Method for recovering positive electrode from spent battery

Abstract

In the recovery method provided by the present application, although sulfuric acid is consumed during the dissolution reaction, an equal amount of sulfuric acid is further generated during the electrolytic treatment, and no additional sulfuric acid needs to be added throughout the entire recovery process, such that the consumption of sulfuric acid is reduced, and the dissolution reaction and the electrolytic reaction can proceed sustainably. Therefore, the recovery method provided in the present application exhibits high recovery rates of nickel and cobalt, small sulfuric acid consumption, and high economic benefits of recovery.

Description

A method for recycling the positive electrode of a waste battery

[0001] This application claims priority to Chinese Patent Application No. 2024118214329, filed on December 11, 2024, entitled "A Method for Recycling the Positive Electrode of a Waste Battery"; Chinese Patent Application No. 2024118212499, filed on December 11, 2024, entitled "A Method for Recycling the Positive Electrode of a Waste Battery"; and Chinese Patent Application No. 2024118216057, filed on December 11, 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. Among these, batteries using ternary materials as the positive electrode active material are particularly widely used.

[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, its recovery efficiency and product quality are relatively low, and it easily generates harmful gases that pollute the environment. Hydrometallurgy, on the other hand, involves pre-treating the cathode material and then using processes such as acid leaching and extraction to enrich and recycle or utilize the valuable metals. However, this process requires large amounts of acids, alkalis, or extraction solutions. Summary of the Invention

[0005] The purpose of this application is to provide a method for recycling the positive electrode of waste batteries, thereby improving the recovery rate of nickel and cobalt while reducing the use of sulfuric acid. The specific technical solution is as follows:

[0006] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0007] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0008] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate.

[0009] The solid filter media includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0010] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0011] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0012] In some embodiments of this application, the recycling method includes the following steps:

[0013] (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder;

[0014] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; wherein the reducing agent is carbon monoxide obtained by heating a mixture of oxalic acid and concentrated sulfuric acid.

[0015] The solid filter media comprises elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0016] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0017] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0018] In some embodiments of this application, the anode product includes either manganese dioxide or oxygen.

[0019] In some embodiments of this application, in step (2), the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min.

[0020] In some embodiments of this application, in step (2), the heat treatment time t1 is 1h to 3h.

[0021] In some embodiments of this application, in step (2), the water washing satisfies at least one of the following conditions:

[0022] Condition a: The solid-liquid ratio for water washing is 1:(10 to 100);

[0023] Condition b: The washing process is completed when the pH of the washing solution after rinsing is 7 to 8.

[0024] In some embodiments of this application, in step (2), the positive electrode powder and oxalic acid are mixed first and then the prepared carbon monoxide is introduced, wherein the mass ratio of the positive electrode powder to oxalic acid is (5 to 10):1.

[0025] In some embodiments of this application, in step (2), the lithium ion elution recovery rate of the lithium-containing filtrate is 95% to 99%.

[0026] In some embodiments of this application, in step (3), the slurry has a solid content W of 1 g / L to 50 g / L and a pH of 3 to 6.5.

[0027] In this application, both the dissolution and subsequent electrolysis processes need to maintain a certain solid content. This is because if all the solid filter material is acid-dissolved, an excess of sulfuric acid is required. However, an excess of sulfuric acid will affect the pH of the electrolysis (which is usually less than 3), making electrolysis impossible or unsustainable.

[0028] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h.

[0029] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, where 0.9N2≤N1≤1.1N2.

[0030] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0031] In some embodiments of this application, in step (4), the solid filter material is added to the slurry during the electrolysis process.

[0032] In some embodiments of this application, the solid filter media is added to the slurry 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 3 to 5.

[0033] In some embodiments of this application, the solid filter material is added when the mass of nickel and / or cobalt in the cathode product increases by m1.

[0034] Where m1 ≤ 0.1m0;

[0035] Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0;

[0036] m0 is the mass of nickel and / or cobalt in the solid filter media in step (3).

[0037] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

[0038] In some embodiments of this application, in step (4), the solid filter material is continuously added to the slurry to ensure that the electrolysis treatment continues without stopping; or,

[0039] The solid filter material is added to the slurry. After a period of time, the feeding is stopped. When the preset conditions are met, the electrolysis process is stopped.

[0040] In some embodiments of this application, the step of stopping the electrolysis process when a preset condition is met is any one of the following conditions:

[0041] (1) The pH of the electrolyzed slurry is less than or equal to 3;

[0042] (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%.

[0043] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0044] In some embodiments of this application, in step (4), 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.

[0045] In the recovery method provided in this application, CO is produced by the reaction of oxalic acid and concentrated sulfuric acid. This provides an acidic atmosphere for the reaction between the cathode powder and CO, allowing some of the cathode powder (LiMeO2) to become molten, transforming the solid-gas two-phase system into a solid-gas-liquid three-phase system. This is beneficial for improving the recovery rate of Li ions in LiMeO2 (Li ions in solution). +The elution recovery rate reaches approximately 95%–99%. Furthermore, CO is used for pre-extraction of lithium, resulting in a very low lithium-ion concentration during subsequent electrolysis. Therefore, Li ions have virtually no impact on the electrolysis process, allowing for continuous electrolysis. In this application, the electrolysis process can be continuous through feeding (of course, this process can be continuous without stopping, or feeding can be stopped when preset conditions are met; those skilled in the art can choose according to the teachings of this application), and the resulting nickel-cobalt alloy has high purity. Additionally, although sulfuric acid is consumed during the dissolution reaction, an equal amount of sulfuric acid is generated during the electrolysis process. No additional sulfuric acid needs to be added during the entire recovery process, reducing sulfuric acid consumption and allowing the dissolution and electrolysis reactions to continue continuously. Therefore, the recovery method provided in this application achieves high nickel-cobalt recovery rates and low sulfuric acid consumption, resulting in high economic benefits. Of course, implementing any product or method of this application does not necessarily require achieving all the advantages described above simultaneously.

[0046] In some embodiments of this application, the recycling method includes the following steps:

[0047] (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder;

[0048] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder; the solid filter material includes elemental Me, oxide MeO and Li2CO3, wherein Me is selected from at least one of elements Ni, Co and Mn;

[0049] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction.

[0050] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0051] In some embodiments of this application, in step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of the positive electrode powder to the carbon powder is 100:(8 to 15).

[0052] In some embodiments of this application, in step (2), the heat treatment time t1 is 1h to 3h.

[0053] In some embodiments of this application, in step (2), the water washing satisfies at least one of the following conditions:

[0054] Condition a: The solid-liquid ratio of the water wash is 1:(10 to 100), wherein the unit of solid in the water wash is g and the unit of liquid is ml;

[0055] Condition b: The washing process is completed when the pH of the washing solution after rinsing is 7 to 8.

[0056] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%.

[0057] In some embodiments of this application, in step (3), the slurry has a solid content W1 of 1 g / L to 50 g / L and a pH of 3 to 6.5.

[0058] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h.

[0059] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9╳(N2+0.5N7)≤N1≤1.1╳(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0060] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0061] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0062] In some embodiments of this application, in step (4), at least the solid filter material is added to the slurry during the electrolysis process.

[0063] In some embodiments of this application, the solid filter media is added to the slurry 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 3 to 6.5.

[0064] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry 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 3 to 6.5.

[0065] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry 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 3 to 5.

[0066] In some embodiments of this application, when the total mass of nickel and / or cobalt added to the cathode product is m1, the solid filter material is added, or the solid filter material and sulfuric acid are added; wherein, m1≤0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter material added when preparing the slurry in step (3).

[0067] In some embodiments of this application, 0.0001m0 ≤ m1 ≤ 0.1m0.

[0068] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

[0069] In some embodiments of this application, the number of moles of lithium in the added solid filter material is N5, and the number of moles of added sulfuric acid is N6, where 0.45N5≤N6≤0.55N5, and the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0070] In some embodiments of this application, step (4) includes any of the following:

[0071] Method 1: Continuously add the solid filter material and sulfuric acid to the slurry. When the first preset condition is reached, discharge part of the electrolytically treated slurry and purify the lithium element in the electrolytically treated slurry to obtain mother liquor. Return the mother liquor to the slurry in step (4) to continue the electrolytic treatment, so that the electrolytic treatment continues without stopping.

[0072] Method 2: Add the solid filter material and sulfuric acid to the slurry, and stop the electrolysis process when the second preset condition is reached;

[0073] Method 3: Add the solid filter material and sulfuric acid to the slurry. After a period of time, stop feeding. Stop the electrolysis process when the third preset condition is reached.

[0074] Method 4: Add the solid filter material to the slurry, and stop the electrolysis process when the fourth preset condition is reached.

[0075] In some embodiments of this application, in Method 1, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

[0076] In some embodiments of this application, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V.

[0077] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) to continue the electrolytic treatment. The purification treatment includes evaporation, concentration and crystallization or carbonization deposition.

[0078] In some embodiments of this application, in the second method, the second preset condition is the actual concentration C1 of lithium salt in the electrolyzed slurry, which satisfies 0.9C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

[0079] In some embodiments of this application, in method three, the third preset condition is any one of the following conditions:

[0080] (1) The pH of the electrolyzed slurry is less than or equal to 3;

[0081] (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%;

[0082] (3) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

[0083] In some embodiments of this application, in method four, the fourth preset condition is any one of the following conditions:

[0084] (4) The pH of the electrolyzed slurry is greater than or equal to 6.5;

[0085] (5) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%;

[0086] (6) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

[0087] The recycling method provided in this application pre-recovers lithium from waste ternary lithium batteries, achieving the separation of lithium and nickel, cobalt, and manganese. Specifically, the cathode powder is heat-treated with a reducing agent to reduce the nickel, cobalt, and manganese, and then washed with water to essentially separate the nickel, cobalt, and manganese from the lithium. The resulting solid filter material mainly consists of nickel, cobalt, and manganese metal (Me) and its oxide (MeO), and also includes a small amount of Li2CO3. Subsequently, the nickel, cobalt, and manganese metal and its oxide produced by reduction are acid-dissolved and electrolyzed. During the slurry electrolysis process, the washed solid filter material and a small amount of sulfuric acid can be continuously added, and part of the electrolyzed slurry (i.e., the slurry in electrolysis) can be discharged. After lithium extraction, the resulting mother liquor can be returned, thus achieving a cyclical recycling process. Alternatively, the washed solid filter material and a small amount of sulfuric acid can be added, and the electrolysis process can be stopped when preset conditions are reached. Alternatively, the feeding can be stopped after electrolysis for a period of time as needed, that is, the addition of washed solid filter material and sulfuric acid can be stopped, and the electrolysis process will stop. Alternatively, only solid filter material can be added, and the electrolysis process can be stopped when preset conditions are reached. In the four processes described above, sulfuric acid is generated during electrolysis, and only Li+ ions consume sulfuric acid, significantly reducing sulfuric acid consumption compared to traditional processes, and the processing flow is also simple. Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above simultaneously.

[0088] In some embodiments of this application, the recycling method includes the following steps:

[0089] (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder;

[0090] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then acid-washed and filtered to obtain solid filter material and lithium-containing filtrate; the molar ratio of lithium element in the positive electrode powder to hydrogen element in the acid used in the acid washing is 1:(1.3 to 2).

[0091] The solid filter media comprises elemental Me and oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0092] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction.

[0093] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0094] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0095] In some embodiments of this application, the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of the positive electrode powder to the carbon powder is 100:(8 to 15).

[0096] In some embodiments of this application, in step (2), the heat treatment time t1 is 1h to 3h.

[0097] In some embodiments of this application, in step (2), the acid is selected from sulfuric acid.

[0098] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 95% to 99%.

[0099] In some embodiments of this application, in step (3), the slurry has a solid content W1 of 1 g / L to 50 g / L and a pH of 3 to 6.5.

[0100] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h.

[0101] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, satisfying 0.9N2≤N1≤1.1N2.

[0102] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0103] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0104] In some embodiments of this application, in step (4), the solid filter material is added to the slurry during the electrolysis process.

[0105] In some embodiments of this application, the solid filter media is added to the slurry 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 3 to 6.5.

[0106] In some embodiments of this application, the solid filter media is added to the slurry 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 3 to 5.

[0107] In some embodiments of this application, when the total mass of nickel and / or cobalt in the cathode product increases by m1, the solid filter material is added; wherein, m1≤0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter material added when preparing the slurry in step (3).

[0108] In some embodiments of this application, 0.0001m0 ≤ m1 ≤ 0.1m0.

[0109] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

[0110] In some embodiments of this application, in step (4), the solid filter material is continuously added to the slurry so that the electrolysis process continues without stopping; or, the solid filter material is added to the slurry, and after a period of time, the feeding is stopped, and the electrolysis process is stopped when the preset conditions are met.

[0111] In some embodiments of this application, the step of stopping the electrolysis process when a preset condition is met is any one of the following conditions:

[0112] (1) The pH of the electrolyzed slurry is less than or equal to 3;

[0113] (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%.

[0114] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0115] In some embodiments of this application, in step (4), 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.

[0116] In some embodiments of this application, in step (4), the anode product includes either manganese dioxide or oxygen.

[0117] In the recycling method provided in this application, the cathode powder and reducing agent are heat-treated to remove carbon from the cathode powder and reduce the nickel, cobalt, and manganese. Then, most of the lithium and nickel, cobalt, and manganese are separated by acid washing, resulting in solid filter media mainly composed of nickel, cobalt, and manganese metal (Me) and its oxide (MeO). The solid filter media containing Me and MeO is then dissolved and electrolyzed using sulfuric acid. Furthermore, in this application, the electrolysis process can be continuous by replenishing the feed. This can be achieved by continuously replenishing the acid-washed solid filter media during slurry electrolysis, thus realizing a cyclical recycling process (continuous electrolysis without interruption); or by stopping the feed after a period of electrolysis as needed, i.e., stopping the replenishment of acid-washed solid filter media, which stops the electrolysis. The nickel-cobalt alloy obtained by electrolysis in this process has high purity. In both of these processes, sulfuric acid is generated during electrolysis, and this sulfuric acid is used to further dissolve the replenished solid filter media. There is little or no sulfuric acid consumption, and no additional sulfuric acid needs to be added during the entire recycling process. Compared with traditional processes, this significantly reduces sulfuric acid consumption, and the processing flow is simple. 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

[0118] 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.

[0119] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0120] Figure 1 shows the XRD pattern of the solid filter media in Example 1-1;

[0121] Figure 2 is an experimental flowchart of Example 1-1.

[0122] Figure 3 is a flowchart of the recycling methods of some embodiments of this application;

[0123] Figure 4 shows the X-ray diffraction pattern of the calcined material in Example 2-1.

[0124] Figure 5 shows the XRD pattern of the material after reduction and calcination in Example 3-1;

[0125] Figure 6 is an experimental flowchart of Example 3-1. Detailed Implementation

[0126] 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.

[0127] Currently, there are several methods for recycling ternary cathode materials from spent batteries. One method involves adding carbon to the spent ternary cathode material, continuously introducing CO2 during roasting, and then carbonizing it during water leaching. This converts Li to Li₂CO₃, separating it from other elements. Other elements such as nickel, cobalt, and manganese are then separated and extracted using acid leaching followed by extraction. This process requires the addition of additional carbon source, and the subsequent separation of nickel, cobalt, and manganese consumes acid and alkali, resulting in significant resource consumption. Another method involves reducing the ternary cathode material powder by introducing one or more of carbon monoxide, nitrogen, and natural gas during roasting. After water leaching to obtain a lithium-rich solution, resin purification is performed, followed by the introduction of carbon dioxide. The remaining residue is then acid-dissolved, precipitated, and extracted for recovery. This method requires two steps for lithium extraction, and nickel, cobalt, and manganese require additional acid-alkali treatment and extraction, also resulting in high resource consumption.

[0128] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0129] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0130] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate; the solid filter material includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co and Mn;

[0131] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0132] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0133] In some embodiments of this application, in step (2), the reducing agent is carbon monoxide obtained by heating a mixture of oxalic acid and concentrated sulfuric acid.

[0134] In some embodiments of this application, in step (2), the washing is a water wash.

[0135] This application also provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0136] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0137] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; wherein, the reducing agent is carbon monoxide obtained by heating a mixture of oxalic acid and concentrated sulfuric acid; the solid filter material includes elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co and Mn;

[0138] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0139] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0140] In this application, the positive electrode refers to a positive electrode whose active material is mainly LiMeO2, wherein Me is selected from at least one of the elements Ni, Co, and Mn. For example, the positive electrode of a ternary lithium battery or a lithium cobalt oxide battery.

[0141] The recovery method provided in this application prepares CO using a combination of oxalic acid and concentrated sulfuric acid. The resulting CO is used to remove carbon from the cathode powder. Specifically, CO reacts with LiMeO2 to generate CO2, which then reacts with C in the cathode powder to produce CO. This CO2 continues to react with the cathode powder, removing carbon and reducing nickel, cobalt, and manganese. After washing with water, nickel, cobalt, manganese, and lithium in the cathode powder are separated, resulting in a solid filter material that is essentially carbon-free. The resulting solid filter material, containing nickel, cobalt, and manganese metals (Me) and their oxides (MeO), is then dissolved and electrolyzed using sulfuric acid. During the slurry electrolysis process, the washed solid filter material can be continuously replenished, thus achieving a cyclical recovery process. Alternatively, the feeding can be stopped after a period of electrolysis, meaning the replenishment of washed solid filter material ceases, and the electrolysis stops. In both processes, since an equal amount of sulfuric acid is generated during electrolysis, no additional sulfuric acid is consumed, avoiding significant sulfuric acid consumption.

[0142] Specifically, in the recovery method provided in this application, the dissolution and electrolysis processes of the solid filter media Me / MeO are carried out in the same electrolytic cell or connected containers. Since sulfuric acid is generated during the electrolysis process, the H2SO4 produced can continuously dissolve the newly added solid filter media Me / MeO, allowing for full utilization of the sulfuric acid and reducing acid consumption. In this process, the amount of sulfuric acid used is significantly reduced compared to traditional processes, which often require SO4 in combination with Co, Ni, and Mn. 2- If calculated using sulfur (S), 1 mol of Co / Ni / Mn corresponds to 1 mol of S, thus requiring a corresponding amount of S to match the molar amounts of Co, Ni, and Mn. However, in the recovery method provided in this application, Li is almost completely removed during the water washing step, and the sulfuric acid consumed by Me / MeO during dissolution corresponds to (equal in amount to) the H2SO4 produced during electrolysis. Therefore, no additional S is needed, thus reducing the consumption of sulfuric acid. Consequently, the overall demand for sulfuric acid or acidic substances is reduced during the recovery process.

[0143] In addition, the CO produced by the reaction of oxalic acid and concentrated sulfuric acid provides an acidic atmosphere for step (2), allowing some LiMeO2 to become molten, transforming the solid-gas two-phase into a solid-gas-liquid three-phase system. This is beneficial for improving the recovery rate of Li ions in LiMeO2. Furthermore, due to the high recovery rate of Li ions, the subsequent slurry electrolysis process is relatively simple, meaning that the influence of Li ions on electrolysis is basically unnecessary. Electrolysis can be carried out continuously without any other processing steps, simplifying the recovery process. Meanwhile, in step (2), the heat treatment temperature T1 is between 550°C and 700°C. For example, the heat treatment temperature T1 can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, or 700°C, or any two of the above values. If the heat treatment temperature is too low, the structure of LiMeO2 cannot be destroyed, the reaction is incomplete, and most of the trivalent Me ions cannot be converted into divalent Me ions. If the heat treatment temperature is too high, most of the Li will volatilize, resulting in a significant decrease in Li recovery rate and economic losses. Therefore, by controlling the heat treatment temperature T1 within the above-mentioned range, CO can react fully with LiMeO2, resulting in a higher lithium recovery rate and thus improving the economic efficiency of the recycling process.

[0144] This application does not impose any particular restrictions on the method of obtaining the positive electrode of the waste battery, as long as it can achieve the purpose of this application. For example, it can be obtained by dismantling the waste battery or by purchasing it directly.

[0145] In this application, the reaction equation for oxalic acid and concentrated sulfuric acid in step (2) is as follows:

[0146] In this application, the heat treatment in step (2) includes the following reactions: 2CO + 2LiMeO2 = Li2CO3 + Me + MeO + CO2↑; CO2 + C = 2CO↑.

[0147] In this application, the dissolution reaction in step (3) includes the following reactions: Me + H2SO4 = H2↑ + MeSO4; MeO + H2SO4 = H2O + MeSO4.

[0148] In this application, when Me is selected from Ni, Co, and Mn (i.e., the waste battery is a nickel-cobalt-manganese ternary battery), the electrolytic treatment in step (4) includes the following reactions: 2NiSO4+2H2O=2Ni+2H2SO4+O2↑ 2CoSO4+2H2O=2Co+2H2SO4+O2↑ NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4 CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0149] In one possible example, for an 811 ternary battery, after reduction and calcination of the solid filter material, Ni and Co elements mainly exist in elemental state, while Mn element mainly exists in oxide MnO state:

[0150] The dissolution reactions include: 8Ni + Co + MnO + 10H₂SO₄ = 8NiSO₄ + CoSO₄ + MnSO₄ + H₂O + 9H₂↑

[0151] The electrolysis reaction is: 8NiSO4 + CoSO4 + MnSO4 + 10H2O = 8Ni + Co + MnO2 + 10H2SO4 + 4O2↑;

[0152] Therefore, the overall reaction formula for dissolution and electrolysis includes the reaction shown in the following formula, in which elemental Ni and Co are transformed from the slurry into cathode products: 8Ni+Co+MnO+9H2O=8Ni+Co+MnO2+9H2↑+4O2↑.

[0153] As can be seen from the above reaction formula, although sulfuric acid is consumed in the dissolution reaction, an equal amount of sulfuric acid is generated in the electrolysis process. Therefore, no additional sulfuric acid needs to be added in the entire recovery process, which reduces the amount of sulfuric acid consumed.

[0154] Other ternary batteries are similar, such as the ternary 622 lithium-ion battery and the ternary 523 lithium-ion battery, which will not be discussed further here.

[0155] In another possible example, for lithium cobalt oxide batteries, the solid filter material consists of elemental Co and oxide CoO, and the total reaction anode produces O2 without consuming sulfuric acid;

[0156] Specifically, when Me is Co (i.e., the waste battery is a lithium cobalt oxide battery), the electrolytic treatment in step (4) includes the following reaction: 2CoSO4+2H2O=2Co+2H2SO4+O2↑;

[0157] The overall reaction equations are: 2CoO=2Co+O2↑; 2Co+2H2O=2Co+2H2↑+O2↑

[0158] In some embodiments of this application, the waste battery is a waste ternary nickel-cobalt-manganese battery, and the anode product includes manganese dioxide.

[0159] In some embodiments of this application, in step (2), the mass of oxalic acid is Z g, the volume of concentrated sulfuric acid is P mL, Z:P = (5 to 50):1; the heating temperature T5 after mixing oxalic acid and concentrated sulfuric acid is 150°C to 250°C.

[0160] In some embodiments of this application, in step (2), the flow rate V of carbon monoxide introduced per 10g of cathode powder is 1L / min to 3L / min. For example, the flow rate V of carbon monoxide can be 1L / min, 1.2L / min, 1.4L / min, 1.5L / min, 1.6L / min, 1.8L / min, 2L / min, 2.2L / min, 2.4L / min, 2.5L / min, 2.6L / min, 2.8L / min, or 3L / min, or any two of the above values. By controlling the flow rate V of carbon monoxide within the above range, on the one hand, CO reacts fully with LiMeO2, which is beneficial for separating lithium elements during the subsequent water washing process; on the other hand, residual carbon in the cathode powder can be removed. The resulting solid filter material is essentially free of lithium elements and carbon, which is beneficial for improving the recovery rate of Me elements.

[0161] In some embodiments of this application, the heat treatment time t1 in step (2) is between 1 h and 3 h. For example, the heat treatment time t1 can be 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, or 3 h, or any two of the above values. By adjusting the heat treatment time t1 within the above range, CO can fully react with LiMeO2, converting trivalent Me ions into divalent Me ions, which is beneficial to improving the recovery rate of Me element; moreover, lithium element is not easily volatilized, and the recovery rate of lithium element is high when recovering lithium element through lithium-containing filtrate in the subsequent process. Thus, the economic benefits of the recovery process can be improved.

[0162] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100). For example, the solid-liquid ratio X can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100, or any two of the above numbers. By adjusting the solid-liquid ratio X of the water washing within the above range, the recovery rate of lithium ions can be improved.

[0163] In some embodiments of this application, in step (2), the washing is completed when the pH of the washing solution after multiple washes is 7 to 8. For example, the pH of the washing solution can be 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8, or any two of the above numbers. If the pH of the washing solution after washing is within the above range, it indicates that the lithium element is basically cleaned. Therefore, by controlling the pH of the washing solution within the above range, effective separation of lithium and Me elements can be achieved.

[0164] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100), and the pH of the washing solution after water washing is 7 to 8, at which point the water washing is completed. By adjusting the solid-liquid ratio X of the water washing and the pH of the washing solution after water washing within the above ranges, effective separation of lithium and Me elements can be achieved.

[0165] In some embodiments of this application, in step (2), the cathode powder and oxalic acid are mixed first, and then the prepared carbon monoxide is introduced. The mass ratio Y of the cathode powder to oxalic acid is (5 to 10):1. For example, the mass ratio Y can be 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1, or any two of the above numbers. Mixing the cathode powder and oxalic acid can produce CO, CO2, and H2O. First, the generated CO is beneficial for a more complete reaction between the cathode powder and CO. Second, the generated CO2 reacts with the C in the cathode powder to generate more CO, which is more beneficial for a complete reaction between the cathode powder and CO. Third, the generated H2O can adjust the reaction atmosphere, which is beneficial for the reaction between the cathode powder and CO to proceed in a solid-gas-liquid three-phase state. Furthermore, the early addition of oxalic acid ensures a sufficient CO supply and the presence of H2O to adjust the atmosphere, which facilitates the reaction between CO and the cathode powder, shortens the reaction time, and particularly improves the elution recovery rate of Li ions (reaching over 98%). This allows for simpler and more sustainable subsequent slurry electrolysis and more thorough reduction of metals such as Ni and Co. By controlling the mass ratio Y of cathode powder to oxalic acid within the aforementioned range, it is beneficial for the cathode powder to react fully with CO, thereby improving the recovery rates of nickel, cobalt, and lithium.

[0166] In some embodiments of this application, in step (3), the solid content W of the slurry is from 1 g / L to 50 g / L, and the pH is from 3 to 6.5. For example, the solid content W 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 figures. For example, the pH of the slurry can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. By controlling the solid content W1 and pH of the slurry in step (3) within the above ranges, it is possible to avoid the continuous generation of sulfuric acid and the resulting H+ during subsequent electrolysis treatment due to the electrolysis rate exceeding the dissolution rate. + Accumulation can lead to problems that affect subsequent electrolytic treatment. During the initial preparation of the slurry, maintaining a pH of 3–6.5 is beneficial for the smooth initiation of the electrolysis process.

[0167] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C, and the time t2 is 0.5h to 2h. For example, the temperature T2 of the dissolution reaction can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the time t2 of the dissolution reaction can be 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 T2 and time t2 of the dissolution reaction within the above ranges, it is beneficial for the cathode powder to be fully dissolved to obtain a slurry with the desired solid content.

[0168] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt, and manganese in the liquid phase is N2, where 0.9N2≤N1≤1.1N2. For example, N1 can be 0.90N2, 0.91N2, 0.92N2, 0.93N2, 0.94N2, 0.95N2, 0.96N2, 0.97N2, 0.98N2, 0.99N2, N2, 1.01N2, 1.02N2, 1.03N2, 1.04N2, 1.05N2, 1.06N2, 1.07N2, 1.08N2, 1.09N2, or 1.1N2, or any two of the above numbers. The total number of moles of Me in the liquid phase is basically the same as the number of moles of sulfuric acid. During the dissolution process, Me can be converted into MeSO4, and then sulfuric acid can be generated during the electrolysis process. No additional sulfuric acid needs to be added during the subsequent dissolution and electrolysis processes. That is, only sulfuric acid with the same total number of moles of Me is added during the initial dissolution reaction. No sulfuric acid is consumed in the later electrolysis / dissolution processes. Therefore, the overall consumption of sulfuric acid is low, which improves the economic benefits of the recovery.

[0169] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt, and manganese in the solid filter material is N5, where N1 < N5. For example, N1 can be 0.9N5, 0.85N5, 0.8N5, 0.7N5, 0.6N5, 0.5N5, 0.4N5, 0.3N5, ​​etc. To ensure that the pH of the slurry meets the requirements and to better initiate electrolysis directly, the difference between N1 and N5 can be larger, and the undissolved solid filter material can be dissolved using sulfuric acid generated by electrolysis. For example, 0.4N5 ≤ N1 ≤ 0.8N5.

[0170] In some embodiments of this application, in step (3), the sulfuric acid is commercially available concentrated sulfuric acid.

[0171] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 40°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0172] In some embodiments of this application, in step (4), solid filter media is added to the slurry during the electrolysis process. Preferably, the solid filter media is added to the slurry during the electrolysis process to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH in the range of 3 to 5. The newly added water-washed solid filter media (Me / MeO) to the slurry can, on the one hand, continuously react with the H2SO4 generated by electrolysis to dissolve, that is, consume the H in the system. + Maintaining the pH of the system within the aforementioned range ensures the normal operation of the electrolysis process. Furthermore, the generation of H2SO4 during slurry electrolysis allows for the continued dissolution of newly added solid filter media (Me / MeO), increasing the throughput of solid filter media. The recycling of H2SO4 reduces the overall amount used, enabling the electrolysis reaction to proceed continuously. Additionally, the absence of a reducing agent during electrolysis reduces its usage and saves process steps. Therefore, by adding solid filter media to maintain the slurry's solid content and pH within the aforementioned range, the dissolution and electrolysis reactions can continue (including continuous electrolysis or cessation after a certain period), and the continuous generation of sulfuric acid can prevent the formation of H2SO4. + This accumulation can hinder the normal operation of the electrolytic process.

[0173] In some embodiments of this application, solid filter media is added when the total mass of nickel and / or cobalt in the cathode product increases by m1. Wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter media in step (3). 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, solid filter media is added while the electrolysis reaction is underway, which is beneficial for achieving continuous recovery. For example, m1 = 0.1m0, that is, when the cathode produces a certain amount of product, solid filter material is added.

[0174] In some embodiments of this application, the amount of supplementary solid filter media 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 supplementary solid filter media 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 N3, and the total molar amount of nickel and / or cobalt in the supplementary solid filter media is N4, where 0.95N3 ≤ N4 ≤ 1.05N3. For example, N4 can be 0.95N3, 0.96N3, 0.97N3, 0.98N3, 0.99N3, N3, 1.01N3, 1.02N3, 1.03N3, 1.04N3, or 1.05N3, or any two of the above numbers.

[0175] In some embodiments of this application, in step (4), solid filter media is continuously added to the slurry to keep the electrolysis process running without stopping. During the slurry electrolysis process, H2SO4 is generated, which can continue to dissolve the newly added solid filter media (Me / MeO). The H2SO4 is recycled, thereby allowing the electrolysis reaction and dissolution reaction to continue.

[0176] In some embodiments of this application, in step (4), solid filter material is added to the slurry, and after a period of time, the feeding is stopped. Electrolysis is stopped when preset conditions are met. In this process, those skilled in the art can arbitrarily set preset conditions according to actual needs. Preferably, the preset condition is: the pH of the electrolyzed slurry is less than or equal to 3. For example, the pH of the electrolyzed slurry can be 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.7, 2.9 or 3, or any two of the above numbers. When the pH of the electrolyzed slurry is less than or equal to 3, it indicates that a large amount of sulfuric acid has accumulated during the electrolysis process, affecting the continued progress of the electrolysis reaction. At this time, electrolysis can be stopped. In this application, the above "period of time" can be selected according to actual conditions, and this application does not limit it.

[0177] In some embodiments of this application, in step (4), solid filter media is added to the slurry, and after a period of time, the feeding is stopped. Electrolysis is stopped when a preset condition is reached. Preferably, the preset condition is that the total mass concentration C of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%. For example, the total mass concentration C can be 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.045%, 0.049%, or 0.05%, or between any two of the above values. When the total mass concentration C of nickel ions and / or cobalt ions is less than or equal to 0.05%, it indicates that the Me element has been basically recovered, and electrolysis can be stopped at this time. In this application, the above-mentioned "period of time" can be selected according to the actual situation, and this application does not limit it.

[0178] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T4 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, or 800°C, or any two of the above numbers. For example, the time t4 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 the positive electrode material layer of the obtained 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 have any particular limitation on the particle size of the positive electrode material layer powder, as long as it can achieve the purpose of this application.

[0179] In some embodiments of this application, in step (4), 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.

[0180] In some embodiments of this application, the waste battery is one or more of waste ternary nickel-cobalt-manganese batteries or waste lithium cobalt oxide batteries.

[0181] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0182] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0183] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate; the solid filter material includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co and Mn;

[0184] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0185] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0186] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0187] In some embodiments of this application, in step (2), the washing is a water wash.

[0188] The recycling method provided in this application has a simple processing flow and can reduce the amount of acid used, resulting in low resource consumption.

[0189] The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0190] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0191] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550℃ to 700℃, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder. Specifically, Figure 3 is an experimental flowchart in which the reducing agent is selected from carbon monoxide; the solid filter material includes elemental Me, oxide MeO and Li2CO3, wherein Me is selected from at least one of the elements Ni, Co and Mn.

[0192] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0193] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0194] The recycling method provided in this application pre-recovers lithium from waste ternary lithium batteries, achieving separation of lithium and nickel, cobalt, and manganese. Specifically, when the reducing agent is carbon monoxide (CO), the reaction 2LiMeO2 + 2CO = Li2CO3 + Me + MeO + CO2 occurs. CO reacts with LiMeO2 to generate CO2, which then reacts with C in the cathode powder to generate CO. This CO2 continues to react with the cathode powder, removing carbon and reducing nickel, cobalt, and manganese. The nickel, cobalt, and manganese are then largely separated from lithium through water washing. The resulting solid filter material mainly consists of nickel, cobalt, and manganese metal (Me) and its oxide (MeO), and also includes a small amount of Li2CO3. Subsequently, the reduced nickel, cobalt, and manganese metal and its oxide are acid-dissolved and electrolyzed. During the slurry electrolysis process, the washed solid filter material and a small amount of sulfuric acid can be continuously added to ensure the lithium content in the slurry during electrolysis. + With a suitable Ni content (not too high to cause saturation and affect electrolysis), some of the electrolyzed slurry can be discharged to ensure the Ni content in the slurry during the electrolysis process. 2+ / Co2 + The dynamic equilibrium of lithium content allows the mother liquor obtained after lithium extraction to be returned to the slurry in the electrolysis process, thus achieving a cyclical recycling process. Alternatively, it can be supplemented with washed solid filter media and a small amount of sulfuric acid to achieve the desired Li content in the slurry. + Electrolysis should be stopped when the concentration is saturated or near saturation; alternatively, feeding can be stopped after a period of electrolysis, i.e., the addition of washed solid filter media and sulfuric acid should be stopped, while electrolysis will continue. +The concentration gradually increases while the content of nickel and cobalt ions gradually decreases, and the electrolytic treatment will stop after reaching a certain level; alternatively, only solid filter media can be added. The lithium in the solid filter media will consume the sulfuric acid in the slurry, and the electrolytic treatment will stop when preset conditions are reached. In the above four processes, since sulfuric acid is generated during the electrolytic treatment, the consumption of sulfuric acid is greatly reduced compared with traditional processes, and the treatment process is simple.

[0195] When carbon (C) powder is used as the reducing agent, the reaction 2LiMeO2 + C = Li2CO3 + Me + MeO occurs, removing carbon from the cathode powder and reducing nickel, cobalt, and manganese. The process is similar to when CO is used as the reducing agent, and will not be elaborated further here. When using carbon powder as the reducing agent, an inert gas, such as nitrogen, is introduced to facilitate the reduction roasting process.

[0196] Specifically, in the recovery method provided in this application, the dissolution and electrolysis processes of the solid filter media Me / MeO are carried out in the same electrolytic cell or connected containers. Since sulfuric acid is generated during the electrolysis process, the H2SO4 produced can continuously dissolve the newly added solid filter media Me / MeO, allowing for full utilization of the sulfuric acid and reducing acid consumption. In this process, the amount of sulfuric acid used is significantly reduced compared to traditional processes, which often require SO4 in combination with Co, Ni, and Mn. 2- If calculated using sulfur (S), 1 mol of Co / Ni / Mn corresponds to 1 mol of S, thus requiring a corresponding amount of S to match the molar amounts of Co, Ni, and Mn. However, in the recovery method provided in this application, most of the Li element is removed during the water washing step. The sulfuric acid consumed by Me / MeO during dissolution corresponds to (equal in amount to) the H2SO4 produced during electrolysis, meaning that Me does not consume S. Therefore, only the S element needed to replenish the Li that was not washed away during the water washing process needs to be replenished, thus reducing the consumption of sulfuric acid. Consequently, the overall demand for sulfuric acid or acidic substances is reduced during the recovery process.

[0197] In addition, in step (2), the heat treatment temperature T1 is between 550°C and 700°C. For example, the heat treatment temperature T1 can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, or 700°C, or any two of the above numbers. When the heat treatment temperature is too low, for example below 550°C, the structure of LiMeO2 cannot be destroyed, the reaction is insufficient, and most of the trivalent Me ions cannot be converted into divalent Me ions. When the heat treatment temperature is too high, for example above 700°C, most of the Li element will volatilize, resulting in a significant reduction in the Li recovery rate and causing economic losses. Therefore, by controlling the heat treatment temperature T1 within the above range, the reducing agent can react fully with LiMeO2, the lithium element recovery rate is high, and thus the economic benefits of the recycling process can be improved.

[0198] This application does not impose any particular restrictions on the method of obtaining the positive electrode of the waste battery, as long as it can achieve the purpose of this application. For example, it can be obtained by dismantling the waste battery or by purchasing it directly.

[0199] In this application, when the reducing agent is selected from CO, the heat treatment in step (2) includes the following reactions: 2CO+2LiMeO2=Li2CO3+Me+MeO+CO2↑; CO2+C=2CO↑.

[0200] In this application, the dissolution reaction in step (3) includes the following reactions: Me + H2SO4 = H2↑ + MeSO4; MeO + H2SO4 = H2O + MeSO4; Li2CO3 + H2SO4 = Li2SO4 + H2O + CO2.

[0201] In this application, when Me is selected from Ni, Co, and Mn (i.e., the waste battery is a nickel-cobalt-manganese ternary battery), the electrolytic treatment in step (4) includes the following reactions: 2NiSO4+2H2O=2Ni+2H2SO4+O2↑ 2CoSO4+2H2O=2Co+2H2SO4+O2↑ NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4 CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0202] In one possible example, for an 811 ternary battery, after reduction and calcination of the solid filter material, Ni and Co elements mainly exist in elemental form, Mn element mainly exists in oxide form (MnO), and a small amount of Li₂CO₃ is also contained.

[0203] The dissolution reactions include: 8Ni + Co + MnO + 10H₂SO₄ = 8NiSO₄ + CoSO₄ + MnSO₄ + H₂O + 9H₂↑; Li₂CO₃ + H₂SO₄ = Li₂SO₄ + H₂O + CO₂↑;

[0204] The electrolysis reaction includes: 8NiSO4 + CoSO4 + MnSO4 + 10H2O = 8Ni + Co + MnO2 + 10H2SO4 + 4O2↑;

[0205] Therefore, the overall reaction formula for dissolution and electrolysis includes the following reactions, in which elemental Ni and Co are transformed from the slurry into cathode products: 8Ni+Co+MnO+9H2O=8Ni+Co+MnO2+9H2↑+4O2↑; Li2CO3+H2SO4=Li2SO4+H2O+CO2↑.

[0206] As can be seen from the above reaction formula, although sulfuric acid is consumed during the dissolution reaction of nickel, cobalt, and manganese, an equal amount of sulfuric acid is generated during the electrolysis process. Only lithium carbonate consumes sulfuric acid. Therefore, only the amount of sulfuric acid corresponding to that of lithium carbonate needs to be replenished during the entire recovery process, thus reducing the amount of sulfuric acid consumed. At the same time, since the content of lithium carbonate is relatively small, the amount of sulfuric acid consumed is also small, resulting in a reduction in the total amount of sulfuric acid consumed during the entire recovery process.

[0207] Other ternary batteries are similar, such as the ternary 622 lithium-ion battery and the ternary 523 lithium-ion battery, which will not be discussed further here.

[0208] In another possible example, for lithium cobalt oxide batteries, the solid filter material includes elemental Co, oxide CoO and Li2CO3. The overall reaction anode produces O2, and only Li2CO3 consumes sulfuric acid. However, due to the low content of lithium carbonate, the overall amount of sulfuric acid consumed is also low.

[0209] Specifically, when Me is Co (i.e., the waste battery is a lithium cobalt oxide battery), the dissolution reaction in step (3) includes the following reactions: Co + H2SO4 = H2↑ + CoSO4; CoO + H2SO4 = H2O + CoSO4; Li2CO3 + H2SO4 = Li2SO4 + H2O + CO2↑;

[0210] The electrolytic treatment in step (4) includes the following reaction: 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2↑;

[0211] The overall reaction equations include: 2CoO=2Co+O2↑; 2Co+2H2O=2Co+2H2↑+O2↑; Li2CO3+H2SO4=Li2SO4+H2O+CO2↑;

[0212] In some embodiments of this application, the waste battery is a waste ternary nickel-cobalt-manganese battery, and the anode product includes manganese dioxide.

[0213] In some embodiments of this application, in step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min. For example, the flow rate V of carbon monoxide can be 1L / min, 1.2L / min, 1.4L / min, 1.5L / min, 1.6L / min, 1.8L / min, 2L / min, 2.2L / min, 2.4L / min, 2.5L / min, 2.6L / min, 2.8L / min, or 3L / min, or any two of the above numbers. By adjusting the flow rate V of carbon monoxide within the above range, on the one hand, CO and LiMeO2 react fully, which is beneficial for separating lithium elements in the subsequent water washing process; on the other hand, residual carbon in the positive electrode powder can be removed. The resulting solid filter material is basically free of carbon and most of the lithium elements are washed away, which is beneficial for improving the recovery rate of Me elements.

[0214] In some embodiments of this application, the reducing agent is selected from carbon powder, and the mass ratio of cathode powder to carbon powder is 100:(8 to 15). For example, the mass ratio of cathode powder to carbon powder can be 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, or 100:15, or any two of the above numbers. By adjusting the mass ratio of cathode powder to carbon powder within the above range, the carbon powder reacts fully with LiMeO2, which is beneficial for separating lithium elements during the subsequent acid washing process.

[0215] In some embodiments of this application, the heat treatment time t1 in step (2) is between 1 h and 3 h. For example, the heat treatment time t1 can be 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, or 3 h, or any two of the above values. By adjusting the heat treatment time t1 within the above range, CO can fully react with LiMeO2, converting trivalent Me ions into divalent Me ions, which is beneficial to improving the recovery rate of Me element; moreover, lithium element is not easily volatilized, and the recovery rate of lithium element is high when recovering lithium element through lithium-containing filtrate in the subsequent process. Thus, the economic benefits of the recovery process can be improved.

[0216] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100), in g / ml. For example, the solid-liquid ratio X can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100, or any two of the above numbers. By adjusting the solid-liquid ratio X of the water washing within the above range, the recovery rate of lithium ions can be improved.

[0217] In some embodiments of this application, in step (2), the washing is completed when the pH of the washing solution after multiple washes is 7 to 8. For example, the pH of the washing solution can be 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8, or any two of the above numbers. The fact that the pH of the washing solution after washing is within the above range indicates that most of the lithium element has been cleaned. Therefore, by controlling the pH of the washing solution within the above range, effective separation of lithium and me elements can be achieved.

[0218] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100), and the pH of the washing solution after water washing is 7 to 8, at which point the water washing is completed. By adjusting the solid-liquid ratio X of the water washing and the pH of the washing solution after water washing within the above ranges, effective separation of lithium and Me elements can be achieved.

[0219] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%. For example, the lithium elution rate of the lithium-containing filtrate can be 85%, 86%, 87%, 88%, 89%, or 90%, or any two of the above figures. A lithium elution rate within the above range indicates that after acid washing, most of the lithium element remains in the lithium-containing filtrate, thus increasing the lithium recovery rate during subsequent lithium element recovery from the filtrate. Simultaneously, it can reduce the lithium content in the solid filter material, which is beneficial for subsequent electrolysis reactions.

[0220] In some embodiments of this application, in step (3), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH is from 3 to 6.5. For example, the solid content W 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 figures. For example, the pH of the slurry can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. By controlling the solid content W1 and pH of the slurry in step (3) within the above ranges, it is possible to avoid the continuous generation of sulfuric acid and the resulting H+ during subsequent electrolysis treatment due to the electrolysis rate exceeding the dissolution rate. + The accumulation of these deposits can then affect subsequent electrolytic processing.

[0221] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C, and the time t2 is 0.5h to 2h. For example, the temperature T2 of the dissolution reaction can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the time t2 of the dissolution reaction can be 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 T2 and time t2 of the dissolution reaction within the above ranges, it is beneficial to fully dissolve the solid filter material to obtain a slurry with the desired solid content.

[0222] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9×(N2+0.5N7)≤N1≤1.1×(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4". For example, N1 can be 0.90×(N2+0.5N7), 0.91×(N2+0.5N7), 0.92×(N2+0.5N7), 0.93×(N2+0.5N7), 0.94×(N2+0.5N7), 0.95×(N2+0.5N7), 0.96×(N2+0.5N7), 0.97×(N2+0.5N7), 0.98×(N2+0.5N7), 0.99×(N2+0.5N7), 1 ...9×(N2+0.5N7), 7) 1.01×(N2+0.5N7), 1.02×(N2+0.5N7), 1.03×(N2+0.5N7), 1.04×(N2+0.5N7), 1.05×(N2+0.5N7), 1.06×(N2+0.5N7), 1.07×(N2+0.5N7), 1.08×(N2+0.5N7), 1.09×(N2+0.5N7) or 1.1×(N2+0.5N7), or any two of the above numbers. The total number of moles of Me and lithium in the liquid phase is basically the same as the number of moles of sulfuric acid. During the dissolution process, Me can be converted into MeSO4, and then sulfuric acid with a molar number of Me can be generated during the electrolysis process. In the subsequent dissolution and electrolysis process, only sulfuric acid corresponding to the number of moles of lithium needs to be added. Therefore, the overall consumption of sulfuric acid is small, which improves the economic benefits of recovery.

[0223] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt, and manganese in the solid filter material is N5, where N1 < N5. For example, N1 can be 0.9N5, 0.85N5, 0.8N5, 0.7N5, 0.6N5, 0.5N5, 0.4N5, 0.3N5, ​​etc. To ensure that the pH of the slurry meets the requirements and to better initiate electrolysis directly, the difference between N1 and N5 can be larger, and the undissolved solid filter material can be dissolved using sulfuric acid generated by electrolysis. For example, 0.4N5 ≤ N1 ≤ 0.8N5.

[0224] In some embodiments of this application, in step (3), the sulfuric acid is commercially available concentrated sulfuric acid.

[0225] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0226] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0227] In some embodiments of this application, in step (4), adding solid filter media to the slurry during the electrolytic treatment process involves adding solid filter media and sulfuric acid to the slurry. Preferably, the solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and to maintain the pH of the slurry in the range of 3 to 5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry 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; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or between any two of the above numbers.

[0228] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry 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 3 to 6.5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry 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; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or between any two of the above numbers.

[0229] The addition of washed solid filter media (mainly containing Me / MeO and a small amount of Li2CO3) to the slurry serves two purposes. First, the added solid filter media can continuously react with the H2SO4 generated by electrolysis, thus consuming the H2SO4 in the system. +Maintaining the pH of the system within the aforementioned range ensures the normal operation of the electrolysis process. Furthermore, the generation of H2SO4 during slurry electrolysis allows for the continued dissolution of newly added solid filter media, increasing the throughput. Most of the H2SO4 is recycled, with only a small portion of the sulfuric acid consumed by lithium, reducing the overall H2SO4 usage and enabling the electrolysis reaction to proceed continuously. Additionally, no reducing agent is required during electrolysis, reducing its use and saving process steps. Therefore, by adding solid filter media and sulfuric acid to maintain the slurry's solid content and pH within the aforementioned range, the dissolution and electrolysis reactions can proceed continuously, including continuous electrolysis or cessation after a certain period, while avoiding the negative impact of continuous sulfuric acid generation on H2SO4 levels. + The accumulation of sediment can affect the normal operation of the electrolytic process. In some embodiments of this application, solid filter media and sulfuric acid are added to the slurry, and step (4) includes any one of the following three methods:

[0230] Method 1: Solid filter media and sulfuric acid are continuously added to the slurry. When the first preset condition is reached, a portion of the electrolyzed slurry is discharged. The lithium element in the electrolyzed slurry is purified to obtain mother liquor, which is then returned to the slurry in step (4) for continued electrolysis, allowing the electrolysis to continue without stopping. Preferably, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, where the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. In Method 1, the sulfuric acid generated by electrolysis and the added sulfuric acid can dissolve more solid filter media, enabling the dissolution reaction to continue. Simultaneously, as the electrolysis reaction proceeds, Li₂CO₃ reacts to form Li₂SO₄ in the liquid phase of the slurry, enriching it and increasing the lithium ion concentration. A portion of the slurry needs to be discharged. However, discharging this portion reduces the content of Me (e.g., Ni and / or Co) in the system. Therefore, the purified mother liquor from the discharged slurry is added back into 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 helps maintain the Ni and / or Co ion concentration in the liquid phase 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 lithium ion concentration in the electrolyzed slurry is too low, it indicates that the reaction is incomplete, and if the lithium ion concentration is too high, it will affect the electrolysis reaction. Therefore, when the first preset condition meets 0.7C2≤C1<C2, a portion of the electrolyzed slurry is 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.

[0231] In some embodiments of this application, C2 can be from 335 g / L to 345 g / L.

[0232] In some embodiments of this application, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V. For example, V' can be 0.01V, 0.03V, 0.05V, 0.07V, 0.1V, 0.12V, 0.15V, 0.17V, or 0.20V, or any two of the above values. Having the volume of the electrolyzed slurry discharged each time within the above range is beneficial because it allows the electrolysis and dissolution reactions to proceed simultaneously and continuously during the recovery process, achieving uninterrupted continuous recovery and improving recovery rate and production capacity.

[0233] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) for further electrolytic treatment. The purification treatment is evaporation, concentration, and crystallization. Specifically, the filtrate is heated, and a certain amount of water is evaporated to precipitate lithium sulfate crystals, thus extracting the lithium element from the filtrate. The resulting mother liquor mainly includes Ni and / or Co elements. Adding the mother liquor to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste in the recovery process. More importantly, the Ni and / or Co elements in the mother liquor can keep the ion concentration of Ni and / or Co elements in the liquid phase of the slurry dynamically within a relatively constant range. Furthermore, the return of the mother liquor can keep the liquid level in the electrolytic cell stable. Therefore, returning it to the slurry ensures that the electrolytic reaction can continue without stopping, which is beneficial for achieving continuous recovery without interruption. This application does not have any particular limitation on the temperature of the heated filtrate, as long as the purpose of this application can be achieved.

[0234] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) for further electrolytic treatment. The purification treatment includes carbonization deposition. Specifically, a carbonizing agent is added to the filtrate for carbonization deposition. The carbonizing agent can be one or more of sodium carbonate, potassium carbonate, and carbon dioxide. The filtrate is carbonized to obtain a lithium-containing salt, a nickel-containing and / or cobalt-containing salt, and mother liquor, thereby realizing the recovery of lithium. After lithium extraction by 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. Before returning to the slurry, the nickel / cobalt carbonate can be dissolved with sulfuric acid to improve the recovery rate of nickel and cobalt. More importantly, the dissolved nickel / cobalt elements can keep the ion concentration of Ni and / or Co elements in the liquid phase of the slurry in a relatively constant range to ensure that the electrolysis reaction can continue without stopping. Moreover, returning the mother liquor can also keep the liquid level in the electrolytic cell stable. When the carbonizing agent is selected from sodium carbonate, it is best to remove the sodium sulfate in the mother liquor before returning it to the slurry. Of course, the sodium can be removed after the sodium in the mother liquor has accumulated to a certain extent, and then the reaction can be carried out in the slurry.

[0235] In this application, the method for removing sodium from the mother liquor generally involves evaporating and crystallizing the mother liquor before returning it to the system to separate most of the sodium as sodium sulfate, after which the remaining mother liquor is returned to the slurry. This process does not strictly limit the method of sodium removal from the mother liquor; those skilled in the art can choose appropriate sodium removal methods according to actual needs.

[0236] Method 2: Add solid filter media and sulfuric acid to the slurry, and stop the electrolysis treatment when the second preset condition is reached. Preferably, the second preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.9C2≤C1<C2, where the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. In Method 1 above, the sulfuric acid generated by electrolysis and the added sulfuric acid can dissolve more solid filter media, allowing the dissolution reaction to continue. Simultaneously, as the electrolysis reaction proceeds, Li2CO3 reacts to form Li2SO4 in the liquid phase of the slurry, enriching the lithium ion concentration. When the lithium ion concentration in the electrolyzed slurry satisfies 0.9C2≤C1<C2, i.e., close to the theoretical saturation concentration, the electrolysis reaction becomes difficult to continue, and the electrolysis treatment stops. Specifically, C1 can be 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.

[0237] Method 3: Add solid filter media and sulfuric acid to the slurry. After a period of time, stop feeding. Stop electrolysis when the third preset condition is reached. When solid filter media and sulfuric acid are added for a period and then stopped, the amount consumed by the dissolution reaction gradually decreases. The sulfuric acid produced during electrolysis cannot be consumed in time, resulting in the amount of sulfuric acid produced by the electrolysis reaction exceeding the amount consumed by the dissolution reaction. As the reaction continues, sulfuric acid gradually accumulates, causing the pH of the system to decrease. Simultaneously, as the electrolysis and dissolution reactions proceed, nickel and / or cobalt are produced at the cathode. After feeding is stopped, the Co produced during dissolution... 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 current density also gradually decreases. Therefore, when the third preset condition is any one of the following conditions (1) to (3), the electrolysis reaction stops, and the element recovery can be completed: (1) the pH of the electrolyzed slurry is less than or equal to 3; (2) the total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (3) the current density during the electrolysis process is less than or equal to 8 mA / cm². 2 Of course, those skilled in the art can also choose other suitable third preset conditions according to actual needs.

[0238] In some embodiments of this application, in step (4), adding solid filter media to the slurry during the electrolysis process is called adding solid filter media to the slurry. Preferably, the solid filter media is added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and to maintain the pH of the slurry in the range of 3 to 6.5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry 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; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or between any two of the above numbers. When freshly added washed solid filter media (Me / MeO, Li2CO3) are added to the slurry, the added solid filter media can continuously react with the H2SO4 generated by electrolysis, thus consuming the H2SO4 in the system. +Maintaining the pH of the system within the above range ensures the normal operation of the electrolysis process. On the other hand, H2SO4 is generated during the slurry electrolysis process, which can continue to dissolve the newly added solid filter material, increasing the processing capacity of the solid filter material. Most of the H2SO4 is recycled, and only a small portion of the sulfuric acid is consumed by the lithium element, reducing the overall amount of H2SO4 used and enabling the electrolysis reaction to proceed continuously. Furthermore, no reducing agent is added during the electrolysis process, reducing the use of reducing agent and saving process steps. Thus, by adding solid filter material to maintain the solid content and pH of the slurry within the above range, the dissolution reaction and electrolysis reaction can continue for a period of time until the lithium element in the added solid filter material consumes all the sulfuric acid, and the electrolysis process stops. In some embodiments of this application, solid filter material is added to the slurry, and step (4) includes the following method four: adding solid filter material to the slurry, and stopping the electrolysis process when the fourth preset condition is reached. When only solid filter material is added, the lithium element in the solid filter material will continue to consume sulfuric acid. As the reaction continues, the amount of sulfuric acid decreases, causing the pH of the system to increase. Simultaneously, as the electrolysis and dissolution reactions proceed, nickel and / or cobalt are produced at the cathode, while Co is produced during dissolution due to the continuous consumption of sulfuric acid. 2+ And / or Ni 2+ The amount will gradually decrease as the reaction proceeds and the Co produced by dissolution... 2+ And / or Ni 2+ The amount will be 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+ The concentration will decrease, and the current density will also gradually decrease. Therefore, when the fourth preset condition is any one of the following conditions (4) to (6), the electrolysis reaction stops, and the element recovery can be completed: (4) the pH of the electrolyzed slurry is greater than or equal to 6.5; (5) the total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (6) the current density during the electrolysis process is less than or equal to 8 mA / cm. 2 Of course, those skilled in the art can also choose other suitable fourth preset conditions according to actual needs.

[0239] In some embodiments of this application, solid filter media is added when the total mass of nickel and / or cobalt in the cathode product increases by m1. In some embodiments of this application, solid filter media and sulfuric acid are added when the total mass of nickel and / or cobalt in the cathode product increases by m1. Wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter media in step (3). 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, solid filter media is added while the electrolysis reaction is taking place, or solid filter media and sulfuric acid are added while the electrolysis reaction is taking place, which is beneficial for achieving continuous recovery. As another example, m1 = 0.1m0, that is, solid filter media is added when a certain amount of product is produced at the cathode, or solid filter media and sulfuric acid are added.

[0240] In some embodiments of this application, the amount of supplementary solid filter media 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 supplementary solid filter media 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 N3, and the total molar amount of nickel and / or cobalt in the supplementary solid filter media is N4, where 0.95N3 ≤ N4 ≤ 1.05N3. For example, N4 can be 0.95N3, 0.96N3, 0.97N3, 0.98N3, 0.99N3, N3, 1.01N3, 1.02N3, 1.03N3, 1.04N3, or 1.05N3, or any two of the above numbers.

[0241] In some embodiments of this application, the amount of sulfuric acid added is determined based on the amount of lithium in the added solid filter media. The amount of sulfuric acid added corresponds to the amount of lithium in the added solid filter media; for example, the molar amount of sulfuric acid added is substantially the same as the molar amount of lithium in the added solid filter media. Specifically, the molar amount of lithium in the added solid filter media is N5, and the molar amount of sulfuric acid added is N6, where 0.45N5 ≤ N6 ≤ 0.55N5. For example, N6 can be 0.45N5, 0.46N5, 0.47N5, 0.48N5, 0.49N5, 0.50N5, 0.51N5, 0.52N5, 0.53N5, 0.54N5, or 0.55N5, or any two of the above numbers. The molar amount of sulfuric acid is expressed as the molar amount of "H2SO4".

[0242] Currently, there are several methods for recycling ternary cathode materials from spent batteries. One method involves adding carbon to the spent ternary cathode material, continuously introducing CO2 during roasting, and then carbonizing it during water leaching. This converts Li to Li₂CO₃, separating it from other elements. Other elements such as nickel, cobalt, and manganese are then separated and extracted using acid leaching followed by extraction. This process requires the addition of additional carbon source, and the subsequent separation of nickel, cobalt, and manganese consumes acid and alkali, resulting in significant resource consumption. Another method involves reducing the ternary cathode material powder by introducing one or more of carbon monoxide, nitrogen, and natural gas during roasting. After water leaching to obtain a lithium-rich solution, resin purification is performed, followed by the introduction of carbon dioxide. The remaining residue is then acid-dissolved, precipitated, and extracted for recovery. This method requires two steps for lithium extraction, and nickel, cobalt, and manganese require additional acid-alkali treatment and extraction, also resulting in high resource consumption.

[0243] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0244] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0245] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate.

[0246] The solid filter media includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0247] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0248] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0249] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0250] In some embodiments of this application, in step (2), the washing is acid washing.

[0251] The recycling method provided in this application has a simple processing flow and can reduce the amount of acid used, resulting in low resource consumption.

[0252] This application also provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0253] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0254] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550℃ to 700℃, then acid-washed and filtered to obtain solid filter material and lithium-containing filtrate; the molar ratio of lithium element in the positive electrode powder to hydrogen element in the acid used in acid washing is 1:(1.3 to 2).

[0255] Solid filter media include elemental Me and oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0256] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0257] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0258] In this application, the positive electrode refers to a positive electrode whose active material is mainly LiMeO2, wherein Me is selected from at least one of the elements Ni, Co, and Mn. For example, the positive electrode of a ternary lithium battery or a lithium cobalt oxide battery.

[0259] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner. In this application, the reducing agent is selected from carbon monoxide, which can be commercially available conventional carbon monoxide gas.

[0260] The recycling method provided in this application first recovers lithium from waste ternary lithium batteries, thereby achieving liquid-solid separation of lithium and nickel, cobalt, and manganese. Specifically, when the reducing agent is carbon monoxide (CO), the reaction 2LiMeO2 + 2CO = Li2CO3 + Me + MeO + CO2 occurs. CO reacts with LiMeO2 to generate CO2, which then reacts with C in the cathode powder to generate CO. This CO2 continues to react with the cathode powder, removing the carbon and reducing the nickel, cobalt, and manganese. Then, the lithium and nickel, cobalt, and manganese are separated by acid washing. The resulting solid filter material mainly consists of nickel, cobalt, and manganese metal (Me) and its oxide (MeO). The solid filter material containing Me and MeO is then dissolved and electrolyzed using sulfuric acid. During the acid dissolution and electrolysis process, the slurry maintains a certain solid content. This is because if all the solid filter material were to be dissolved by acid, an excess of sulfuric acid would be required, which would affect the pH of the electrolysis (usually less than 3), making electrolysis impossible. During the slurry electrolysis process, acid-washed solid filter media can be continuously replenished, thus achieving a cyclical recycling process. Alternatively, the feeding can be stopped after electrolysis for a period of time as needed, meaning the replenishment of acid-washed solid filter media will cease, and the electrolysis process will stop. In both of these processes, sulfuric acid is generated during electrolysis, significantly reducing sulfuric acid consumption compared to traditional processes.

[0261] In this process, due to the use of acid washing, the lithium elution rate in the lithium-containing filtrate is very high, reaching 95%–99%. The solid filter media contains no lithium or almost no lithium. Therefore, during subsequent acid dissolution and electrolysis of the acid-washed solid filter media, almost no lithium is removed. + Consuming sulfuric acid, or even if there are trace amounts of Li... + It consumes sulfuric acid but has almost no effect on acid dissolution and electrolysis, allowing it to continue uninterrupted, or rather, even if it needs to be stopped, it is only after a long period of operation (e.g., 20-30 days). In other words, such a trace amount of Li... + The content is negligible in actual production processes.

[0262] When carbon (C) powder is used as the reducing agent, the reaction 2LiMeO2 + C = Li2CO3 + Me + MeO occurs, removing carbon from the cathode powder and reducing nickel, cobalt, and manganese. The process is similar to when CO is used as the reducing agent, and will not be elaborated further here. When using carbon powder as the reducing agent, an inert gas, such as nitrogen, is introduced to facilitate the reduction roasting process.

[0263] Specifically, in the recovery method provided in this application, the dissolution and electrolysis processes of the solid filter media Me / MeO are carried out in the same electrolytic cell or connected containers. Since sulfuric acid is generated during the electrolysis process, the H2SO4 produced can continuously dissolve the newly added solid filter media Me / MeO, allowing for full utilization of the sulfuric acid and reducing acid consumption. In this process, the amount of sulfuric acid used is significantly reduced compared to traditional processes, which often require SO4 in combination with Co, Ni, and Mn. 2- If calculated using sulfur (S), 1 mol of Co / Ni / Mn corresponds to 1 mol of S, thus requiring a corresponding amount of S to match the molar amounts of Co, Ni, and Mn. However, in the recovery method provided in this application, Li is almost completely removed during the acid washing step, and the sulfuric acid consumed by Me / MeO during the dissolution process corresponds to (equal in amount to) the H2SO4 generated during electrolysis. Therefore, no additional S is needed, thus reducing the consumption of sulfuric acid. Consequently, the overall demand for sulfuric acid or acidic substances is reduced during the recovery process.

[0264] In addition, in step (2), the heat treatment temperature T1 is between 550°C and 700°C. For example, the heat treatment temperature T1 can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, or 700°C, or any two of the above numbers. When the heat treatment temperature is too low, for example below 550°C, the structure of LiMeO2 cannot be destroyed, the reaction is insufficient, and most of the trivalent Me ions cannot be converted into divalent Me ions. When the heat treatment temperature is too high, for example above 700°C, most of the Li element will volatilize, resulting in a significant reduction in the Li recovery rate and causing economic losses. Therefore, by controlling the heat treatment temperature T1 within the above range, the reducing agent can react fully with LiMeO2, the lithium element recovery rate is high, and thus the economic benefits of the recycling process can be improved. Simultaneously, the molar ratio X of lithium in the cathode powder to hydrogen in the acid used for pickling is 1:(1.3 to 2). For example, the molar ratio X can be 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2, or any two of the above ratios. A molar ratio X within this range is beneficial for fully eluting lithium from the heat-treated cathode powder, facilitating its subsequent entry into the lithium-containing filtrate. This results in a higher lithium recovery rate during subsequent lithium recovery through the filtrate, and reduces the elution of elemental Me and oxide MeO, minimizing the entry of Me into the liquid phase, which would affect the Me recovery rate and the Li content in the liquid phase. This improves the economic efficiency of the recovery process; simultaneously, it reduces the lithium content in the solid filter material, which is beneficial for subsequent electrolysis reactions and allows the acid dissolution electrolysis process to continue.

[0265] This application does not impose any particular restrictions on the method of obtaining the positive electrode of the waste battery, as long as it can achieve the purpose of this application. For example, it can be obtained by dismantling the waste battery or by purchasing it directly.

[0266] In this application, when the reducing agent is selected from CO, the heat treatment in step (2) includes the following reactions: 2CO+2LiMeO2=Li2CO3+Me+MeO+CO2↑; CO2+C=2CO↑.

[0267] In this application, the dissolution reaction in step (3) includes the following reactions: Me + H2SO4 = H2 + MeSO4; MeO + H2SO4 = H2O + MeSO4.

[0268] In this application, when Me is selected from Ni, Co, and Mn (i.e., the waste battery is a nickel-cobalt-manganese ternary battery), the electrolytic treatment in step (4) includes the following reactions: 2NiSO4+2H2O=2Ni+2H2SO4+O2↑ 2CoSO4+2H2O=2Co+2H2SO4+O2↑ NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4 CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0269] In one possible example, for an 811 ternary battery, after reduction and calcination of the solid filter material, Ni and Co elements mainly exist in elemental state, while Mn element mainly exists in oxide MnO state:

[0270] The dissolution reactions include: 8Ni + Co + MnO + 10H₂SO₄ = 8NiSO₄ + CoSO₄ + MnSO₄ + H₂O + 9H₂↑

[0271] The electrolysis reaction is: 8NiSO4 + CoSO4 + MnSO4 + 10H2O = 8Ni + Co + MnO2 + 10H2SO4 + 4O2↑;

[0272] Therefore, the overall reaction formula for dissolution and electrolysis includes the reaction shown in the following formula, in which elemental Ni and Co are transformed from the slurry into cathode products: 8Ni+Co+MnO+9H2O=8Ni+Co+MnO2+9H2↑+4O2↑.

[0273] As can be seen from the above reaction formula, although sulfuric acid is consumed in the dissolution reaction, an equal amount of sulfuric acid is generated in the electrolysis process. Therefore, no additional sulfuric acid needs to be added in the entire recovery process, which reduces the amount of sulfuric acid consumed.

[0274] Other ternary batteries are similar, such as the ternary 622 lithium-ion battery and the ternary 523 lithium-ion battery, which will not be discussed further here.

[0275] In another possible example, for lithium cobalt oxide batteries, the solid filter material consists of elemental Co and oxide CoO, and the total reaction anode produces O2 without consuming sulfuric acid;

[0276] Specifically, when Me is Co (i.e., the waste battery is a lithium cobalt oxide battery), the electrolytic treatment in step (4) includes the following reaction: 2CoSO4+2H2O=2Co+2H2SO4+O2↑;

[0277] The overall reaction equations are: 2CoO=2Co+O2↑; 2Co+2H2O=2Co+2H2↑+O2↑

[0278] In some embodiments of this application, the waste battery is a waste ternary nickel-cobalt-manganese battery, and the anode product includes manganese dioxide.

[0279] In some embodiments of this application, in step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min. For example, the flow rate V of carbon monoxide can be 1L / min, 1.2L / min, 1.4L / min, 1.5L / min, 1.6L / min, 1.8L / min, 2L / min, 2.2L / min, 2.4L / min, 2.5L / min, 2.6L / min, 2.8L / min, or 3L / min, or any two of the above numbers. By controlling the flow rate V of carbon monoxide within the above range, on the one hand, CO reacts fully with LiMeO2, which is beneficial for separating lithium elements in the subsequent acid washing process; on the other hand, residual carbon in the positive electrode powder can be removed. The resulting solid filter material is basically free of lithium elements and carbon, which is beneficial for improving the recovery rate of Me elements.

[0280] In some embodiments of this application, in step (2), the reducing agent is selected from carbon powder, and the mass ratio of positive electrode powder to carbon powder is 100:(8 to 15). For example, the mass ratio of positive electrode powder to carbon powder can be 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, or 100:15, or any two of the above numbers. By adjusting the mass ratio of positive electrode powder to carbon powder within the above range, the carbon powder reacts fully with LiMeO2, which is beneficial for separating lithium elements in the subsequent acid washing process.

[0281] In this application, the source of the reducing agent is not strictly limited. For example, CO can be purchased directly, or it can be CO prepared by combining oxalic acid and concentrated sulfuric acid, or CO prepared by other methods. The source of carbon is similarly not strictly limited.

[0282] In some embodiments of this application, in step (2), the heat treatment time t1 is between 1 h and 3 h. For example, the heat treatment time t1 can be 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, or 3 h, or any two of the above values. By adjusting the heat treatment time t1 within the above range, CO and / or C can fully react with LiMeO2, converting trivalent Me ions into divalent Me ions, which is beneficial to improving the recovery rate of Me element; moreover, lithium element is not easily volatilized, and the recovery rate of lithium element is high when recovering lithium element through lithium-containing filtrate in the subsequent process. Thus, the economic benefits of the recovery process can be improved.

[0283] In some embodiments of this application, in step (2), the acid is selected from sulfuric acid. Using sulfuric acid for pickling can improve the lithium elution rate, thus increasing the lithium recovery rate during subsequent lithium-containing filtrate recovery. Simultaneously, it can reduce the lithium content in the solid filter material, which is beneficial for subsequent electrolysis. This application does not limit the concentration of sulfuric acid during pickling, as long as it achieves the purpose of this application. For example, the concentration of sulfuric acid is 1 mol / L to 6 mol / L.

[0284] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 95% to 99%. For example, the lithium elution rate of the lithium-containing filtrate can be 95%, 96%, 97%, 98%, or 99%, or between any two of the above figures. A lithium elution rate within the above range indicates that after acid washing, the lithium element is essentially retained in the lithium-containing filtrate, thus increasing the lithium recovery rate during subsequent lithium element recovery from the filtrate. Simultaneously, it can reduce the lithium content in the solid filter material, which is beneficial for the continued progress of the subsequent electrolysis reaction.

[0285] In some embodiments of this application, in step (3), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH is from 3 to 6.5. For example, the solid content W 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 figures. For example, the pH of the slurry can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. By controlling the solid content W1 and pH of the slurry in step (3) within the above ranges, it is possible to avoid the continuous generation of sulfuric acid and the resulting H+ during subsequent electrolysis treatment due to the electrolysis rate exceeding the dissolution rate. + Accumulation can lead to problems that affect subsequent electrolytic treatment. During the initial preparation of the slurry, maintaining a pH of 3 to 6.5 is beneficial for the smooth initiation of the electrolysis process.

[0286] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C, and the time t2 is 0.5h to 2h. For example, the temperature T2 of the dissolution reaction can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the time t2 of the dissolution reaction can be 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 T2 and time t2 of the dissolution reaction within the above ranges, it is beneficial for the cathode powder to be fully dissolved to obtain a slurry with the desired solid content.

[0287] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt, and manganese in the liquid phase is N2, satisfying 0.9N2≤N1≤1.1N2. For example, N1 can be 0.90N2, 0.91N2, 0.92N2, 0.93N2, 0.94N2, 0.95N2, 0.96N2, 0.97N2, 0.98N2, 0.99N2, N2, 1.01N2, 1.02N2, 1.03N2, 1.04N2, 1.05N2, 1.06N2, 1.07N2, 1.08N2, 1.09N2, or 1.1N2, or any two of the above numbers. The total number of moles of Me in the liquid phase is basically the same as the number of moles of sulfuric acid. That is, when the solid filter material is dissolved by sulfuric acid, the Me element can be converted into MeSO4 during the dissolution process, allowing the Me element to enter the liquid phase. Then, sulfuric acid can be generated during the electrolysis process. No additional sulfuric acid needs to be added during the subsequent dissolution and electrolysis processes. That is, only sulfuric acid with a total number of moles of Me is added during the initial dissolution reaction. There is no sulfuric acid consumption in the later electrolysis / dissolution processes. Therefore, the overall sulfuric acid consumption is low, which improves the economic benefits of the recovery.

[0288] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 40°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0289] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0290] In some embodiments of this application, in step (4), solid filter media is added to the slurry during the electrolytic treatment. Preferably, the solid filter media is added to the slurry during the electrolytic treatment 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 3 to 5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry 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; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or between any two of the above numbers.

[0291] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry 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 3 to 6.5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry 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; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or between any two of the above numbers. When acid-washed solid filter media (Me / MeO) is newly added to the slurry, the added solid filter media can continuously react with the H2SO4 generated by electrolysis, thus consuming the H2SO4 in the system. + Maintaining the pH of the system within the aforementioned range ensures the normal operation of the electrolysis process. Furthermore, the generation of H2SO4 during slurry electrolysis allows for the continued dissolution of newly added solid filter media (Me / MeO), increasing the throughput of solid filter media. The recycling of H2SO4 reduces the overall amount used, enabling the electrolysis reaction to proceed continuously. Additionally, the absence of a reducing agent during electrolysis reduces its usage and saves process steps. Therefore, by adding solid filter media to maintain the slurry's solid content and pH within the aforementioned range, the dissolution and electrolysis reactions can continue (including continuous electrolysis or cessation after a certain period), and the continuous generation of sulfuric acid can prevent the formation of H2SO4. + This accumulation can hinder the normal operation of the electrolytic process.

[0292] In some embodiments of this application, solid filter media is added when the total mass of nickel and / or cobalt in the cathode product increases by m1; wherein m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter media in step (3). 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, solid filter media is added while the electrolysis reaction is being carried out, which is beneficial for achieving continuous recovery. For example, m1 = 0.1m0, that is, when the cathode produces a certain amount of product, solid filter material is added.

[0293] In some embodiments of this application, the amount of supplementary solid filter media 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 supplementary solid filter media 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 N3, and the total molar amount of nickel and / or cobalt in the supplementary solid filter media is N4, where 0.95N3 ≤ N4 ≤ 1.05N3. For example, N4 can be 0.95N3, 0.96N3, 0.97N3, 0.98N3, 0.99N3, N3, 1.01N3, 1.02N3, 1.03N3, 1.04N3, or 1.05N3, or any two of the above numbers.

[0294] In some embodiments of this application, in step (4), solid filter material is continuously added to the slurry so that the electrolysis process continues without stopping. During the slurry electrolysis process, H2SO4 is generated, which can continue to dissolve the newly added solid filter material (Me / MeO). H2SO4 is recycled, so that the electrolysis reaction and dissolution reaction can continue.

[0295] In some embodiments of this application, in step (4), solid filter material is added to the slurry, and after a period of time, the feeding is stopped. Electrolysis is stopped when preset conditions are met. In this process, those skilled in the art can arbitrarily set preset conditions according to actual needs. Preferably, the preset condition is: the pH of the electrolyzed slurry is less than or equal to 3. For example, the pH of the electrolyzed slurry can be 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.7, 2.9 or 3, or any two of the above numbers. When the pH of the electrolyzed slurry is less than or equal to 3, it indicates that a large amount of sulfuric acid has accumulated during the electrolysis process, affecting the continued progress of the electrolysis reaction. At this time, electrolysis can be stopped. In this application, the above "period of time" can be selected according to actual conditions, and this application does not limit it.

[0296] In some embodiments of this application, in step (4), solid filter media is added to the slurry, and after a period of time, the feeding is stopped. Electrolysis is stopped when a preset condition is reached. Preferably, the preset condition is that the total mass concentration C of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%. For example, the total mass concentration C can be 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.045%, 0.049%, or 0.05%, or between any two of the above values. When the total mass concentration C of nickel ions and / or cobalt ions is less than or equal to 0.05%, it indicates that the Me element has been basically recovered, and electrolysis can be stopped at this time. In this application, the above-mentioned "period of time" can be selected according to the actual situation, and this application does not limit it.

[0297] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T4 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, or any two of the above numbers. For example, the time t4 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 the positive electrode material layer of the obtained 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 have any particular limitation on the particle size of the positive electrode material layer powder, as long as it can achieve the purpose of this application.

[0298] In some embodiments of this application, in step (4), 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.

[0299] In some embodiments of this application, in step (4), the anode product includes either manganese dioxide or oxygen.

[0300] In some embodiments of this application, the waste battery is one or more of waste ternary nickel-cobalt-manganese batteries or waste lithium cobalt oxide batteries.

[0301] Example

[0302] 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.

[0303] Test methods and equipment:

[0304] Purity test:

[0305] Cathode products: Digested with acid and then analyzed by ICP. Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis. When the purity of the cathode products is greater than or equal to 99%, it is recorded as "greater than 99%".

[0306] Calculation of elution rate:

[0307] The Li content in the cathode powder and the Li content in the washed solid filter media were determined by ICP. The Li elution recovery rate was calculated as (1 - Li content in the washed solid filter media / Li content in the cathode powder) × 100%.

[0308] The elution rates of other elements can be calculated similarly.

[0309] In this process, the elution rate is sometimes also referred to as the elution recovery rate.

[0310] X-ray diffraction (XRD) test:

[0311] The solid filter media was tested using an X-ray diffractometer, and the XRD pattern was obtained. The XRD test was conducted using a Rigaku Uitima IV X-ray diffractometer (Japan), with a copper target and Kα rays as the testing conditions.

[0312] Preparation of positive electrode powder:

[0313] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn0.1 The O2) is disassembled, and the resulting positive electrode material layer is crushed and sieved to obtain positive electrode material layer powder. The positive electrode material layer powder is pretreated in a rotary kiln at T4 = 550℃ by introducing air to remove residual conductive agent and binder. The pretreatment time is t4 = 2h. Then, it is passed through a 150-mesh sieve to obtain positive electrode powder. The mass percentage of lithium in the positive electrode powder is 6.9%.

[0314] Unless otherwise specified, the positive electrode powder prepared above was used in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4.

[0315] Example 1-1

[0316] Figure 2 is a flowchart of the experiment in Example 1-1. The specific steps are as follows:

[0317] 10g of positive electrode powder was used for reduction. The positive electrode powder was placed in a quartz boat and then placed in a tube furnace. 100g of oxalic acid was added to a flask, and 5ml of concentrated sulfuric acid was added dropwise to the flask before heating. Before entering the tube furnace, anti-backflow devices, sodium hydroxide solution bottles, and concentrated sulfuric acid bottles were set up to absorb CO2 and water. The temperature was set to T5 = 150℃ for CO preparation. The temperature of the tube furnace was set to T1 = 700℃. When the temperature reached T1, CO was introduced at a flow rate V = 2L / min for a duration of t1 = 90min (1.5h). After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 hour. After each wash, the material was filtered, and then washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the washing solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material containing Me and MeO (Ni, Co, NiO, CoO, MnO); the elution rate of Li was approximately 98.74%. In the initial 10 g of cathode powder, the total mass m0 of nickel and cobalt was approximately 5 g (the nickel and cobalt content in 811 lithium-ion battery cathode powder is approximately 50 wt%). Figure 1 shows the XRD pattern of the solid filter material. The figure shows peaks for MnO, Co / Ni metal, and CoO / NiO, indicating that most of the metallic Me was reduced, facilitating subsequent dissolution and electrolysis reactions.

[0318] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid, and water was added to prepare a slurry with a solid content of W = 10 g / L. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. The anode plate was a lead-silver alloy, and the cathode plate was 316 stainless steel. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the electrolytic slurry was controlled at 4. During electrolysis, for every 0.1 Ah of electrolysis (approximately 0.1069 g of nickel-cobalt produced at the cathode), 0.142 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 75%) was added. After 24 hours of electrolysis, feeding was stopped. Electrolysis was stopped when the total concentration C of nickel-cobalt ions in the electrolyzed slurry was less than 0.05 wt%.

[0319] The cathode product, a nickel-cobalt alloy, produced by electrolysis has a purity of over 99%, while the anode product is manganese dioxide.

[0320] Table 1-1 Note: The “content of each element in the washed solid filter media in mg / kg” in Table 1-1 refers to how many mg of that element are contained in 1 kg of solid filter media.

[0321] Examples 1-2

[0322] 10g of positive electrode powder was used for reduction. The positive electrode powder and solid oxalic acid were mixed together and placed in a quartz boat, which was then placed in a tube furnace. The mass ratio of positive electrode powder to oxalic acid, Y, was 10:1. 100g of oxalic acid was added to a flask, and 5ml of concentrated sulfuric acid was added dropwise before heating. Before entering the tube furnace, anti-backflow devices, sodium hydroxide solution bottles, and concentrated sulfuric acid bottles were used to absorb CO2 and water. The temperature was set to T5 = 150℃ for CO preparation. The temperature of the tube furnace was set to T1 = 700℃. When the temperature reached T1... CO was introduced at a flow rate of V = 2.5 L / min for a duration of t1 = 90 min. After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 hour. After each wash, the material was filtered, and then washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the washing solution was measured. The washing was completed when the pH reached 7, yielding solid filter media. The elution recovery rate of Li was 99%. The total mass m0 of nickel and cobalt in 10 g of cathode powder was approximately 5 g.

[0323] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. The anode plate was a lead-silver alloy, and the cathode plate was 316 stainless steel. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the electrolytic slurry was controlled at 4. During electrolysis, every 0.1 Ah (approximately 0.1069 g of nickel-cobalt produced at the cathode) was replenished with 0.142 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 75%). This replenishment ensured continuous dissolution and electrolysis. This example, Li... + The high recovery rate allows it to continue electrolysis indefinitely.

[0324] The nickel-cobalt alloy produced by electrolysis has a purity of over 99%, and the anode product is manganese dioxide.

[0325] Examples 1-3

[0326] Except for the following parameters which differ from those in Example 1-1, all other parameters are the same as in Example 1-1:

[0327] The temperature of the tubular furnace is set at T1 = 550℃;

[0328] The CO flow rate is as follows: for every 10g of positive electrode powder, the carbon monoxide flow rate V = 2.5L / min; the heat treatment duration t1 = 60min;

[0329] The solid filter media was acid-dissolved using 40 ml of 2.0 mol / L sulfuric acid, and water was added to prepare a slurry with a solid content of W = 5 g / L.

[0330] Electrolysis was carried out at a pH of 4.5, with the electrolysis temperature controlled at T3 = 60℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis.

[0331] In this embodiment, the elution recovery rate of Li was 95.8%, and the purity of the nickel-cobalt alloy produced by electrolysis reached over 99%.

[0332] Examples 1-4

[0333] Except for the following parameters which differ from those in Example 1-1, all other parameters are the same as in Example 1-1:

[0334] The temperature of the tubular furnace is set at T1 = 600℃;

[0335] The CO flow rate is as follows: for every 10g of positive electrode powder, the flow rate of carbon monoxide introduced is V = 1L / min, and the heat treatment duration is t1 = 180min;

[0336] The solid filter media was acid-dissolved using 50 ml of 1.6 mol / L sulfuric acid, and water was added to prepare a slurry with a solid content of W = 12 g / L.

[0337] Electrolysis was carried out with the pH controlled at 3.5, the electrolysis temperature controlled at T3 = 60℃, and a voltage of 3.5V for nickel-cobalt electrolysis.

[0338] During the electrolysis process, for every 1Ah of electrolysis (approximately 1.069g of cathode product nickel and cobalt), 1.42g of solid filter media (with a nickel and cobalt mass fraction of approximately 75%) is added after washing with water.

[0339] In this embodiment, the elution recovery rate of Li was 95.2%, and the purity of the nickel-cobalt alloy produced by electrolysis reached over 99%.

[0340] Examples 1-5

[0341] Except for the mass ratio of cathode powder to oxalic acid being 5:1, everything else is the same as in Examples 1-2. The mass of the cathode powder is 10g.

[0342] In this embodiment, the elution recovery rate of Li was 98.7%, and the purity of the nickel-cobalt alloy produced by electrolysis reached over 99%.

[0343] Table 1-2

[0344] Comparative Example 1-1 (CO was introduced in a normal manner, compared with Example 1-1)

[0345] 10g of cathode powder was used for reduction. The cathode powder was loaded into a quartz boat and placed in a tube furnace. CO gas was continuously introduced at a flow rate of V = 2L / min, and the tube furnace temperature was set to T1 = 700℃ for 90min. After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500ml of water for 1h. After each wash, the material was filtered, and then washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding solid filter media. The elution recovery rate of Li was 85%. The total mass of nickel and cobalt in the 10g cathode powder was m0 = 5g.

[0346] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid, and water was added to prepare a slurry with a solid content of W = 10 g / L. Part of the liquid phase of the slurry was fed into an electrolytic cell for electrolysis. The anode plate was a lead-silver alloy, and the cathode plate was 316 stainless steel. The pH of the electrolytic slurry was controlled at 4, and the electrolysis temperature was controlled at T3 = 70℃. A voltage of 3.5V was used for nickel-cobalt electrolysis. During electrolysis, 1.42 g of washed solid filter media was required to replenish the slurry every 1 Ah. Due to the low elution rate of Li ions, some sulfuric acid was consumed by the Li ions. Even with continuous replenishment, the total concentration of nickel and cobalt ions in the slurry would fall below 0.05% after a period of electrolysis, making continuous electrolysis impossible.

[0347] Comparative Examples 1-2 (reduction temperature 500℃)

[0348] 10g of positive electrode powder was used for reduction. The positive electrode powder was placed in a quartz boat and then placed in a tube furnace. 100g of oxalic acid was added to a flask, and 5ml of concentrated sulfuric acid was added dropwise before heating. Before entering the tube furnace, anti-backflow devices, sodium hydroxide solution bottles, and concentrated sulfuric acid bottles were used to absorb CO2 and water. The temperature was set at T5 = 150℃ to prepare CO. The temperature of the tube furnace was set at T1 = 500℃. When the temperature reached T1, CO was introduced and the duration was t1 = 90min. After cooling, the calcined material was taken out and washed with water at a solid-liquid ratio of 1:50, using 500ml of water for 1 hour. After each wash, the material was filtered and washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding solid filter media. The elution recovery rate of Li was 30%.

[0349] When the solids were dissolved in acid using 20 ml of 4.8 mol / L sulfuric acid, most of the solids could not be dissolved and the electrolytic reaction could not be carried out effectively.

[0350] Comparing Comparative Examples 1-2 with Example 1-1, it can be seen that when the reduction temperature T1 is too low, the reduction of the cathode powder is incomplete, and the lithium element cannot be effectively separated from the cathode powder, resulting in a low lithium recovery rate and the inability to effectively carry out subsequent dissolution and electrolysis reactions.

[0351] Comparative Examples 1-3 (reduction temperature 800℃)

[0352] 10g of positive electrode powder was used for reduction. The positive electrode powder was placed in a quartz boat and then placed in a tube furnace. 100g of oxalic acid was added to a flask, and 5ml of concentrated sulfuric acid was added dropwise before heating. Before entering the tube furnace, anti-backflow devices, sodium hydroxide solution bottles, and concentrated sulfuric acid bottles were used to absorb CO2 and water. The temperature was set at T5 = 150℃ to prepare CO. The temperature of the tube furnace was set at T1 = 800℃. When the temperature reached T1, CO was introduced at a flow rate V = 2L / min for a duration of t1 = 90min. After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50 using 500ml of water for 1 hour. After each wash, the material was filtered and washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding solid filter media. The Li recovery rate was 50%, as most of the Li volatilized due to the high temperature.

[0353] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid, and water was added to prepare a slurry with a solid content of W = 10 g / L. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. The anode plate was a lead-silver alloy, and the cathode plate was 316 stainless steel. The pH of the slurry was controlled at 4 during electrolysis, and the electrolysis temperature was controlled at T3 = 70℃. A voltage of 3.5V was used for nickel-cobalt electrolysis. During electrolysis, 1.42 g of washed solids was added every 1 Ah. After feeding was stopped, electrolysis was stopped when the total concentration of nickel-cobalt ions in the electrolyzed slurry decreased to 0.05 wt%.

[0354] The purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0355] Comparing Comparative Examples 1-3 with Example 1-1, it can be seen that when the reduction temperature T1 is too high, lithium volatilizes, reducing the lithium recovery rate. However, the resulting solid filter material has a high degree of reduction and can undergo subsequent dissolution and electrolysis reactions.

[0356] Comparative Examples 1-4

[0357] Except for the following parameters which differ from those in Example 1-1, all other parameters are the same as in Example 1-1:

[0358] The solid filter media obtained in Example 1-1 was acid-dissolved using 25 ml of 4.8 mol / L sulfuric acid, and then approximately 100 ml of water was added to prepare a slurry with a solid content of W = 0.1 g / L and a pH of approximately 2.

[0359] At the start of electrolysis, bubbles were observed to form on the cathode plate, and gradually, obvious bubbles appeared on the cathode plate. This was because there was too little positive electrode powder and too much acid in the slurry, which could not neutralize the sulfuric acid produced by electrolysis, preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0360] As can be seen from Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4, the recovery method provided in this application can effectively recover lithium, nickel, cobalt, and manganese from the ternary cathode. The nickel-cobalt alloy has high purity, and the elution recovery rate of Li is high, which is also beneficial for the recovery of lithium. At the same time, the consumption of sulfuric acid is low during the recovery process, resulting in high economic benefits.

[0361] Preparation of positive electrode powder:

[0362] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn 0.1 The O2) is disassembled, and the resulting positive electrode material is crushed and sieved to obtain positive electrode material layer powder. The positive electrode material layer powder is pretreated in a rotary kiln at T4 = 550℃ by introducing air to remove residual conductive agent and binder. The pretreatment time is t4 = 2h. Then, it is passed through a 150-mesh sieve to obtain positive electrode powder. The lithium content in the positive electrode powder is 7.2% by mass.

[0363] Unless otherwise specified, the positive electrode powder prepared above was used in Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-3.

[0364] Example 2-1 (Method 3)

[0365] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90min (1.5h). After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500ml of water for 1h. After each wash, the material was filtered, and the solid-liquid ratio was repeated for three washes. The pH of the solution was measured, and the washing was completed when the pH reached 7. The filtered material yielded a solid filter media and a lithium-containing filtrate. The solid filter media contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The ICP data of the obtained solid filter media are shown in Table 2-1. Table 2-1 shows that the elution rate of Li is approximately 85%. The lithium-containing filtrate after washing was evaporated to obtain solid Li2CO3.

[0366] The XRD pattern of the calcined material is shown in Figure 4. It can be seen from the figure that there are characteristic peaks of MnO, Co, Ni and Li2CO3, indicating that the nickel, cobalt and manganese metals are reduced relatively thoroughly, that is, reduced to low-valence metals that are easily soluble in acid, which facilitates subsequent dissolution and electrolysis reactions.

[0367] The solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of approximately 5.2. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4 during the electrolysis process. For every 1 Ah of electrolysis (approximately 1.069 g of nickel-cobalt cathode product), 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 78% and a lithium mass percentage of 1.4%) needs to be added, along with 0.27 ml of sulfuric acid (4.8 mol / L). After 24 hours of electrolysis, feeding is stopped. The cathode product is a high-purity nickel-cobalt alloy, and the anode product is MnO2. Electrolysis is stopped when the total concentration of nickel-cobalt ions in this embodiment decreases to 0.05 wt%. The purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0368] Table 2-1

[0369] Example 2-2 (Method 1)

[0370] 10g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2.5 L / min. The tube furnace temperature was set at T1 = 650℃, and the heating duration was t1 = 120 min (2 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:80, using 800 ml of water for 1 h. After each wash, the powder was filtered, and then washed again with water at a solid-liquid ratio of 1:80. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate. The solid filter material contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The elution rate of Li was 88%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0371] The solid filter media was acid-dissolved using 8 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 15 g / L and a pH of approximately 5.3. The slurry (volume V = 500 ml) obtained after partial acid dissolution of the solid filter media was fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode and a lead-silver alloy plate was used as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During the electrolysis process, every 1 Ah of electrolysis (approximately 1.069 g of nickel-cobalt cathode products) required the addition of 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 80% and a lithium mass percentage of 1.5%), along with 0.28 ml of sulfuric acid (concentration 4.8 mol / L). After continuous electrolysis for a period of time, the cathode product is a high-purity nickel-cobalt alloy with a purity of over 99%, and the anode product is MnO2. After the lithium sulfate concentration in the electrolytic slurry is reduced to 250 g / L, 50 ml of the electrolytic slurry is discharged, and 30 wt% of water is evaporated for concentration and crystallization. After filtration, solid lithium sulfate and mother liquor are obtained. The mother liquor is returned to the slurry to maintain ion balance and allow electrolysis to continue without stopping.

[0372] The theoretical saturation concentration of lithium sulfate in the electrolytically treated slurry is calculated as 340 g / L.

[0373] Examples 2-3 (Method Two)

[0374] 20g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 1 L / min. The tube furnace temperature was set at T1 = 600℃, and the heating duration was t1 = 150 min (2.5 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:50, using 1000 ml of water for 1 h. After each wash, the powder was filtered, and then washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate. The solid filter material contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The elution rate of Li was 90%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0375] Solid filter media was acid-dissolved using 17 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 13 g / L and a pH of approximately 5.3. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During electrolysis, for every 1 Ah (approximately 1.069 g of nickel-cobalt produced at the cathode), 1.28 g of washed solid filter media (approximately 81% nickel-cobalt mass fraction and 1.6% lithium mass percentage) was added, along with 0.3 ml of 4.8 mol / L sulfuric acid. The cathode product was a high-purity nickel-cobalt alloy with a purity exceeding 99%, and the anode product was MnO2. Electrolysis is stopped once the lithium sulfate concentration in the slurry reaches 320 g / L. The slurry after electrolysis is stopped can be completely discharged, evaporated, concentrated, and crystallized to obtain lithium sulfate and mother liquor. The mother liquor can be reused for the next electrolysis.

[0376] The theoretical saturation concentration of lithium sulfate in the electrolytically treated slurry is calculated as 340 g / L.

[0377] Examples 2-4 (Method Four)

[0378] 10g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90 min (1.5 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 h. After each wash, the powder was filtered, and the solid-liquid ratio was repeated at 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate containing Me and MeO (mainly including Ni, Co, and MnO), as well as Li2CO3. The elution rate of Li was 85%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0379] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of approximately 5.2. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During electrolysis, for every 1 Ah (approximately 1.069 g of nickel-cobalt produced at the cathode), 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 78%) needed to be added. The cathode product was a high-purity nickel-cobalt alloy, and the anode product was MnO2. As the reaction proceeded, the sulfuric acid was gradually converted to Li... + Electrolysis is stopped when the pH of the electrolyzed slurry reaches 6.5. The purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0380] Examples 2-5

[0381] 10g of the prepared cathode powder was mixed with 1g of carbon powder and placed in a quartz boat, which was then placed in a tube furnace. N2 was first introduced for a period of time until all other gases in the tube were exhausted. Heating was then initiated, with N2 continuously introduced throughout the process. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90 min (1.5 h). After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 h. After each wash, the material was filtered, and the solid-liquid ratio was repeated at 1:50. After three washes, the pH of the solution was measured. Washing was completed when the pH reached 7. Filtration yielded a solid filter media and a lithium-containing filtrate. The solid filter media contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li₂CO₃. ICP testing of the solid filter media showed a Li elution rate of 86%. The washed lithium solution was then evaporated to obtain solid Li₂CO₃.

[0382] The XRD pattern of the calcined material is similar to that in Example 2-1, with characteristic peaks of MnO, Co, Ni, and Li2CO3, indicating that nickel, cobalt, and manganese metals can also be reduced using carbon powder, which facilitates subsequent dissolution and electrolysis reactions.

[0383] The subsequent acid dissolution and electrolysis processes are the same as in Example 2-1, and the purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0384] Comparative Example 2-1

[0385] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started. The CO flow rate was V = 2L / min, the tube furnace temperature was set at T1 = 500℃, and the heating duration was t1 = 90min. After cooling, the calcined material was removed and washed with water. The washing process was the same as in Example 2-1. The elution rate of Li in the lithium-containing filtrate obtained after washing was 22%. The solid filter material obtained after washing was prepared into a slurry using sulfuric acid. It was found that most of the solids could not be dissolved by acid and could not effectively carry out the electrolytic reaction.

[0386] Comparing Comparative Example 2-1 with Example 2-1, it can be seen that when the reduction temperature T1 is too low, the reduction of the cathode powder is incomplete, and the lithium element cannot be effectively separated from the cathode powder, resulting in a low lithium recovery rate and the inability to effectively carry out subsequent dissolution and electrolysis reactions.

[0387] Comparative Example 2-2

[0388] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 800℃, and the heating duration was t1 = 90 min. After cooling, the calcined material was removed and washed with water, the same as in Example 2-1. The elution rate of Li in the lithium-containing filtrate obtained after washing was 45%, indicating that most of the Li volatilized due to the high temperature.

[0389] The subsequent acid dissolution and electrolysis processes are the same as in Example 2-1.

[0390] Comparing Comparative Example 2-2 with Example 2-1, it can be seen that when the reduction temperature T1 is too high, lithium volatilizes, reducing the lithium recovery rate. However, the resulting solid filter material has a high degree of reduction and can undergo subsequent dissolution and electrolysis reactions.

[0391] Comparative Examples 2-3

[0392] Except for the following parameters which differ from those in Example 2-1, all other parameters are the same as in Example 2-1:

[0393] Acid dissolution was performed using 25 ml of 4.8 mol / L sulfuric acid, followed by the addition of approximately 100 ml of water to prepare a slurry with a solid content of W = 0.1 g / L and a pH of approximately 2.

[0394] At the start of electrolysis, bubbles were observed to form on the cathode plate, and gradually, obvious bubbles appeared on the cathode plate. This was because there was too little positive electrode powder and too much acid in the slurry, which could not neutralize the sulfuric acid produced by electrolysis, preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0395] From Examples 2-1 to 2-5, and Comparative Examples 2-1 to 2-2, when the recovery method provided in this application is used, the elution rate of Li in the lithium-containing filtrate is higher than that of the comparative examples. Furthermore, since sulfuric acid is generated during the electrolysis process, the consumption of sulfuric acid is greatly reduced compared to traditional processes, resulting in high economic benefits from the recovery. In addition, by controlling the heat treatment temperature within the range specified in this application, the elution rate of Li can reach 85%, achieving full recovery of lithium.

[0396] Preparation of positive electrode powder:

[0397] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn 0.1 The process involves disassembling O2, crushing and sieving the resulting positive electrode material layer to obtain positive electrode material layer powder. This powder is then pretreated in a rotary kiln at T4 = 550℃ with air to remove residual conductive agents and binders for t4 = 2 hours. The powder is then passed through a 150-mesh sieve to obtain the positive electrode powder. The lithium content in the positive electrode powder is 6.9 wt%.

[0398] Unless otherwise specified, the positive electrode powder prepared above was used in Examples 3-1 to 3-11 and Comparative Examples 3-1 to 3-5.

[0399] Example 3-1

[0400] Figure 6 is a flowchart of the experiment in Example 3-1. The specific steps are as follows:

[0401] The prepared cathode powder was ground, and 100g was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90min (1.5h). After cooling, the material was taken out for XRD testing. The test results are shown in Figure 5, indicating that the nickel, cobalt, and manganese elements in the material were completely reduced after calcination. Then, acid washing was performed using sulfuric acid aqueous solution. The concentration of the sulfuric acid aqueous solution was 4.88mol / L, and the volume was 150ml. The molar ratio X of lithium element in the cathode powder to hydrogen element in the sulfuric acid during acid washing was approximately 1:1.46. After filtration, solid filter material and lithium-containing filtrate were obtained. The ICP data of the obtained solid filter material (Me / MeO) are shown in Table 3-1. Table 3-1 shows that the elution rate of Li is approximately 96.3%, which facilitates subsequent dissolution and electrolysis reactions.

[0402] Solid filter media was acid-dissolved using 100 ml of 4.88 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of 5.3. This partially acid-dissolved slurry was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the electrolytic slurry was controlled at 4. During electrolysis, 1.3 g of acid-washed solid filter media (with a nickel-cobalt mass fraction of approximately 85%) was added every 1 Ah (approximately 1.069 g of nickel-cobalt was produced as cathode product). After 24 hours of electrolysis, feeding was stopped. The cathode product was a high-purity nickel-cobalt alloy, and the anode product was MnO2. Electrolysis was stopped when the total concentration C of nickel-cobalt ions in the electrolyzed slurry decreased to 0.05 wt%. The purity of the nickel-cobalt alloy produced as the cathode product exceeded 99%.

[0403] Table 3-1

[0404] Example 3-2

[0405] The prepared cathode powder was ground, and 100g was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90 min (1.5 h). After cooling, the powder was removed and acid-washed with sulfuric acid aqueous solution. The concentration of the sulfuric acid aqueous solution was 4.88 mol / L, and the volume was 180 ml. The molar ratio X of lithium in the cathode powder to hydrogen in the sulfuric acid during acid washing was approximately 1:1.76. After filtration, a solid filter material and a lithium-containing filtrate were obtained. The elution rate of Li in the lithium-containing filtrate was 99%. The obtained solid filter material (Me / MeO) is suitable for subsequent dissolution and electrolysis reactions.

[0406] Solid filter media was acid-dissolved using 100 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of 5.3. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. The anode plate was a lead-silver alloy, and the cathode plate was 316 stainless steel. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the electrolytic slurry was controlled at 4. During electrolysis, 1.3 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 85%) was added every 1 Ah of electrolysis (approximately 1.069 g of cathode product). This replenishment ensured continuous dissolution and electrolysis. In this example, the Li+ elution rate was high, allowing for continuous electrolysis. The purity of the nickel-cobalt alloy produced by electrolysis reached over 99%.

[0407] Examples 3-3 to 3-11

[0408] Except for adjusting the relevant preparation parameters according to Table 3-2, the rest is the same as in Example 3-1. Among them, in Examples 3-9 to 3-11, carbon powder is used as a reducing agent, and during the heat treatment of the cathode powder and the reducing agent, nitrogen gas is first introduced until other gases in the exhaust tube are vented, and then heating begins. Throughout the entire process, that is, during the reduction roasting process, nitrogen gas is continuously introduced.

[0409] Comparative Examples 3-1 to 3-5

[0410] Except for adjusting the relevant preparation parameters according to Table 3-2, everything else is the same as in Example 3-1. Specifically:

[0411] Comparative Example 3-1

[0412] During the acid dissolution process, the concentration of the sulfuric acid aqueous solution was 4.88 mol / L and the volume was 112 ml. The molar ratio X of lithium element in the positive electrode powder to hydrogen element in sulfuric acid during acid washing was approximately 1:1.09. At this time, the amount of acid was relatively small, so the residual Li2CO3 content in the solid filter material was relatively large, and the elution rate of Li in the lithium-containing filtrate was only 78%.

[0413] During subsequent acid dissolution and electrolysis of the solid filter media, the Li in the slurry + This cannot be ignored; it will consume sulfuric acid, and the Li in the slurry... + When the concentration reaches a certain level, it affects electrolysis, making the recovery process unsustainable.

[0414] Comparative Example 3-2

[0415] During the acid dissolution process, the concentration of the sulfuric acid aqueous solution was 4.88 mol / L and the volume was 256 ml. The molar ratio X of lithium in the cathode powder to hydrogen in the sulfuric acid during acid washing was approximately 1:2.5. At this point, the acid content was relatively high, resulting in a significant amount of Me / MeO dissolving into the liquid phase, which reduced the recovery rate of nickel, cobalt, and manganese. The elution rate of Li in the lithium-containing filtrate was 98%. Furthermore, the purity of Li₂SO₄ in the liquid phase also decreased due to the presence of MeSO₄ impurities, increasing the difficulty of subsequent purification.

[0416] Comparative Example 3-3

[0417] During the reduction roasting process, the roasting temperature T1 = 500℃ and the heating duration t1 = 90 min. The elution rate of Li in the lithium-containing filtrate obtained after acid washing was 37%. When the solid filter material obtained after acid washing was prepared into a slurry using sulfuric acid dissolution, it was found that most of the solids could not be dissolved by acid and could not be effectively electrolyzed.

[0418] Comparing Comparative Example 3-3 with Example 3-1, it can be seen that when the reduction temperature T1 is too low, the reduction of the cathode powder is incomplete, and the lithium element cannot be effectively separated from the cathode powder, resulting in a low lithium recovery rate and the inability to effectively carry out subsequent dissolution and electrolysis reactions.

[0419] Comparative Examples 3-4

[0420] During the reduction roasting process, the roasting temperature T1 = 800℃ and the heating duration t1 = 90 min. The lithium-containing filtrate obtained after acid washing contained 53% Li, indicating that most of the Li volatilized due to the high temperature.

[0421] The obtained solid filter media has a high degree of reduction of nickel, cobalt and manganese elements, which can be recovered by subsequent acid dissolution and electrolysis.

[0422] Comparative Examples 3-5

[0423] Similar to Example 3-1, the difference is that the material after reduction roasting is washed with water, as follows:

[0424] After cooling down, the material was removed and washed with water at a solid-liquid ratio of 1:50. 5000ml of water was used for 1 hour. After each wash, the material was filtered and washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was tested. The washing was completed when the pH reached 7, and solid filter material was obtained. The elution rate of Li was 85%.

[0425] During acid dissolution electrolysis, due to the low elution rate of Li ions, some Li ions will react with and consume some sulfuric acid (i.e., SO42-). 2- Even with continuous replenishment of the solid filter media after water washing, the total concentration of nickel and cobalt ions in the slurry will fall below 0.05% after a period of electrolysis, making it impossible for electrolysis to continue.

[0426] The preparation parameters and test data of each embodiment and comparative example are shown in Table 3-2.

[0427] Table 3-2 Note: “ / ” in Table 3-2 indicates that there are no corresponding preparation parameters or performance data; since the elution rate of Li in the lithium filtrate in Comparative Examples 3-1 to 3-5 was low, the purity of the cathode products was not tested.

[0428] Referring to Table 3-2, from Examples 3-1 to 3-11, and Comparative Examples 3-1 to 3-5, when the recovery method provided in this application is used, the elution rate of Li in the lithium-containing filtrate is higher than that of the comparative examples. Moreover, since sulfuric acid is generated during the electrolytic treatment, the consumption of sulfuric acid is greatly reduced compared with the traditional process. Therefore, the recovery has high economic benefits.

[0429] In addition, by controlling the heat treatment temperature within the range of this application, and by using acid washing, and by adjusting the molar ratio X of lithium element in the cathode powder to hydrogen element in the acid used in acid washing within the range of this application, the elution rate of Li can be as high as 95%, achieving full recovery of lithium element, and enabling the solid filter material obtained after acid washing to be continuously replenished and recovered without stopping, which has very high industrialization significance.

[0430] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article.

[0431] 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) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate. The solid filter media includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn; (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction. (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

2. The recycling method according to claim 1, comprising the following steps: (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; wherein the reducing agent is carbon monoxide obtained by heating a mixture of oxalic acid and concentrated sulfuric acid. The solid filter media comprises elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn; (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction. (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

3. The recycling method according to claim 2, wherein, In step (2), the flow rate of carbon monoxide introduced for every 10g of positive electrode powder is 1L / min to 3L / min; Preferably, in step (2), the heat treatment time t1 is 1 hour to 3 hours; Preferably, in step (2), the water washing satisfies at least one of the following conditions: Condition a: The solid-liquid ratio for water washing is 1:(10 to 100); Condition b: The washing process is completed when the pH of the washing solution after rinsing is 7 to 8; Preferably, in step (2), the positive electrode powder and oxalic acid are mixed first and then the prepared carbon monoxide is introduced, and the mass ratio of the positive electrode powder to oxalic acid is (5 to 10):

1. Preferably, in step (2), the lithium ion elution recovery rate of the lithium-containing filtrate is 95% to 99%.

4. The recycling method according to claim 2, wherein, In step (3), the solid content W of the slurry is 1 g / L to 50 g / L, and the pH is 3 to 6.5; preferably, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C, and the time t2 is 0.5 h to 2 h. Preferably, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, where 0.9N2≤N1≤1.1N2.

5. The recycling method according to claim 2, wherein, In step (4), the pH of the electrolytic treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V; Preferably, in step (4), the solid filter material is added to the slurry during the electrolysis process; More preferably, the solid filter media is added to the slurry 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 3 to 5.

6. The recycling method according to claim 5, wherein, When the mass of nickel and / or cobalt in the cathode product increases by m1, the solid filter material is added. Where m1 ≤ 0.1m0; Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the solid filter media in step (3).

7. The recycling method according to claim 6, wherein, The total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

8. The recycling method according to claim 5, wherein, In step (4), the solid filter material is continuously added to the slurry to ensure that the electrolysis process continues without stopping; or, The solid filter material is added to the slurry. After a period of time, the feeding is stopped. When the preset conditions are met, the electrolysis process is stopped.

9. The recycling method according to claim 8, wherein, The electrolysis process is stopped when a preset condition is met, and the preset condition is any one of the following: (1) The pH of the electrolyzed slurry is less than or equal to 3; (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%.

10. The recycling method according to claim 2, wherein, In step (1), the pretreatment includes crushing, screening and high-temperature treatment. The temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

11. The recycling method according to claim 2, wherein, In step (4), 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 either manganese dioxide or oxygen.

12. The recycling method according to claim 1, comprising the following steps: (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder; The solid filter media includes elemental Me, oxide MeO, and Li2CO3, wherein Me is selected from at least one of the elements Ni, Co, and Mn; (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction. (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

13. The recycling method according to claim 12, wherein, In step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of positive electrode powder to carbon powder is 100:(8 to 15). Preferably, in step (2), the heat treatment time t1 is 1 hour to 3 hours; Preferably, in step (2), the water washing satisfies at least one of the following conditions: Condition a: The solid-liquid ratio of the water washing is 1:(10 to 100), wherein the unit of solid in the water washing is g and the unit of liquid is ml; Condition b: The washing process is completed when the pH of the washing solution after the water washing is 7 to 8; Preferably, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%.

14. The recycling method according to claim 12, wherein, In step (3), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH is 3 to 6.5; Preferably, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h; Preferably, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9╳(N2+0.5N7)≤N1≤1.1╳(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

15. The recycling method according to claim 12, wherein, In step (4), the pH of the electrolytic treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V; Preferably, in step (4), at least the solid filter material is added to the slurry during the electrolysis process; More preferably, the solid filter media is added to the slurry 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 3 to 6.5; or, The solid filter media and sulfuric acid are added to the slurry 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 3 to 5.

16. The recycling method according to claim 15, wherein, When the mass of nickel and / or cobalt added to the cathode product is m1, the solid filter material is added, or the solid filter material and sulfuric acid are added. Where m1 ≤ 0.1m0; Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the sum of the mass of nickel and / or cobalt in the solid filter material added during the preparation of the slurry in step (3).

17. The recycling method according to claim 16, wherein, The total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

18. The recycling method according to claim 17, wherein, The number of moles of lithium in the added solid filter material is N5, and the number of moles of added sulfuric acid is N6, where 0.45N5≤N6≤0.55N5; The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

19. The recycling method according to claim 15, wherein, Step (4) includes any of the following methods: Method 1: Continuously add the solid filter material and sulfuric acid to the slurry. When the first preset condition is reached, discharge part of the electrolytically treated slurry and purify the lithium element in the electrolytically treated slurry to obtain mother liquor. Return the mother liquor to the slurry in step (4) to continue the electrolytic treatment, so that the electrolytic treatment continues without stopping. Method 2: Add the solid filter material and sulfuric acid to the slurry, and stop the electrolysis process when the second preset condition is reached; Method 3: Add the solid filter material and sulfuric acid to the slurry. After a period of time, stop feeding. Stop the electrolysis process when the third preset condition is reached. Method 4: Add the solid filter material to the slurry, and stop the electrolysis process when the fourth preset condition is reached.

20. The recycling method according to claim 19, wherein, In the first method, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. Preferably, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V; Preferably, after the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate, the lithium element in the filtrate is purified to obtain lithium salt and mother liquor, and the mother liquor is returned to the slurry in step (4) to continue the electrolytic treatment, wherein the purification treatment includes evaporation, concentration and crystallization or carbonization deposition.

21. The recycling method according to claim 19, wherein, In the second method, the second preset condition is the actual concentration C1 of lithium salt in the electrolyzed slurry, which satisfies 0.9C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

22. The recycling method according to claim 19, wherein, In the third method, the third preset condition is any one of the following conditions: (1) The pH of the electrolyzed slurry is less than or equal to 3; (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (3) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

23. The recycling method according to claim 19, wherein, In the fourth method, the fourth preset condition is any one of the following conditions: (4) The pH of the electrolyzed slurry is greater than or equal to 6.5; (5) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (6) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

24. The recycling method according to claim 1, comprising the following steps: (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then acid-washed and filtered to obtain solid filter material and lithium-containing filtrate; the molar ratio of lithium element in the positive electrode powder to hydrogen element in the acid used in the acid washing is 1:(1.3 to 2). The solid filter media comprises elemental Me and oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn; (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction. (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

25. The recycling method according to claim 24, wherein, In step (2), the reducing agent is selected from at least one of carbon monoxide and carbon powder; Preferably, the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of positive electrode powder to carbon powder is 100:(8 to 15). Preferably, in step (2), the heat treatment time t1 is 1 hour to 3 hours; Preferably, in step (2), the acid is selected from sulfuric acid; Preferably, in step (2), the lithium elution rate of the lithium-containing filtrate is 95% to 99%.

26. The recycling method according to claim 24, wherein, In step (3), the solid content W1 of the slurry is 1 g / L to 50 g / L and the pH is 3 to 6.5; Preferably, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h; Preferably, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, satisfying 0.9N2≤N1≤1.1N2.

27. The recycling method according to claim 24, wherein, In step (4), the pH of the electrolytic treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V; Preferably, in step (4), the solid filter material is added to the slurry during the electrolysis process; More preferably, the solid filter media is added to the slurry 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 3 to 5.

28. The recycling method according to claim 27, wherein, When the mass of nickel and / or cobalt in the cathode product increases by m1, the solid filter material is added. Where m1 ≤ 0.1m0; Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the sum of the mass of nickel and / or cobalt in the solid filter material added during the preparation of the slurry in step (3).

29. The recycling method according to claim 28, wherein, The total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

30. The recycling method according to claim 27, wherein, In step (4), the solid filter material is continuously added to the slurry to ensure that the electrolysis process continues without stopping; or, The solid filter material is added to the slurry. After a period of time, the feeding is stopped. When the preset conditions are met, the electrolysis process is stopped.

31. The recycling method according to claim 30, wherein, The electrolysis process is stopped when a preset condition is met, and the preset condition is any one of the following: (1) The pH of the electrolyzed slurry is less than or equal to 3; (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%.

32. The recycling method according to claim 24, wherein, In step (1), the pretreatment includes crushing, screening and high-temperature treatment. The temperature T4 of the high-temperature treatment is 300°C to 800°C, the time t4 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

33. The recycling method according to claim 24, wherein, In step (4), 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 any one of manganese dioxide and oxygen.

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