382] In some embodiments of this application, in step (3), when the mass of nickel and / or cobalt added to the cathode product is m1, positive electrode powder and reducing agent are added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0 or 0.1m0, or between any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, the positive electrode powder and reducing agent are added while the electrolysis reaction is underway, which is beneficial for achieving continuous recovery. As another example, m1 = 0.1m0, that is, when a certain amount of product is produced at the cathode, the positive electrode powder and reducing agent are added.

[0383] In some embodiments of this application, the amount of added cathode powder is determined based on the amount of nickel and / or cobalt produced by electrolysis, and the total amount of nickel and / or cobalt contained in the added cathode powder is substantially the same as the amount of nickel and cobalt metal produced. Specifically, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt in the added cathode powder is N2, where 0.95N1≤N2≤1.05N1. For example, N2 can be 0.95N1, 0.96N1, 0.97N1, 0.98N1, 0.99N1, N1, 1.01N1, 1.02N1, 1.03N1, 1.04N1, or 1.05N1, or any two of the above numbers. The amount of reducing agent added is determined based on the total amount of metals (e.g., at least one of nickel, cobalt, and manganese) to be reduced in the added cathode powder. Specifically, the total molar amount of the second metal element in the added positive electrode powder is N3, and the molar amount of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3. For example, N4 can be 0.25N3, 0.5N3, 0.75N3, 1N3, 1.25N3, 1.5N3, 1.75N3, 2N3, 2.25N3, 2.5N3, 2.75N3, or 3N3, or any two of the above numbers. By adjusting N3 and N4 to meet the above ranges, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so that the electrolysis process can continue for a period of time until the sulfuric acid is nearly exhausted or the concentration of the salt corresponding to the first metal element reaches saturation before electrolysis is stopped.

[0384] In some embodiments of this application, in step (3), the anode and cathode in the electrolysis process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0385] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T3 of the high-temperature treatment can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C, or any two of the above numbers. For example, the time t3 of the high-temperature treatment can be 0.1h, 0.5h, 1h, 1.5h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h, or any two of the above numbers. The positive electrode current collector and positive electrode material layer obtained from disassembly are separated. The positive electrode material layer is then crushed and sieved to prepare positive electrode material layer powder within a certain particle size range. Subsequently, the positive electrode material layer powder is subjected to high-temperature treatment to remove the conductive agent and binder, thereby obtaining the positive electrode powder. This application does not impose any particular limitation on the particle size of the positive electrode material layer powder, as long as it achieves the purpose of this application. For example, the volume average particle size of the positive electrode material layer powder can be from 10 μm to 300 μm.

[0386] In some embodiments of this application, in step (3):

[0387] 1) For schemes where SO2 acts as both a reducing agent and a source of sulfur, an electrolysis cutoff condition can be set to prevent continuous electrolysis, such as removing Li from the slurry. + Or Na + Electrolysis stops when the concentration (or the salt corresponding to lithium / the salt corresponding to sodium) reaches saturation.

[0388] 2) For other reducing agents, electrolysis will terminate without the addition of sulfuric acid. The termination conditions can be, for example, a decrease in the concentration of nickel and / or cobalt ions in the slurry to a predetermined value, or a saturation concentration of lithium or sodium ions (or the corresponding salts of lithium / sodium), or an electrolysis current density less than or equal to 8 mA / cm². 2 .

[0389] The method disclosed in this process can further process the residual solution (i.e., the slurry after electrolysis) obtained after the electrolysis reaction to obtain a filtrate and filter residue containing the first metal element. This method is mainly for cases where electrolysis is not continuous, for example, after electrolysis, nickel and / or cobalt in the slurry are completely electrolyzed or the concentration is below a predetermined value. Afterwards, filtration yields undissolved positive electrode powder filter residue and a filtrate mainly composed of lithium sulfate or sodium sulfate. The filter residue filtered from the residual solution is reused. In some cases, the raw material is not completely reacted / recovered during the electrolysis reaction, and the filter residue may still contain the target metal. Reusing the filter residue in this step not only improves the final extraction rate of the target metal but also reduces solid waste during the extraction process. After filtration, sodium carbonate is added to the lithium-containing filtrate to obtain lithium carbonate, or the lithium-containing or sodium-containing filtrate is concentrated and crystallized to obtain lithium sulfate crystals or sodium sulfate crystals. If the battery is a lithium-ion battery, the lithium-containing filtrate contains dissolved lithium compounds because the recovered battery anode contains lithium. This step adds further value to the extraction process. Specifically:

[0390] In some embodiments of this application, after electrolysis, the slurry is filtered to obtain filter residue and filtrate containing the first metal element. The filtrate is then purified to obtain a salt containing the first metal element. The salt containing the first metal element obtained after purification of the filtrate can be a lithium salt or a sodium salt, thereby achieving the recovery of the first metal element.

[0391] In some embodiments of this application, the filter residue obtained from filtration can be added to the slurry for the next electrolysis cycle for further electrolytic treatment. Typically, the target metal is not completely reacted / recovered during the electrolysis reaction, and the filter residue may still contain the target metal, i.e., the first metallic element and / or the second metallic element. Adding the filter residue to the slurry for the next electrolysis cycle not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process.

[0392] In some embodiments of this application, the first metal element is selected from sodium or lithium. The purification process is concentrated crystallization. The filtrate is concentrated and crystallized to obtain concentrated mother liquor and salt containing the first metal element, that is, sodium salt or lithium salt, thereby realizing the recovery of the first metal element.

[0393] In some embodiments of this application, the concentrated mother liquor can be added to the slurry for the next electrolysis cycle for further electrolytic treatment. Typically, the target metal is not fully recovered during the concentration and crystallization process, and the concentrated mother liquor may still contain the target metal, primarily Ni and / or Co. Adding the concentrated mother liquor to the slurry for the next electrolysis cycle not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process.

[0394] In some embodiments of this application, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. The filtrate is carbonized and deposited to obtain a lithium-containing salt and a mother liquor, thereby achieving the recovery of lithium.

[0395] In some embodiments of this application, the first metal element is selected from lithium, the reducing agent is selected from sodium sulfite, sodium thiosulfate, or sodium metabisulfite, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The carbonizing agent is selected from sodium carbonate. The filtrate is carbonized and deposited to obtain a lithium-containing salt and a mother liquor, thereby achieving the recovery of lithium.

[0396] In some embodiments of this application, the mother liquor is collected and added to the slurry for electrolytic reaction in the next electrolytic treatment. Typically, the target metal is not fully recovered during carbonization deposition, and the mother liquor may still contain the target metal. Adding the mother liquor to the slurry for the next electrolysis not only improves the final recovery rate of the target metal but also reduces liquid waste during the recovery process.

[0397] This process uses slurry electrolysis and concentration crystallization or carbonization deposition to separate and extract valuable metals from the positive electrode materials of spent batteries. The acid generated during slurry electrolysis to separate nickel and cobalt can continuously dissolve the positive electrode powder in the solid phase of the slurry, enriching lithium while separating nickel and cobalt, significantly reducing acid consumption. The resulting lithium-rich filtrate can be purified to obtain high-purity lithium carbonate or lithium sulfate. During electrolysis, positive electrode powder and reducing agents are added, allowing slurry electrolysis to continue for a period of time until the sulfuric acid is depleted or the Li in the slurry is reduced. + Stop when the concentration reaches saturation and electrolysis can no longer proceed.

[0398] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0399] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0400] In some embodiments of this application, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as the reducing agent, undergoes the following dissolution reactions:

[0401] 10LiNi 0.5 Co 0.2 Mn 0.3O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2;

[0402] Electrolysis reactions include:

[0403] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0404] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0405] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0406] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4;

[0407] The elemental nickel and cobalt generated during electrolysis can act as catalysts, partially decomposing hydrogen peroxide into water and oxygen, specifically: 2H₂O₂=2H₂O+O₂; thus, the overall reaction is:

[0408] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0409] As can be seen from the above reaction formula, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as a reducing agent, during the dissolution reaction, although Co, Ni, and Mn consume SO4... 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Li... + SO4 was consumed 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0410] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0411] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0412] In some embodiments of this application, the positive electrode powder comprises NaNiO2, with sodium metabisulfite (Na2S2O5) as a reducing agent, and its dissolution reaction includes:

[0413] 4NaNiO2+Na2S2O5+5H2SO4=3Na2SO4+5H2O+4NiSO4;

[0414] Electrolysis reactions include:

[0415] 2NiSO4+2H2O=2Ni+2H2SO4+O2;

[0416] The overall reaction is:

[0417] 4NaNiO2+Na2S2O5+H2SO4=4Ni+H2O+2O2+3Na2SO4.

[0418] As can be seen from the above reaction formula, the positive electrode powder includes NaNiO2, with sodium metabisulfite as the reducing agent. During the dissolution reaction, Ni... 2+ Although it will consume SO4 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Na+ is produced. + SO4 was consumed 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0419] Specifically, as shown in Table 1.2, two specific implementation schemes of this application are listed:

[0420] Table 1.2

[0421] Note: "Black powder" in Table 1.2 refers to positive electrode powder.

[0422] In some embodiments of this application, sodium sulfite, sodium thiosulfate, and sodium metabisulfite are similar to those used for hydrogen peroxide in Table 1.2.

[0423] The recycling method provided in this application uses dissolution, electrolysis, and crystallization / carbonization deposition to separate, extract, and recover valuable metals, namely the first and second metallic elements, from waste battery cathode powder. Electrolysis separates metals such as nickel and cobalt contained in the initial acidic slurry. Because the sulfuric acid produced by the electrolysis reaction can be used to continue dissolving more cathode powder in the slurry until the sulfuric acid is depleted and electrolysis ends, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and efficient. In addition, the recycling method provided in this application can also perform continuous electrolysis, as the sulfuric acid produced by electrolysis can dissolve more cathode powder, thereby improving the recovery rate and production capacity. Therefore, the entire recycling process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method.

[0424] Example

[0425] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0426] Test methods and equipment:

[0427] Purity test:

[0428] Cathode products: Digested with acid and then analyzed by ICP using inductively coupled plasma mass spectrometry (ICP-MS).

[0429] Anode product: determined by potassium permanganate titration using a titrator.

[0430] Lithium sulfate crystals: Impurity elements were determined using ICP, and inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis.

[0431] Test of the nickel-cobalt ratio in cathode products:

[0432] The nickel-cobalt ratio of the sample was determined by ICP after acid digestion.

[0433] The methods used in this application are conventional testing methods in the art, and those skilled in the art can choose appropriate testing methods as needed. This application does not impose any limitations.

[0434] Example 1-1 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishment of hydrogen peroxide + positive electrode powder; not continuous)

[0435] Figure 1 is a flowchart of the experiment in Example 1-1. The specific steps are as follows:

[0436] (1) Disassemble the waste ternary 523 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder by stirring at T3 = 500℃ to remove the residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The stirring time is t3 = 1.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0437] (2) 1000g of positive electrode powder was added to 1475g of sulfuric acid solution (98% by mass). At the same time, 8000mL of 8% hydrogen peroxide was continuously stirred into the slurry at T1=80℃ and added dropwise as a reducing agent to form a slurry. The dissolution reaction time was t1=0.5h. The resulting slurry had a pH=5 and a solid content W1=5g / L. Among them, the total mass of nickel and cobalt in 1000g of positive electrode powder was m0=400g.

[0438] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 80℃. The voltage during the electrolysis process was 3.0V, corresponding to a current density of 20mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 4g of nickel-cobalt metal produced (m1), 10g of cathode powder (the nickel-cobalt content in the cathode powder of ternary 523 lithium-ion batteries is approximately 40wt%) and 80mL of 8% hydrogen peroxide are added. The dissolution reactions in the slurry include:

[0439] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+ 10O2

[0440] Electrolysis reactions include:

[0441] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0442] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0443] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0444] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0445] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into lithium sulfate after electrolysis. Specifically, in this embodiment, electrolysis is stopped when the total concentration of nickel and cobalt ions in the slurry is less than 0.05 wt%. The overall reaction is as follows:

[0446] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0447] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 5:2 and a purity of 99.8%. The anode product is manganese dioxide with a purity of 93.5%. The electrolyzed slurry (i.e., the slurry after electrolysis) is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. Excess sodium carbonate is added to the lithium-containing filtrate to precipitate lithium, yielding lithium carbonate crystals with a purity of 99.5%.

[0448] In this embodiment, it can be seen from the overall reaction that the overall system consumes H2SO4, which acts as a sulfur source and H2O2 as a reducing agent. The sulfur in H2SO4 is matched with the lithium in the cathode powder in a 1:2 molar ratio to form Li2SO4, that is, only the sulfur that combines with Li is needed, and the sulfur that combines with Co and Ni is not needed, thus reducing the amount of sulfur used. After sufficient electrolysis by feeding, electrolysis is stopped when the total concentration of nickel and cobalt ions is low, and the corresponding sulfuric acid also tends to be exhausted. Then, the slurry after electrolysis is treated by lithium carbide precipitation to obtain high-purity Li2CO3 crystals.

[0449] Examples 1-2 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: SO2 + positive electrode powder added, not continuous)

[0450] Figure 2 is a flowchart of the experiments in Examples 1-2. The specific steps are as follows:

[0451] (1) Disassemble the waste lithium cobalt oxide batteries, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 550℃ by introducing air to remove residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0452] (2) 5500g of positive electrode powder was added to a solution prepared by mixing 5050g of sulfuric acid solution (98% mass concentration) and 8L of purified water. Simultaneously, the mixture was continuously stirred at T1 = 90℃, and sulfur dioxide gas (flow rate 1800g / h) was introduced into the bottom of the slurry as a reducing agent to form a slurry. The dissolution reaction time was t1 = 1h. The resulting slurry had a pH of 3 and a solid content of W1 = 50g / L. The total mass of cobalt in the 5500g of positive electrode powder was m0 = 3300g.

[0453] (3) Using a titanium-based iridium-tantalum plate as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 4.0V, corresponding to a current density of 30mA / cm². 2 During electrolysis, positive electrode powder is continuously added and sulfur dioxide gas is introduced according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 1g of cobalt metal produced (m1), 1.67g of positive electrode powder (the cobalt content in the positive electrode powder of lithium cobalt oxide batteries is approximately 60wt%) is added and 0.7g of SO2 is introduced. The dissolution reactions in the slurry include:

[0454] 2LiCoO2+2H2SO4+SO2=Li2SO4+2CoSO4+2H2O

[0455] Electrolysis reactions include:

[0456] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0457] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the slurry reaches 330 g / L (close to the saturation concentration of Li2SO4 in the slurry), electrolysis is stopped. The overall reaction is as follows:

[0458] 2LiCoO2 + SO2 = Li2SO4 + 2Co + O2

[0459] The cathode plate yields cobalt metal with a purity of 99.8%. After filtration and electrolysis, the slurry yields filter residue (unreacted cathode powder) and a lithium-rich filtrate. The lithium-rich filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The concentrated mother liquor can be returned to the slurry for the next electrolysis, resulting in lithium sulfate crystals with a purity of 99.7%. The unreacted cathode powder can also be returned to the slurry for the next electrolysis.

[0460] In this embodiment, the entire system does not consume H2SO4. SO2 acts as both a sulfur source and a reducing agent. The sulfur in SO2 is matched with the lithium in the cathode powder in a 1:2 molar equivalent ratio to form Li2SO4. That is, only the amount of sulfur that combines with Li is needed, and the amount of sulfur that combines with Co is not needed, thus reducing the amount of sulfur used. During the electrolysis process, the concentration of Li+ in the slurry continuously increases. Electrolysis can be stopped when the concentration of Li+ approaches or reaches the saturation concentration. Afterward, the slurry after electrolysis is treated by evaporation and concentration to obtain high-purity Li2SO4.

[0461] Examples 1-3 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: replenish SO2 + positive electrode powder; continuous operation)

[0462] Figure 3 is a flowchart of the experiments in Examples 1-3. The specific steps are as follows:

[0463] This embodiment is similar to Embodiments 1-2, except that the electrolysis does not terminate and can continue, as detailed below:

[0464] Steps (1) to (3) are the same as in Examples 1-2, and step (4) is as follows:

[0465] (4) When the lithium sulfate concentration in the electrolytic slurry (i.e., the slurry in the electrolysis process) reaches 280 g / L, 20% of the volume fraction of the slurry in the electrolysis process is discharged, and the remaining slurry continues to undergo dissolution and electrolysis reactions.

[0466] The cathode plate yields cobalt metal with a purity of 99.85%. The filtered electrolytically treated slurry yields filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue is added to the continuously electrolytically treated slurry. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.7%. The concentrated mother liquor is returned to the continuously electrolytically treated slurry to maintain a dynamic equilibrium of the Co ion concentration in the slurry.

[0467] Examples 1-4 (Dissolution process: sulfuric acid + positive electrode powder + sodium sulfite; Electrolysis process: replenish sodium sulfite + positive electrode powder; not continuous)

[0468] (1) Disassemble the waste sodium nickelate battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder with air at T3 = 600℃ to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 0.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0469] (2) 220g of positive electrode powder was added to a solution prepared with 260g of sulfuric acid solution (98% mass concentration) and 0.8L of purified water, and purified water was continuously added to bring the slurry volume to 1.0L. Simultaneously, sodium sulfite was continuously added to the slurry as a reducing agent at T1 = 80℃ with continuous stirring. The dissolution reaction time was t1 = 0.5h. The resulting slurry had a pH of 5 and a solid content of W1 = 20g / L. The total mass of nickel in the 220g of positive electrode powder was m0 = 110 g.

[0470] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 2.0V, corresponding to a current density of 35mA / cm². 2 During electrolysis, positive electrode powder and sodium sulfite are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 10g of nickel metal produced (m1), 20g of positive electrode powder (the nickel content in the positive electrode powder of sodium nickelate batteries is approximately 50%) is added, and 11g of sodium sulfite is introduced. The dissolution reactions in the slurry include:

[0471] 2NaNiO2+Na2SO3+3H2SO4=2Na2SO4+3H2O+2NiSO4

[0472] Electrolysis reactions include:

[0473] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0474] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into sodium sulfate after electrolysis. In this embodiment, electrolysis is stopped when the sodium sulfate concentration in the slurry reaches 320 g / L. The overall reaction is as follows:

[0475] 2NaNiO2+Na2SO3+H2SO4=2Ni+H2O+O2+2Na2SO4

[0476] The cathode plate yields nickel metal with a purity of 99.5%. After filtration and cessation of electrolysis, the electrolyzed slurry yields filter residue and a sodium-containing filtrate. The sodium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain sodium sulfate crystals and a concentrated mother liquor; the sodium sulfate crystals have a purity of 99.5%.

[0477] Examples 1-5 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishing hydrogen peroxide + positive electrode powder + sulfuric acid, continuously)

[0478] Figure 4 is a flowchart of the experiments in Examples 1-5. The specific steps are as follows:

[0479] (1) Disassemble the waste ternary 811 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 550℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1h. Then, pass it through a 150-mesh sieve to obtain positive electrode powder.

[0480] (2) 500g of positive electrode powder was added to 750g of sulfuric acid solution (98% by mass). Simultaneously, at T1 = 50℃, 4500mL of 8% hydrogen peroxide was continuously stirred and added dropwise as a reducing agent to form a slurry. The slurry volume was adjusted to 6.2L using purified water. The dissolution reaction time was t1 = 1.5h. The resulting slurry had a pH of 6 and a solid content of W1 = 2g / L. The total mass of nickel and cobalt in the 500g of positive electrode powder was m0 = 272g.

[0481] (3) Using titanium-platinum electrodes as anode and cathode plates, the slurry was electrolyzed at T2 = 50℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 20mA / cm². 2 During electrolysis, cathode powder, hydrogen peroxide, and sulfuric acid are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 5g of nickel-cobalt metal produced (m1), 9.2g of cathode powder, 100mL of 8% hydrogen peroxide, and 4.73g of 98wt% H2SO4 are added. The dissolution reactions in the slurry include:

[0482] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+15H2SO4+15H2O2=5Li2SO4+8NiSO4+CoSO4+MnSO4+30H2O+10O2

[0483] Electrolysis reactions include:

[0484] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0485] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0486] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0487] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0488] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration reaches 300 g / L, 20% of the liquid phase of the electrolyzed slurry (i.e., the slurry in the electrolysis process) is discharged. The remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0489] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+5H2SO4+7H2O2=5Li2SO4+8Ni+Co+MnO2+12H2O+10O2

[0490] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 8:1 and a purity of 99.75%. The anode product is manganese dioxide with a purity of 93.3%. The filtered electrolytic slurry yields filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue is added to the slurry undergoing continuous electrolysis. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.85%. The concentrated mother liquor is returned to the slurry undergoing continuous electrolysis to maintain a dynamic balance of Co / Ni ion concentration in the slurry.

[0491] Comparative Example 1-1

[0492] (1) Disassemble the waste ternary 622 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 650℃ by introducing air to remove residual conductive agent and binder. The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0493] (2) 300g of positive electrode powder was added to 400g of sulfuric acid solution (mass concentration 98%). At the same time, the volume of the slurry was adjusted to 3L with pure water at T1=50℃ to form a slurry. The dissolution reaction time was t1=1h. The pH of the obtained slurry was 2 and the solid content was W1=0.1g / L.

[0494] (3) Using stainless steel as the cathode plate and lead-calcium alloy as the anode plate, the slurry was electrolyzed at T2 = 60℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 15mA / cm². 2 .

[0495] After about 15 minutes of electrolysis, the pH of the slurry dropped to 1, and obvious bubbles were generated on the cathode plate. This was because there was too little positive electrode powder in the slurry, which could not neutralize the acid produced by electrolysis, thus preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0496] In the recycling method described in this application, SO2 in Examples 1-2 simultaneously acts as both a sulfur source and a reducing agent. The sulfur in SO2 or sulfuric acid is matched with Li or Na in the positive electrode powder in a 1:2 molar equivalent ratio to form Li2SO4 or Na2SO4. That is, only the amount of sulfur required to combine with Li or Na is needed, and the amount of sulfur required to combine with Co, Ni, or Mn is not needed. Therefore, the amount of sulfur used is reduced, which also reduces the amount of sulfuric acid used, thereby reducing the recycling cost.

[0497] Li in the slurry during electrolysis + As the concentration increases, it can be achieved in Li + Electrolysis is stopped when the concentration approaches or reaches saturation, as in Examples 1-2; alternatively, positive electrode powder and reducing agent are continuously added for continuous electrolysis, as in Examples 1-3; or positive electrode powder, reducing agent, and sulfuric acid are continuously added for continuous electrolysis, as in Examples 1-5. The electrolyzed slurry is then treated by evaporation concentration or carbonization deposition to obtain high-purity Li₂SO₄. This achieves the recovery of Li, Na, Co, Ni, and Mn elements with high purity. In contrast, in Comparative Example 1-1, insufficient positive electrode powder in the slurry during electrolysis prevents the neutralization of the acid produced, leading to hydrogen gas generation and hindering normal electrolysis. The resulting product has low purity.

[0498] Example 2-1 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenish hydrogen peroxide + positive electrode powder + sulfuric acid, continuous process)

[0499] The specific steps are as follows:

[0500] (1) Disassemble the waste ternary 523 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder by stirring at T3 = 500℃ to remove the residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The stirring time is t3 = 1.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0501] (2) 1000g of positive electrode powder was added to 1475g of sulfuric acid solution (98% by mass). At the same time, 8000mL of 8% hydrogen peroxide was continuously stirred into the slurry at T1=80℃ and added dropwise as a reducing agent to form a slurry. The dissolution reaction time was t1=0.5h. The resulting slurry had a pH=5 and a solid content W1=5g / L. Among them, the total mass of nickel and cobalt in 1000g of positive electrode powder was m0=400g.

[0502] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 80℃. The voltage during the electrolysis process was 3.0V, corresponding to a current density of 25mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 10g of nickel-cobalt metal produced (m1), 23.5g of cathode powder (the nickel-cobalt content in the cathode powder of ternary 523 lithium-ion batteries is approximately 42.5wt%), 170mL of 8% hydrogen peroxide, and 12.16g of H2SO4 (98wt%) are added. The dissolution reactions in the slurry include:

[0503] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2

[0504] Electrolysis reactions include:

[0505] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0506] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0507] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0508] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0509] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the electrolyzed slurry (i.e., the slurry in the electrolysis process) reaches 320 g / L, 20% of the slurry in the electrolysis process is discharged by volume. The remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0510] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0511] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 5:2 and a purity of 99.74%. The anode product is manganese dioxide with a purity of 93.9%. The discharged electrolytic slurry is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.5%. The concentrated mother liquor is returned to the slurry undergoing continuous electrolysis to remove the Co. 2+ Ni 2+ The concentration is maintained in dynamic equilibrium and the system is stable; the filter residue (unreacted cathode powder) is returned to the slurry for electrolysis to improve the recovery rate.

[0512] In this embodiment, the overall reaction shows that the system consumes H2SO4, which acts as a sulfur source, while H2O2 acts as a reducing agent. The sulfur in H2SO4 reacts with the lithium in the cathode powder in a 1:2 molar ratio to form Li2SO4. This means only sulfur complexing with Li is needed, not with Co or Ni, thus reducing the amount of sulfur used. Continuous electrolysis is achieved through feeding, and as the lithium... + As the concentration increases, in order to prevent electrolysis from stopping, in Li + When the concentration of (or its corresponding salt) reaches the preset concentration, part of the slurry from electrolysis is discharged, so that the Li in the system... + The content is maintained at an appropriate level, and then the discharged electrolytic slurry is treated by evaporation and concentration to obtain high-purity Li2SO4. In addition, the concentrated mother liquor obtained after lithium extraction needs to be returned to the system to ensure stable and continuous electrolysis.

[0513] Example 2-2 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: replenish SO2 + positive electrode powder, continuous process)

[0514] Figure 3 is a flowchart of the experiment in Example 2-2. The specific steps are as follows:

[0515] (1) Disassemble the waste lithium cobalt oxide batteries, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 700℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0516] (2) 5500g of positive electrode powder was added to a solution prepared by mixing 5050g of sulfuric acid solution (98% mass concentration) and 8L of purified water. Simultaneously, the mixture was continuously stirred at T1 = 80℃, and sulfur dioxide gas (flow rate 1800g / h) was introduced into the bottom of the slurry as a reducing agent to form a slurry. The dissolution reaction time was t1 = 1.5h. The resulting slurry had a pH of 3 and a solid content of W1 = 50g / L. The total mass of cobalt in the 5500g of positive electrode powder was m0 = 3300g.

[0517] (3) Using a titanium-based iridium-tantalum plate as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 80℃. The voltage during the electrolysis process was 3.5V, corresponding to a current density of 25mA / cm². 2 During electrolysis, positive electrode powder is continuously added and sulfur dioxide gas is introduced according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 1g of cobalt metal produced (m1), 1.67g of positive electrode powder (the cobalt content in the positive electrode powder of lithium cobalt oxide batteries is approximately 60wt%) is added and 0.7g of SO2 is introduced. The dissolution reactions in the slurry include:

[0518] 2LiCoO2+2H2SO4+SO2=Li2SO4+2CoSO4+2H2O

[0519] Electrolysis reactions include:

[0520] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0521] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the electrolyzed slurry (i.e., the slurry in the electrolysis process) reaches 280 g / L, 20% of the slurry in the electrolysis process is discharged, and the remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0522] 2LiCoO2 + SO2 = Li2SO4 + 2Co + O2

[0523] The cathode plate yields cobalt metal with a purity of 99.87%. The discharged electrolytic slurry is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue is added to the slurry undergoing continuous electrolysis. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.65%. The concentrated mother liquor is returned to the slurry undergoing continuous electrolysis to reduce the Co content in the slurry. 2+ The concentration is maintained in dynamic equilibrium, and the system remains stable; the filter residue (unreacted cathode powder) is also returned to the continuously electrolyzed slurry to improve the recovery rate.

[0524] In this embodiment, the entire system does not consume H2SO4. SO2 simultaneously acts as a sulfur source and reducing agent. The sulfur in SO2 reacts with the lithium in the cathode powder in a 1:2 molar equivalent ratio to form Li2SO4. This means only the amount of sulfur needed to react with lithium is required, not the amount needed to react with co, thus reducing the amount of sulfur used. In this embodiment, no sulfur is needed during continuous electrolysis. The lithium in the slurry during electrolysis... + As the concentration increases, in order to ensure that electrolysis can continue uninterrupted, in Li + When the concentration of (or its corresponding salt) reaches the preset concentration, part of the slurry from electrolysis is discharged, so that the Li in the system... + The content is maintained at an appropriate level, and then the discharged electrolytic slurry is treated by evaporation and concentration to obtain high-purity Li2SO4. In addition, the concentrated mother liquor obtained after lithium extraction needs to be returned to the system to enable the system to continue electrolysis.

[0525] Examples 2-3 (Dissolution process: sulfuric acid + positive electrode powder + sodium sulfite; Electrolysis process: replenish sodium sulfite + positive electrode powder + sulfuric acid, continuously)

[0526] (1) Disassemble the waste sodium nickelate battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder with air at T3 = 600℃ to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 0.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0527] (2) 220g of positive electrode powder was added to a solution prepared with 260g of sulfuric acid solution (98% mass concentration) and 0.8L of purified water, and purified water was continued to be added until the slurry volume reached 1.0L. Simultaneously, sodium sulfite was continuously added to the slurry as a reducing agent at T1 = 80℃ with continuous stirring to form a slurry. The dissolution reaction time was t1 = 0.5h. The resulting slurry had a pH of 5 and a solid content of W1 = 20g / L. The total mass of nickel in the 220g of positive electrode powder was m0 = 110g.

[0528] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 2.0V, corresponding to a current density of 35mA / cm². 2 During electrolysis, cathode powder and sodium sulfite are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 8g of nickel metal produced (m1), 16g of cathode powder (the nickel content in sodium nickelate battery cathode powder is approximately 50%), 8.8g of sodium sulfite, and 7.04g of H2SO4 (98wt%) are added. The dissolution reactions in the slurry include:

[0529] 2NaNiO2+Na2SO3+3H2SO4=2Na2SO4+3H2O+2NiSO4

[0530] Electrolysis reactions include:

[0531] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0532] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the electrolyzed slurry (i.e., the slurry in the electrolysis process) reaches 250 g / L, 10% of the slurry in the electrolysis process is discharged, and the remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0533] 2NaNiO2+Na2SO3+H2SO4=2Ni+H2O+O2+2Na2SO4

[0534] The cathode plate yields nickel metal with a purity of 99.1%. The discharged electrolytic slurry is filtered to obtain filter residue (unreacted cathode powder) and a sodium-containing filtrate. The sodium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain sodium sulfate crystals and a concentrated mother liquor. The sodium sulfate crystals have a purity of 99.3%. The concentrated mother liquor is returned to the continuously electrolyzing slurry to remove the Ni. 2+ The concentration is maintained in dynamic equilibrium; the filter residue (unreacted cathode powder) is returned to the slurry for electrolysis to improve the recovery rate.

[0535] Examples 2-4 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishing hydrogen peroxide + positive electrode powder + sulfuric acid, continuously)

[0536] Figure 4 is a flowchart of the experiments in Examples 2-4. The specific steps are as follows:

[0537] (1) Disassemble the waste ternary 811 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 650℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1.5h. Then pass it through a 150-mesh sieve to obtain positive electrode powder.

[0538] (2) 500g of positive electrode powder was added to 750g of sulfuric acid solution (98% by mass). Simultaneously, at T1 = 65℃, 4500mL of 8% hydrogen peroxide was continuously stirred and added dropwise as a reducing agent to form a slurry. The slurry volume was adjusted to 6.2L using purified water. The dissolution reaction time was t1 = 2.0h. The resulting slurry had a pH of 6 and a solid content of W1 = 2g / L. The total mass of nickel and cobalt in the 500g of positive electrode powder was m0 = 272g.

[0539] (3) Using titanium-platinum electrodes as anode and cathode plates, the slurry was electrolyzed at T2 = 65℃. The voltage during electrolysis was 3.0V, corresponding to a current density of 25mA / cm². 2 During electrolysis, cathode powder, hydrogen peroxide, and sulfuric acid are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 5g of nickel-cobalt metal produced (m1), 9.2g of cathode powder, 100mL of 8% hydrogen peroxide, and 4.73g of 98wt% H2SO4 are added. The dissolution reactions in the slurry include:

[0540] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+15H2SO4+15H2O2=5Li2SO4+8NiSO4+CoSO4+MnSO4+30H2O+10O2

[0541] Electrolysis reactions include:

[0542] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0543] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0544] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0545] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0546] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration reaches 300 g / L, 20% of the liquid phase of the electrolyzed slurry (i.e., the slurry in the electrolysis process) is discharged. The remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0547] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+5H2SO4+7H2O2=5Li2SO4+8Ni+Co+MnO2+12H2O+10O2

[0548] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 8:1 and a purity of 99.81%. The anode product is manganese dioxide with a purity of [missing information]. 93.9The electrolytically treated slurry discharged after filtration yields filter residue (unreacted cathode powder) and lithium-containing filtrate. The filter residue is added back to the slurry undergoing continuous electrolysis. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and concentrated mother liquor. The lithium sulfate crystals have a purity of 99.90%. The concentrated mother liquor is returned to the slurry undergoing continuous electrolysis to maintain a dynamic balance of Co / Ni ion concentration in the slurry. The filter residue (unreacted cathode powder) is further returned to the slurry for electrolysis to improve the recovery rate.

[0549] Comparative Example 2-1

[0550] (1) Disassemble the waste ternary 622 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 650℃ by introducing air to remove residual conductive agent and binder. The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0551] (2) 300g of positive electrode powder was added to 400g of sulfuric acid solution (mass concentration 98%). At the same time, the volume of the slurry was adjusted to 3L with pure water at T1=50℃ to form a slurry. The dissolution reaction time was t1=1h. The pH of the obtained slurry was 2 and the solid content was W1=0.1g / L.

[0552] (3) Using stainless steel as the cathode plate and lead-calcium alloy as the anode plate, the slurry was electrolyzed at T2 = 60℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 15mA / cm². 2 .

[0553] After about 15 minutes of electrolysis, the pH of the slurry dropped to 1, and obvious bubbles were generated on the cathode plate. This was because there was too little positive electrode powder in the slurry, which could not neutralize the acid produced by electrolysis, thus preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0554] The recovery method in this application embodiment achieves continuous recovery without interruption during electrolysis when the reducing agent is sulfur dioxide. This is achieved by adding positive electrode powder and sulfur dioxide, and then returning the filtered, purified, and treated mother liquor to the slurry for continued electrolysis, as in Example 2-2. Similarly, when the reducing agent is not sulfur dioxide but hydrogen peroxide or sodium sulfite, this is achieved by adding positive electrode powder, reducing agent, and sulfuric acid, and then returning the filtered, purified, and treated mother liquor to the slurry for continued electrolysis, as in Examples 2-1, 2-3, and 2-4. However, in Comparative Example 2-1, the solid content of the positive electrode powder in the slurry is too low during electrolysis to neutralize the acid produced, leading to the generation of hydrogen gas. This prevents the electrolysis process from proceeding normally and hinders continuous recovery.

[0555] Example 3-1 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishment of hydrogen peroxide + positive electrode powder; not continuous)

[0556] Figure 1 is a flowchart of the experiment in Example 3-1. The specific steps are as follows:

[0557] (1) Disassemble the waste ternary 523 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder by stirring at T3 = 650℃ to remove the residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The stirring time is t3 = 2h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0558] (2) 1000g of positive electrode powder was added to 1475g of sulfuric acid solution (98% by mass). At the same time, 8000mL of hydrogen peroxide with a mass concentration of 8% was continuously stirred into the slurry at T1 = 70℃ and added dropwise as a reducing agent to form a slurry. The dissolution reaction time was t1 = 1h. The resulting slurry had a pH of 5 and a solid content of W1 = 5g / L. Among them, the total mass of nickel and cobalt in 1000g of positive electrode powder was m0 = 400g.

[0559] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 70℃. The voltage during electrolysis was 3.5V, corresponding to a current density of 25mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 4g of nickel-cobalt metal produced (m1), 10g of cathode powder (the nickel-cobalt content in the cathode powder of ternary 523 lithium-ion batteries is approximately 40wt%) and 80mL of 8% hydrogen peroxide are added. The dissolution reactions in the slurry include:

[0560] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2

[0561] Electrolysis reactions include:

[0562] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0563] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0564] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0565] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0566] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into lithium sulfate after electrolysis. Specifically, in this embodiment, electrolysis is stopped when the total concentration of nickel and cobalt ions in the slurry is less than 0.05 wt%. The overall reaction is as follows:

[0567] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0568] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 5:2 and a purity of 99.88%. The anode product is manganese dioxide with a purity of 94.27%. The electrolyzed slurry (i.e., the slurry after electrolysis) is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. Excess sodium carbonate is added to the lithium-containing filtrate to precipitate lithium, yielding lithium carbonate crystals with a purity of 99.62%.

[0569] In this embodiment, it can be seen from the overall reaction that the overall system consumes H2SO4, which acts as a sulfur source and H2O2 as a reducing agent. The S in H2SO4 and Li in the cathode powder are matched in a 1:2 molar ratio to form Li2SO4, that is, only S that combines with Li is needed, and S that combines with Co and Ni is not needed, thus reducing the amount of S used. After sufficient electrolysis by feeding, electrolysis is stopped when the total concentration of nickel and cobalt ions is low, and the corresponding sulfuric acid also tends to be exhausted. Then, the slurry after electrolysis is treated by lithium carbide precipitation to obtain high-purity Li2CO3 crystals.

[0570] Example 3-2 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: supplement with SO2 + positive electrode powder, not continuous)

[0571] Figure 2 is a flowchart of the experiment in Example 3-2. The specific steps are as follows:

[0572] (1) Disassemble the waste lithium cobalt oxide batteries, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 700℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0573] (2) 5500g of positive electrode powder was added to a solution prepared by mixing 5050g of sulfuric acid solution (98% mass concentration) and 8L of purified water. Simultaneously, the mixture was continuously stirred at T1 = 85℃, and sulfur dioxide gas (flow rate 1800g / h) was introduced into the bottom of the slurry as a reducing agent to form a slurry. The dissolution reaction time was t1 = 1h. The resulting slurry had a pH of 3 and a solid content of W1 = 50g / L. The total mass of cobalt in the 5500g of positive electrode powder was m0 = 3300g.

[0574] (3) Using a titanium-based iridium-tantalum plate as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 85℃. The voltage during the electrolysis process was 4.0V, corresponding to a current density of 35mA / cm². 2 During electrolysis, positive electrode powder is continuously added and sulfur dioxide gas is introduced according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 1g of cobalt metal produced (m1), 1.67g of positive electrode powder (the cobalt content in the positive electrode powder of lithium cobalt oxide batteries is approximately 60wt%) is added and 0.7g of SO2 is introduced. The dissolution reactions in the slurry include:

[0575] 2LiCoO2+2H2SO4+SO2=Li2SO4+2CoSO4+2H2O

[0576] Electrolysis reactions include:

[0577] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0578] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the slurry reaches 330 g / L (close to the saturation concentration of Li2SO4 in the slurry), electrolysis is stopped. The overall reaction is as follows:

[0579] 2LiCoO2 + SO2 = Li2SO4 + 2Co + O2

[0580] The cathode plate yields cobalt metal with a purity of 99.8%. After filtration and electrolysis, the slurry yields filter residue (unreacted cathode powder) and a lithium-rich filtrate. The lithium-rich filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The concentrated mother liquor can be used in the slurry for the next electrolysis, yielding lithium sulfate crystals with a purity of 99.7%. The unreacted cathode powder can also be used in the slurry for the next electrolysis.

[0581] In this embodiment, the entire system does not consume H2SO4. SO2 acts as both a sulfur source and a reducing agent. The sulfur in SO2 is matched with the lithium in the cathode powder in a 1:2 molar equivalent ratio to form Li2SO4. That is, only the amount of sulfur that combines with Li is needed, and the amount of sulfur that combines with Co is not needed, thus reducing the amount of sulfur used. During the electrolysis process, the concentration of Li+ in the slurry continuously increases. Electrolysis can be stopped when the concentration of Li+ approaches or reaches the saturation concentration. Afterward, the slurry after electrolysis is treated by evaporation and concentration to obtain high-purity Li2SO4.

[0582] Example 3-3 (Dissolution process: sulfuric acid + positive electrode powder + sodium sulfite; Electrolysis process: sodium sulfite + positive electrode powder added; process is not continuous)

[0583] (1) Disassemble the waste sodium nickelate battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder with air at T3 = 750℃ to remove the residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0584] (2) 220g of positive electrode powder was added to a solution prepared with 260g of sulfuric acid solution (98% mass concentration) and 0.8L of purified water, and purified water was continuously added to bring the slurry volume to 1.0L. Simultaneously, sodium sulfite was continuously added to the slurry as a reducing agent at T1 = 70℃ with continuous stirring. The dissolution reaction time was t1 = 2h. The resulting slurry had a pH of 5 and a solid content of W1 = 20g / L. The total mass of nickel in the 220g of positive electrode powder was m0 = 110 g.

[0585] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 70℃. The voltage during the electrolysis process was 2.0V, corresponding to a current density of 25mA / cm². 2 During electrolysis, positive electrode powder and sodium sulfite are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 10g of nickel metal produced (m1), 20g of positive electrode powder (the nickel content in the positive electrode powder of sodium nickelate batteries is approximately 50%) is added, and 11g of sodium sulfite is introduced. The dissolution reactions in the slurry include:

[0586] 2NaNiO2+Na2SO3+3H2SO4=2Na2SO4+3H2O+2NiSO4

[0587] Electrolysis reactions include:

[0588] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0589] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into sodium sulfate after electrolysis. In this embodiment, electrolysis is stopped when the sodium sulfate concentration in the slurry reaches 320 g / L. The overall reaction is as follows:

[0590] 2NaNiO2+Na2SO3+H2SO4=2Ni+H2O+O2+2Na2SO4

[0591] Nickel metal with a purity of 99.91% was obtained from the cathode plate. The slurry after electrolysis was stopped was filtered to obtain filter residue and a sodium-containing filtrate. The sodium-containing filtrate was evaporated, concentrated, cooled, crystallized, and filtered to obtain sodium sulfate crystals and a concentrated mother liquor. The sodium sulfate crystals had a purity of 99.73%.

[0592] Examples 3-4 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishment of hydrogen peroxide + positive electrode powder; not continuous)

[0593] (1) Disassemble the waste ternary 811 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 550℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1h. Then, pass it through a 150-mesh sieve to obtain positive electrode powder.

[0594] (2) 100g of positive electrode powder was added to 150g of sulfuric acid solution (98% by mass). Simultaneously, at T1 = 55℃, 900mL of 8% hydrogen peroxide was continuously stirred and added dropwise as a reducing agent to form a slurry. The slurry volume was adjusted to 1.24L using purified water. The dissolution reaction time was t1 = 1.0h. The resulting slurry had a pH of 6 and a solid content of W1 = 2g / L. The total mass of nickel and cobalt in 100g of positive electrode powder was m0 = 54.4g.

[0595] (3) Using titanium-platinum electrodes as anode and cathode plates, the slurry was electrolyzed at T2 = 50℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 15mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 1g of nickel-cobalt metal produced (m1), 1.84g of cathode powder and 20mL of 8% hydrogen peroxide are added. The dissolution reactions in the slurry include:

[0596] 10LiNi 0.8 Co 0.1 Mn 0.1O2+15H2SO4+15H2O2=5Li2SO4+8NiSO4+CoSO4+MnSO4+30H2O+10O2

[0597] Electrolysis reactions include:

[0598] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0599] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0600] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0601] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0602] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry, when the current density of the electrolysis is lower than 8 mA / cm³. 2 When the electrolysis stops, the overall reaction is:

[0603] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+5H2SO4+7H2O2=5Li2SO4+8Ni+Co+MnO2+12H2O+10O2

[0604] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 8:1 and a purity of 99.85%. The anode product is manganese dioxide with a purity of 94.6%. The filtered electrolytic slurry yields filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue can be added to the slurry for the next electrolytic treatment. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.91%, and the concentrated mother liquor is added to the slurry for the next electrolytic treatment.

[0605] Examples 3-5 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishment of hydrogen peroxide + positive electrode powder; not continuous)

[0606] (1) Disassemble the waste ternary 622 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 700℃ by introducing air to remove residual conductive agent and binder. The pre-treatment time is t3 = 1h. After treatment, grind and pass through a 200-mesh sieve to obtain positive electrode powder.

[0607] (2) 2000g of positive electrode powder was added to 2784g of sulfuric acid solution (98% by mass). Simultaneously, at T1 = 70℃, 15000mL of 8% hydrogen peroxide was continuously stirred and added dropwise as a reducing agent to form a slurry. The dissolution reaction time was t1 = 2.0h. The resulting slurry had a pH of 5.5 and a solid content of W1 = 12g / L. The total mass of nickel and cobalt in the 2000g of positive electrode powder was m0 = 969g.

[0608] (3) Using a titanium plate as the anode plate and 316L stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 3.5V, corresponding to a current density of approximately 35mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 10g of nickel-cobalt metal produced (m1), 20.64g of cathode powder (the nickel-cobalt content in the cathode powder of ternary 622 lithium-ion batteries is approximately 48.45wt%) and 140mL of 8% hydrogen peroxide are added. The dissolution reactions in the slurry include:

[0609] 10LiNi 0.6 Co 0.2 Mn 0.2 O2+15H2SO4+15H2O2=5Li2SO4+6NiSO4+2CoSO4+2MnSO4+30H2O+10O2

[0610] Electrolysis reactions include:

[0611] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0612] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0613] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0614] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0615] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until the lithium sulfate concentration in the slurry reaches 300 g / L after electrolysis, at which point electrolysis is stopped. The overall reaction is as follows:

[0616] 10LiNi 0.6 Co 0.2 Mn 0.6 O2+5H2SO4+15H2O2=5Li2SO4+6Ni+2Co+2MnO2+20H2O+13O2.

[0617] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 6:2 and a purity of 99.79%. The anode product is manganese dioxide with a purity of 94.31%. The electrolyzed slurry (i.e., the slurry after electrolysis) is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. The lithium-containing filtrate is evaporated and concentrated, then centrifuged and dried to obtain lithium sulfate crystals with a purity of 99.87%.

[0618] In this embodiment, it can be seen from the overall reaction that the overall system consumes H2SO4, which acts as a sulfur source and H2O2 as a reducing agent. The S in H2SO4 and Li in the cathode powder are matched in a 1:2 molar ratio to form Li2SO4, that is, only S that combines with Li is needed, and S that combines with Co or Ni is not needed, thus reducing the amount of S used. After sufficient electrolysis by feeding, electrolysis is stopped when the lithium sulfate concentration is close to saturation, and the corresponding sulfuric acid also tends to be exhausted. Then, evaporation, concentration, centrifugation and drying are performed to obtain high-purity Li2SO4 crystals.

[0619] Comparative Example 3-1

[0620] (1) Disassemble the waste ternary 622 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 650℃ by introducing air to remove residual conductive agent and binder. The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0621] (2) 300g of positive electrode powder was added to 400g of sulfuric acid solution (mass concentration 98%). At the same time, the volume of the slurry was adjusted to 3L with pure water at T1=50℃ to form a slurry. The dissolution reaction time was t1=1h. The pH of the obtained slurry was 2 and the solid content was W1=0.1g / L.

[0622] (3) Using stainless steel as the cathode plate and lead-calcium alloy as the anode plate, the slurry was electrolyzed at T2 = 60℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 15mA / cm². 2 .

[0623] After about 15 minutes of electrolysis, the pH of the slurry dropped to 1, and obvious bubbles were generated on the cathode plate. This was because there was too little positive electrode powder in the slurry, which could not neutralize the acid produced by electrolysis, thus preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0624] Li in the slurry during electrolysis + The concentration can be continuously increased, and electrolysis can be stopped when the total concentration of nickel and cobalt ions in the electrolyzed slurry is less than 0.05 wt%, as in Example 3-1; or the concentration of Li in the slurry can be increased. + / Na + Electrolysis is stopped when the corresponding salt approaches or reaches saturation concentration, as in Examples 3-2, 3-3, and 3-5; alternatively, the current density of the slurry electrolysis can be below 8 mA / cm². 2 Electrolysis is stopped at certain times, as in Examples 3-4. The electrolyzed slurry is then treated by evaporation concentration or carbonization deposition to obtain high-purity Li₂SO₄ or Li₂CO₃. This achieves the recovery of Li, Na, Co, Ni, and Mn elements, and the recovered products have high purity. In Comparative Example 3-1, however, during electrolysis, the insufficient amount of positive electrode powder in the slurry fails to neutralize the acid generated during electrolysis, leading to the production of hydrogen gas. This prevents the electrolysis process from proceeding normally, resulting in low-purity products.

[0625] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for recycling the positive electrode of a waste battery, comprising the following steps: (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry, the slurry containing a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone the dissolution reaction; (3) The slurry is subjected to electrolytic treatment, and at least the positive electrode powder and the reducing agent are added to the slurry during the electrolytic treatment process; The electrolytic treatment produces sulfuric acid, which then undergoes a dissolution reaction with the added positive electrode powder and the reducing agent. (4) The electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry. The cathode products include nickel and / or cobalt.

2. The recycling method according to claim 1, wherein, In step (2), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH of the slurry is 2 to 6.5; Preferably, in step (2), the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide; Preferably, the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

3. The recycling method according to claim 1, wherein, In step (3), adding at least the positive electrode powder and the reducing agent to the slurry includes: The positive electrode powder and the reducing agent are added to the slurry; or, the positive electrode powder, the reducing agent, and sulfuric acid are added to the slurry. Preferably, in step (3), the positive electrode powder and the reducing agent are added, or the positive electrode powder, the reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.

5.

4. The recycling method according to claim 1, wherein, Steps (2) and (3) include: (2) The slurry is obtained by mixing at least the positive electrode powder, sulfuric acid, the reducing agent, and water and carrying out a dissolution reaction. The temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide. (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

5. The recycling method according to claim 1, wherein, The positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese. When the mass of nickel and / or cobalt in the cathode product increases by m1, the cathode powder and the reducing agent are added. Where m1 ≤ 0.1m0; Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2); Preferably, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1; The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

6. The recycling method according to claim 1, wherein, The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

7. The recycling method according to claim 1, wherein, The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite. During the electrolysis process, the positive electrode powder, the reducing agent, and sulfuric acid are added. Preferably, sulfuric acid is added when the mass of nickel and / or cobalt in the cathode product increases by m1. Wherein, m1≤0.1m0; more preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2); Preferably, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7. Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7); or, When the reducing agent contains sulfur, the number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9×(0.5N5+0.5N7)≤N8+N6≤1.1×(0.5N5+0.5N7); The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

8. The recycling method according to claim 1, wherein, The waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel manganese cobalt oxide, lithium nickel oxide, and lithium cobalt oxide, or... The waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

9. The recycling method according to claim 1, wherein, Step (2): In the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); or, When the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4); The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

10. The recycling method according to claim 1, wherein, The electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element. The filtrate is then purified to obtain a salt containing the first metal element. Preferably, the filter residue is added to the slurry for further electrolysis. Preferably, the first metal element is selected from sodium or lithium, and the purification process is concentration and crystallization. The filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element. More preferably, the concentrated mother liquor is added to the slurry for further electrolytic treatment. Preferably, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition, wherein the filtrate, after carbonization deposition, yields at least a lithium-containing salt and a deposition mother liquor; more preferably, the deposition mother liquor is added to the slurry for further electrolytic treatment.

11. The recycling method according to claim 1, wherein, In step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. Preferably, in step (3), the anode and cathode in the electrolytic treatment are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode. Preferably, in step (4), the anode product includes manganese dioxide.

12. The recycling method according to claim 1, wherein: In step (1), the waste battery is disassembled to obtain the positive electrode, and the positive electrode is pretreated to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese; In step (2), at least the positive electrode powder, sulfuric acid, reducing agent, and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The reducing agent is selected from hydrogen peroxide, sulfuric acid, sulfuric acid, reducing agent, and liquid phase. One or more of the following: sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite; In step (3), the slurry is subjected to electrolytic treatment, and during the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to the slurry; step (4) further includes the following steps: (4.1) When the preset conditions are met, a portion of the electrolyzed slurry is discharged, and the discharged electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element; wherein, the electrolyzed slurry is an electrolysis slurry; The preset condition is 0.7C2≤C1<C2. Wherein, the concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C1, and the theoretical saturation concentration of the salt corresponding to the first metal element in the electrolyzed slurry is C2. (4.2) The filtrate containing the first metal element is purified to obtain salt and mother liquor containing the first metal element. The mother liquor is returned to the slurry in step (3) for further electrolysis.

13. The recycling method according to claim 12, wherein, When the preset conditions are met, the volume of the slurry discharged from the electrolysis is V1, and the volume of the mother liquor returned to step (3) is V2, where 0.95V1≤V2<V1; Preferably, the volume of the slurry in step (2) is V3, where V1 ≤ 0.2V3.

14. The recycling method according to claim 12, wherein, In step (2), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH of the slurry is 2 to 6.5; Preferably, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

15. The recycling method according to claim 12, wherein, In step (3), at least the positive electrode powder and the reducing agent are added to the slurry, including: The positive electrode powder and the reducing agent are added to the slurry; or, the positive electrode powder, the reducing agent, and sulfuric acid are added to the slurry. Preferably, the positive electrode powder and the reducing agent are added, or the positive electrode powder, the reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH of the slurry is maintained in the range of 2 to 6.

5.

16. The recycling method according to claim 12, comprising the following steps: Steps (2) and (3) include: A slurry is obtained by mixing at least the aforementioned positive electrode powder, sulfuric acid, reducing agent, and water and then dissolving them. The slurry contains a solid phase and a liquid phase, wherein the solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The dissolution temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the mixed slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

17. The recycling method according to claim 12, wherein, In step (3), when the mass of nickel and / or cobalt in the cathode product increases by m1 during the electrolysis process, the cathode powder and the reducing agent are added. Wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2); Preferably, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1; The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

18. The recycling method according to claim 12, wherein, The reducing agent is sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

19. The recycling method according to claim 12, wherein, The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The positive electrode powder, the reducing agent, and sulfuric acid are added during the electrolysis process.

20. The recycling method according to claim 19, wherein, When the mass of nickel and / or cobalt added to the cathode product during the electrolysis process is m1, sulfuric acid is added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2); Preferably, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7. Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7); or, When the reducing agent contains sulfur, the number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7); The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

21. The recycling method according to claim 12, wherein, The waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel manganese cobalt oxide, lithium nickel oxide, and lithium cobalt oxide; or... The waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

22. The recycling method according to claim 12, wherein, Step (2): In the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); or, When the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 + P5 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

23. The recycling method according to claim 12, wherein, The first metal element is selected as sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and salt containing the first metal element; The concentrated mother liquor is returned to the slurry in step (3) for further electrolysis.

24. The recycling method according to claim 12, wherein, The first metal element is lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate is then carbonized to obtain a lithium-containing salt, a nickel-containing and / or cobalt-containing salt, and a mother liquor. The salt containing nickel and / or cobalt and the mother liquor of deposition are returned to the slurry in step (3) for further electrolytic treatment; preferably, the mother liquor of deposition is subjected to sodium removal treatment and then returned to the slurry in step (3) for further electrolytic treatment.

25. The recycling method according to claim 12, wherein, The mother liquor is evaporated and concentrated before being added to the slurry in step (3) for further electrolysis, and / or water is added to the slurry during electrolysis.

26. The recycling method according to claim 12, wherein, In step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. Preferably, in step (3), the anode and cathode in the electrolytic treatment are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

27. The recycling method according to claim 12, wherein, The electrolysis process continues without interruption.

28. The recycling method according to claim 1, wherein: In step (1), the waste battery is disassembled to obtain the positive electrode, and the positive electrode is pretreated to obtain positive electrode powder; the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese; In step (2), at least the positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone a dissolution reaction. The reducing agent is selected from one or more of hydrogen peroxide, sulfur dioxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite; In step (3), the slurry is subjected to electrolytic treatment, during which the positive electrode powder and the reducing agent are added to the slurry. Step (4) also includes the following steps: (4.3) When the preset conditions are met, the electrolysis process is stopped to obtain the anode product, the cathode product and the electrolyzed slurry; The cathode product includes nickel and / or cobalt, and the electrolytically treated slurry is the slurry after the electrolysis is completed; Wherein, the reducing agent is selected from sulfur dioxide, and the preset condition is: during the electrolysis process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation; or... The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the preset condition is any one of the following: (a) During the electrolytic treatment process, the ion concentration of the second metal element in the slurry is less than or equal to 0.05 wt%; (b) During the electrolytic treatment, the current density is less than or equal to 8 mA / cm². 2 ; (c) During the electrolytic treatment process, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation.

29. The recycling method according to claim 28, wherein, In step (2), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH of the slurry is 2 to 6.5; Preferably, in step (2), the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

30. The recycling method according to claim 28, wherein, Step (2) includes: A slurry is prepared by mixing at least the aforementioned positive electrode powder, sulfuric acid, reducing agent, and water and reacting them to obtain a slurry containing a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction. The temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

31. The recycling method according to claim 28, wherein, In step (3), the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 2 to 6.

5.

32. The recycling method according to claim 28, wherein, In step (3), when the mass of nickel and / or cobalt in the cathode product increases by m1, the cathode powder and the reducing agent are added. Wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2); Preferably, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1; The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

33. The recycling method according to claim 28, wherein, The waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel manganese cobalt oxide, lithium nickel oxide, and lithium cobalt oxide; or... The waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

34. The recycling method according to claim 28, wherein, Step (2): In the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. When the reducing agent does not contain sulfur, the following condition holds: 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); or, When the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, which satisfies 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 + P5 ≤ 1.1 × (0.5P1 + P2 + 0.5P4). The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

35. The recycling method according to claim 28, wherein, After the electrolysis is completed, the slurry is filtered to obtain filter residue and filtrate containing the first metal element. The filtrate is purified to obtain salt containing the first metal element. Preferably, the filter residue is added to the next slurry for further electrolysis. Preferably, the first metal element is sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element; more preferably, the concentrated mother liquor is added to the next slurry for further electrolytic treatment. Preferably, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate is carbonized to obtain a lithium-containing salt and a mother liquor. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. More preferably, the mother liquor is added to the next slurry for further electrolytic treatment.

36. The recycling method according to claim 28, wherein, In step (4.3), the anode product includes manganese dioxide.

37. The recycling method according to claim 28, wherein, In the preset conditions, the concentration of the salt corresponding to the first metal element in the slurry reaches saturation, satisfying the condition 0.95n≤m≤n; Wherein, the theoretical saturation concentration of the salt corresponding to the first metallic element in the slurry is n. The actual concentration of the salt corresponding to the first metallic element in the slurry is m.

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