Method for recovering positive electrode of waste battery

Abstract

The recycling method provided by the application is used for recycling valuable metals in waste battery positive electrode powder. Sulfuric acid generated by electrolysis can be used to continue to dissolve more positive electrode powder in the slurry until the electrolysis ends when the sulfuric acid tends to be depleted. This self-sustaining process can reduce the use of sulfuric acid in the extraction process. In addition, while metals such as nickel and cobalt in the extraction slurry are extracted, the concentration of the first metal element remaining in the slurry increases, making it possible and effective to extract the first metal element. In addition, the recycling method provided by the application can also perform continuous electrolysis treatment, because the electrolysis generates sulfuric acid or supplemented sulfuric acid can dissolve more positive electrode powder, thereby improving the recovery rate and production capacity. Therefore, the whole recycling process is simple, economical and efficient, and the use of acid and alkali is reduced to reduce the impact on the environment, and it is an environmentally friendly recycling method.

Description

Technical Field

[0001] 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

[0002] With the continuous expansion of the electric vehicle and renewable energy markets, new energy batteries, as an important energy storage device, have been widely used in automobiles, power tools, mobile devices, and other fields due to their high energy density and long lifespan. However, the recycling and disposal of used batteries remains a global challenge. Once batteries are damaged or reach the end of their lifespan, a large number of used batteries are generated, posing potential pollution and resource waste problems to the environment. Therefore, developing an efficient and environmentally friendly recycling method is crucial.

[0003] Traditional recycling processes mainly include pyrometallurgy and hydrometallurgy. Pyrometallurgy extracts valuable metals or compounds from cathode materials through high-temperature treatment. While the process is simple, it has low recovery efficiency and product quality, and easily generates harmful gases that pollute the environment. Hydrometallurgy involves pre-treating the cathode material and then using processes such as acid leaching and extraction to enrich the valuable metals for recovery or utilization. These methods generally use large amounts of acids, alkalis, and extraction solutions, increasing recycling costs and resulting in low processing efficiency, making large-scale industrialization impossible. Summary of the Invention

[0004] The purpose of this application is to provide a method for recycling the positive electrode of waste batteries, which reduces the amount of sulfuric acid used in the recycling process, lowers recycling costs, and allows for continuous electrolysis through a refueling method. The specific technical solution is as follows:

[0005] The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0006] (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder;

[0007] (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry, the slurry containing a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone the dissolution reaction;

[0008] (3) The slurry is subjected to electrolytic treatment, during which at least the positive electrode powder and the reducing agent are added to the slurry; wherein, the electrolytic treatment produces sulfuric acid, and the sulfuric acid continues to undergo the dissolution reaction with the added positive electrode powder and the reducing agent;

[0009] (4) The electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry, wherein the cathode product includes nickel and / or cobalt.

[0010] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5.

[0011] In some embodiments of this application, in step (2), the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide; the conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h.

[0012] In some embodiments of this application, step (3), adding at least the positive electrode powder and the reducing agent to the slurry, includes: adding the positive electrode powder and the reducing agent to the slurry; or, adding the positive electrode powder, the reducing agent and sulfuric acid to the slurry.

[0013] In some embodiments of this application, in step (3), the positive electrode powder and the reducing agent are added, or the positive electrode powder, the reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.5.

[0014] In some embodiments of this application, steps (2) and (3) include:

[0015] (2) The slurry is obtained by mixing at least the positive electrode powder, sulfuric acid, the reducing agent, and water and carrying out a dissolution reaction. The temperature T1 of the dissolution reaction is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide.

[0016] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6. The temperature T2 of the electrolytic treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

[0017] In some embodiments of this application, the positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese;

[0018] When the mass of nickel and / or cobalt added to the cathode product is m1, the cathode powder and the reducing agent are added; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0019] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1;

[0020] The total number of moles of the second metal element in the added positive electrode powder is N3, and the number of moles of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3.

[0021] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, and the positive electrode powder and the reducing agent are added during the electrolysis process.

[0022] In some embodiments of this application, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, the reducing agent, and sulfuric acid are added during the electrolysis process.

[0023] In some embodiments of this application, sulfuric acid is added when the mass of nickel and / or cobalt added to the cathode product is m1; wherein, m1≤0.1m0; preferably, 0.0001m0≤m1≤0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2).

[0024] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7.

[0025] Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7); or,

[0026] When the reducing agent contains sulfur, the number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9×(0.5N5+0.5N7)≤N8+N6≤1.1×(0.5N5+0.5N7);

[0027] The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0028] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0029] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0030] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4.

[0031] Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4); or,

[0032] When the reducing agent contains sulfur, the number of moles of sulfur in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4);

[0033] The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0034] In some embodiments of this application, the electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element, and the filtrate is purified to obtain salt containing the first metal element; preferably, the filter residue is added to the slurry for further electrolysis.

[0035] In some embodiments of this application, the first metal element is selected from sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element; preferably, the concentrated mother liquor is added to the slurry for further electrolytic treatment.

[0036] In some embodiments of this application, the first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate, after carbonization deposition, yields at least a lithium-containing salt and a deposition mother liquor. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. Preferably, the deposition mother liquor is added to the slurry for further electrolytic treatment.

[0037] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment, wherein the temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

[0038] In some embodiments of this application, in step (3), the anode and cathode in the electrolytic process are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

[0039] In some embodiments of this application, in step (4), the anode product includes manganese dioxide.

[0040] In this application, the slurry that has undergone electrolysis can be the slurry during electrolysis or the slurry after electrolysis.

[0041] The beneficial effects of this application are:

[0042] The recycling method provided in this application is used to recover valuable metals, namely first and second metallic elements, from the positive electrode powder of spent batteries. The second metallic element, such as nickel and cobalt, contained in the acidic slurry is separated by electrolysis. The sulfuric acid produced by the electrolysis reaction can be used to further dissolve more positive electrode powder in the slurry; this self-sustaining process reduces the use of sulfuric acid in the extraction process. The method provided in this process allows electrolysis to continue through a feeding mechanism, for example, by feeding to allow electrolysis to continue for a period of time and then stop; or, for example, by feeding to allow electrolysis to continue without stopping. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and effective. In addition, the recycling method provided in this application allows for continuous electrolysis through feeding, because the sulfuric acid produced by electrolysis or the added sulfuric acid can dissolve more positive electrode powder, thereby improving the recovery rate and production capacity. The recycling method provided in this process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method. 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

[0043] 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.

[0044] Figure 1This is a flowchart of the experiment in Example 1;

[0045] Figure 2 This is a flowchart of the experiment in Example 2;

[0046] Figure 3 This is a flowchart of the experiment in Example 3;

[0047] Figure 4 This is the experimental flowchart for Example 5. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only 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.

[0049] In this process, the dissolution and electrolysis of the cathode powder take place in the same electrolytic cell / container or connected containers. This allows the H2SO4 generated during electrolysis to continuously dissolve newly added cathode powder, ensuring full utilization of sulfuric acid and reducing acid consumption. The amount of sulfuric acid used in this process is significantly reduced compared to traditional processes. Specifically, in traditional recovery processes, when sulfuric acid is used, elements such as Li, Na, Co, Ni, and Mn in the cathode powder all need to react with SO4. 2- The recovery of elements requires a combination of factors. If we consider sulfur (S) as an example, 2 mol of Li corresponds to 1 mol of S, 2 mol of Na corresponds to 1 mol of S, and 1 mol of Co (or Ni or Mn) corresponds to 1 mol of S. In other words, the molar amount of S needs to match the total molar amount of Li, Na, Co, Ni, and Mn. Therefore, a large amount of sulfuric acid is consumed during the recovery process, increasing the recovery cost. However, in this process, only the molar amount of S corresponding to the molar amount of Li is needed, thus reducing the overall demand for S, or in other words, reducing the demand for sulfuric acid or acidic substances. Based on this, this application provides a method for recycling the positive electrode of waste batteries to reduce the amount of sulfuric acid used in the recycling process and lower the recycling cost.

[0050] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0051] (1) Disassemble waste batteries to obtain positive electrode, and pre-treat the positive electrode to obtain positive electrode powder;

[0052] (2) At least positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the positive electrode powder that has not undergone the dissolution reaction.

[0053] (3) Electrolyze the slurry and add at least positive electrode powder and reducing agent to the slurry during the electrolysis process; wherein, sulfuric acid is generated during the electrolysis process, and the sulfuric acid continues to react with the added positive electrode powder and reducing agent to dissolve;

[0054] (4) Electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry, wherein the cathode product includes nickel and / or cobalt.

[0055] In some embodiments of this application, the cathode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese.

[0056] The recycling method provided in this application involves carrying out the dissolution reaction and electrolysis process in the same or connected containers. On one hand, by adding positive electrode powder and a reducing agent, the sulfuric acid generated during the electrolysis process can continuously dissolve the added positive electrode powder in the slurry, allowing the dissolution reaction and electrolysis to proceed simultaneously, thus increasing the amount of positive electrode powder that can be processed. On the other hand, because sulfuric acid is generated during the electrolysis process, the actual consumption of SO4 is reduced. 2- SO4 consumed only by the first metallic element in the cathode powder 2- That is, the overall reaction only needs to provide Li + Required SO4 2- That is, compared to traditional recycling processes that simultaneously consume both the first and second metal elements (SO4), 2- Technical solution: The SO4 recycling method of this application 2- The consumption of sulfuric acid is greatly reduced, thus reducing the demand for sulfuric acid. Consequently, the amount of sulfuric acid required throughout the recycling process is significantly reduced, lowering recycling costs. Furthermore, no harmful gases are generated during the entire recycling process, making it an environmentally friendly recycling method.

[0057] In this process, pretreated positive electrode powder, sulfuric acid and reducing agent are mixed and dissolved to form a slurry. The slurry contains a solid phase (i.e. undissolved positive electrode powder) and a liquid phase composed of various substances obtained after the dissolution reaction, sulfuric acid, water and so on.

[0058] In this application, a certain solid phase is always required in the slurry to avoid H+ precipitates due to the different rates of dissolution and electrolysis reactions. + The accumulation of [something] prevents electrolysis from occurring if the pH value is below the expected range.

[0059] In some embodiments of this application, in step (2), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH of the slurry is from 2 to 6.5. For example, the solid content W1 of the slurry can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or 6.5, or between any two of the above numbers.

[0060] By adjusting the pH of the slurry in step (2) within the above-mentioned range, the electrolysis process can proceed stably, because excessively high or low pH values ​​during electrolysis will affect the normal operation of the electrolysis process. For example, if the pH value is too low, H2 gas is easily generated during electrolysis, which will affect the electrolysis production of elemental metals; if the pH value is too high, there is a risk that the metal elements will form alkaline precipitates, which will also affect the normal operation of the electrolysis process.

[0061] By controlling the solid content W1 of the slurry in step (2) within the above range, the H+ content can be prevented from increasing due to the continuous generation of sulfuric acid during subsequent electrolytic treatment. + The accumulation of these deposits can then affect subsequent electrolytic processing.

[0062] Specifically, because the pH value needs to be within the range of 2 to 6.5 during electrolysis, and the electrolysis reaction often occurs rapidly, a large amount of H2SO4 (H+) can be produced in a short period of time. + The dissolution reaction is relatively slow. In this process, electrolysis is continued by feeding materials, and the slurry must always have a certain solid content. This is because if the cathode powder is completely dissolved throughout the process, the difference in reaction rates between the two reactions will result in a higher H₂ content during electrolysis. + Unable to react with the positive electrode powder in time, resulting in H + Excessive accumulation causes the pH of the electrolytic slurry to drop, making it unsuitable for electrolysis (at which point the electrolysis product is H2 instead of metal), and electrolysis cannot continue. Conversely, when the slurry contains some undissolved cathode powder, although the dissolution reaction rate is still slow, the increased amount of reactants results in a higher H2 consumption per unit time. + Increasing the pH level can keep the slurry pH within the required range, allowing electrolysis to continue.

[0063] In some embodiments of this application, in step (2), the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide. The conditions for the dissolution reaction are: temperature T1 is 40°C to 95°C; time t1 is 0.1h to 2h. For example, the temperature T1 of the dissolution reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the time t1 of the dissolution reaction can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. By controlling the temperature T1 and time t1 of the dissolution reaction within the above range, it is beneficial to fully dissolve the cathode powder to obtain the slurry with the desired solid content.

[0064] In some embodiments of this application, in step (2), the sulfuric acid is commercially available concentrated sulfuric acid.

[0065] In some embodiments of this application, the cathode material includes LiMO2 or NaMO2, where M is selected from at least one of Ni, Co, and Mn. When the cathode material includes LiMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of Li2SO4, NiSO4, CoSO4, MnSO4, H2O, and H2SO4. When the cathode material includes NaMO2, after the dissolution reaction, the liquid phase of the slurry includes at least one of NiSO4, CoSO4, MnSO4, H2O, H2SO4, and Na2SO4.

[0066] In some embodiments of this application, in step (2), in the liquid phase, the total number of moles of the first metal element in the positive electrode powder is P1, the total number of moles of the second metal element in the positive electrode powder is P2, the number of moles of sulfuric acid is P3, and the total number of moles of the first metal element in the reducing agent is P4. The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0067] Specifically, when the reducing agent does not contain sulfur (S), that is, the reducing agent is selected from hydrogen peroxide. The condition 0.9 × (0.5P1 + P2 + 0.5P4) ≤ P3 ≤ 1.1 × (0.5P1 + P2 + 0.5P4) must be met. For example, P3 can be 0.9 × (0.5P1 + P2 + 0.5P4), 0.92 × (0.5P1 + P2 + 0.5P4), 0.94 × (0.5P1 + P2 + 0.5P4), 0.95 × (0.5P1 + P2 + 0.5P4), 0.96 × (0.5P1 + P2 + 0.5P4), 0.98 × (0.5P1 + P2 + 0.5P4), 1 × The formulas are (0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above values. By adjusting the relationship between P1, P2, P3, and P4 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0068] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, the molar number of S in the reducing agent is P5, satisfying 0.9×(0.5P1+P2+0.5P4)≤P3+P5≤1.1×(0.5P1+P2+0.5P4). For example, P3+P5 can be 0.9×(0.5P1+P2+0.5P4), 0.92×(0.5P1+P2+0.5P4), 0.94×(0.5P1+P2+0.5P4), 0.95×(0.5P1+P2+0.5P4), 0.96×(0.5P1+P2+0.5P4), 0.98×(0.5P1+P2+0.5P4), 1 ×(0.5P1+P2+0.5P4), 1.02×(0.5P1+P2+0.5P4), 1.04×(0.5P1+P2+0.5P4), 1.06×(0.5P1+P2+0.5P4), 1.08×(0.5P1+P2+0.5P4), or 1.1×(0.5P1+P2+0.5P4), or any two of the above numbers. By adjusting the relationship between P1, P2, P3, P4, and P5 to satisfy the above relationship, it is beneficial to obtain a slurry with a solid content W1 of 1 g / L to 50 g / L and a pH of 2 to 6.5.

[0069] In this scheme, sulfuric acid is used to dissolve most of the positive electrode powder. The amount of sulfuric acid added is only enough to dissolve the preset amount of positive electrode powder that needs to be dissolved. A small portion of the positive electrode powder must remain undissolved (i.e., to ensure that a certain solid content is maintained in the slurry). This ensures that the dissolution reaction can be fully carried out during subsequent continuous feeding and electrolysis, avoids a decrease in the pH of the system, and keeps the pH within a suitable range during the electrolysis process, allowing the electrolysis to continue.

[0070] In some embodiments of this application, step (3) involves adding at least positive electrode powder and a reducing agent to the slurry in one of the following ways: adding positive electrode powder and a reducing agent to the slurry. Preferably, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide, and the positive electrode powder and reducing agent are added during the electrolysis process. On the one hand, a) when SO2 is used as a reducing agent, it can also act as an "S" source, converting into SO4 during the electrolysis process. 2- This ensures that the overall system does not consume sulfuric acid. Therefore, during electrolysis, only positive electrode powder and reducing agent need to be added, without the need to add sulfuric acid, allowing the slurry electrolysis to continue (or stop after a period of time, or continue without stopping). Consequently, the demand for sulfuric acid is further reduced throughout the recovery process, resulting in lower recovery costs. b) When hydrogen peroxide, sodium sulfite, sodium thiosulfate, or sodium metabisulfite are used as reducing agents, the overall reaction only requires the consumption of the first metallic element, such as Li. + The corresponding SO4 2- Compared to existing technologies where the first and second metal elements simultaneously consume SO4, 2- The technical solution reduces the amount of sulfuric acid required (especially for reducing agents such as sodium sulfite, sodium thiosulfate, and sodium metabisulfite, where the sulfuric acid requirement is further reduced). However, for these reducing agents, since only positive electrode powder and reducing agent are added, subsequent electrolysis can continue for a period of time. Electrolysis stops when the sulfuric acid is nearly exhausted. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ in the sulfuric acid produced during electrolysis. + The reaction proceeds while maintaining the pH value within the range necessary for normal electrolysis. A pH value that is too high or too low will affect the normal operation of the electrolysis process. Therefore, in this process, the added positive electrode powder, reducing agent, and sulfuric acid generated during electrolysis continuously undergo dissolution and electrolysis reactions, consuming the H₂ produced during electrolysis. + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+The ratio is relatively stable. Therefore, by continuously adding positive electrode powder, reducing agent and sulfuric acid produced by electrolysis, the pH of the slurry electrolysis can be adjusted without adding alkali to adjust the pH of the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities.

[0071] In some embodiments of this application, step (3) involves adding at least positive electrode powder and a reducing agent to the slurry in a second manner: adding positive electrode powder, a reducing agent, and sulfuric acid to the slurry. Preferably, the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, and sodium metabisulfite, and the positive electrode powder, reducing agent, and sulfuric acid are added during the electrolysis process. When the above-mentioned reducing agent is used, on the one hand, sulfuric acid will be generated during the electrolysis process, and on the other hand, as the electrolysis process proceeds, only the first metal element in the entire system will consume SO4. 2- This process consumes a portion of the sulfuric acid in the overall system. Replenishing this consumed sulfuric acid during electrolysis allows the electrolysis to continue uninterrupted. Of course, it also requires the replenishment of necessary positive electrode powder and reducing agent. However, since sulfuric acid is also generated during electrolysis, meaning only a portion of the sulfuric acid is consumed, the overall sulfuric acid requirement during the recovery process is relatively low compared to existing technologies that simultaneously consume SO4 from the first and second metal elements. 2- This technical solution reduces the demand for sulfuric acid and lowers recycling costs. On the other hand, the added positive electrode powder acts as an "alkali," reacting with the H+ in the sulfuric acid produced during electrolysis. + The reaction proceeds to ensure the pH value remains within the range necessary for normal electrolysis. A pH value that is too high or too low will negatively impact the electrolysis process. Therefore, this process utilizes the added positive electrode powder, reducing agent, and sulfuric acid to continuously undergo dissolution and electrolysis reactions with the sulfuric acid produced during electrolysis. This not only consumes the H₂ produced during electrolysis but also... + This ensures that the slurry pH is consistently maintained within the range suitable for normal electrolytic treatment, and allows for the dynamic and continuous production of substances such as Co, Ni, and MnO2. In particular, a stable Co / Ni ratio product is obtained at the cathode. This is primarily due to the continuous addition of cathode powder and reducing agent during the electrolytic process, which reduces the Co content in the slurry. 2+ / Ni 2+ The ratio is relatively stable; moreover, by adding sulfuric acid, electrolysis can be carried out continuously without interruption. Thus, by continuously adding positive electrode powder, reducing agent, and sulfuric acid, the pH of the slurry electrolysis can be adjusted without the need to add alkali to adjust the pH of the electrolysis process, reducing the amount of alkali used and avoiding the introduction of new impurities, allowing the electrolysis process to continue without interruption.

[0072] In some embodiments of this application, in step (3), positive electrode powder and reducing agent are added, or positive electrode powder, reducing agent and sulfuric acid are added, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.5. For example, the solid content W2 of the slurry can be maintained at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry can be maintained at 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 or 6.5, or between any two of the above numbers. During the electrolytic treatment process, the pH value of the slurry is maintained within the range of 2 to 6.5. The electrolytic reaction rate is relatively fast, and a large amount of H2SO4, i.e., H+, can be generated in a short period of time. + An increase in pH will decrease the pH value, and if the pH is too low, it will affect the electrolysis reaction rate. Generally, the dissolution reaction rate is slower than the electrolysis reaction rate. Therefore, to maintain the slurry solid content W2 within the range of 1 g / L to 50 g / L, the amount of H₂ consumed per unit time... + Increasing the concentration of the positive electrode powder, reducing agent, and optional sulfuric acid can maintain the slurry pH within the range of 2 to 6.5. This allows the dissolution and electrolysis reactions to continue, and also prevents the H+ from being reduced due to the continuous generation of sulfuric acid. + The accumulation of buildup can hinder the normal operation of the electrolytic process.

[0073] In some embodiments of this application, steps (2) and (3) include the following steps:

[0074] (2) A slurry is obtained by mixing at least positive electrode powder, sulfuric acid, a reducing agent, and water and carrying out a dissolution reaction. The dissolution reaction temperature T1 is 40°C to 95°C, the time t1 is 0.1h to 2h, the solid content W1 of the slurry is 2g / L to 50g / L, and the pH is 3 to 6. The reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, or any other suitable reducing agent that can promote the dissolution of the positive electrode powder in sulfuric acid and / or the subsequent electrolytic reaction to extract the metal or metal compound. For example, the dissolution reaction temperature T1 can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C, or any two of the above numbers. For example, the dissolution reaction time t1 can be 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. For example, the solid content W1 of the slurry can be 2g / L, 3g / L, 4g / L, 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 34g / L, 40g / L, 45g / L, or 50g / L, or any two of the above numbers. For example, the pH of the slurry can be 3, 3.5, 4, 4.5, 5, 5.5, or 6, or any two of the above numbers.

[0075] (3) The slurry is subjected to electrolytic treatment. During the electrolytic treatment, at least positive electrode powder and reducing agent are added to maintain the solid content W2 of the slurry within the range of 2 g / L to 50 g / L and the pH of the slurry within the range of 3 to 6. The electrolytic treatment temperature T2 is 20℃ to 95℃ and the voltage is 2.5V to 4.5V. For example, the solid content W2 of the slurry during the electrolytic treatment can be maintained at 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, or between any two of the above numbers. For example, the pH of the slurry during the electrolytic treatment can be maintained at 3, 3.5, 4, 4.5, 5, 5.5 or 6, or between any two of the above numbers. For example, the electrolytic treatment temperature T2 can be 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 95℃, or any two of the above numbers. For example, the electrolytic treatment voltage can be 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, 3V, 3.1V, 3.2V, 3.3V, 3.4V, 3.5V, 3.6V, 3.7V, 3.8V, 3.9V, 4V, 4.1V, 4.2V, 4.3V, 4.4V, or 4.5V, or any two of the above numbers.

[0076] In some embodiments of this application, the current density of the electrolysis process is 5 A / m. 2 Up to 500A / m 2 .

[0077] In some embodiments of this application, the electrolysis process is performed while the slurry is stirred at a speed of 50 rpm to 1000 rpm. For example, the stirring speed can be 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, or 1000 rpm, or any two of the above numbers. This allows the dissolution and electrolysis reactions to fully occur, thereby improving the recovery efficiency.

[0078] The recycling method of this application includes the above steps (2) and (3). During the recycling process, electrolysis can generate sulfuric acid. This self-sustaining process can reduce the use of sulfuric acid in the recycling process and reduce the recycling cost. In addition, the dissolution reaction and the electrolysis reaction work together. The added positive electrode powder consumes sulfuric acid through the dissolution reaction, so that the electrolysis reaction continues to proceed within a suitable pH range. The electrolysis reaction will generate sulfuric acid, which maintains the recycling of sulfuric acid. At the same time, it can continuously dissolve the newly added positive electrode powder so that the dissolution reaction continues, reducing the use of sulfuric acid and avoiding the introduction of excess alkaline impurities, further reducing the recycling cost, and continuously recovering elements in the positive electrode material.

[0079] In some embodiments of this application, when the mass of nickel and / or cobalt added to the cathode product is m1, cathode powder and reducing agent are added; wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0 or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, cathode powder and reducing agent are added while the electrolysis reaction is being carried out, which is beneficial to achieving continuous recovery. For example, m1 = 0.1m0, that is, when the cathode produces a certain amount of product, positive electrode powder and reducing agent are added.

[0080] In some embodiments of this application, the amount of added cathode powder is determined based on the amount of nickel and / or cobalt produced by electrolysis, and the total amount of nickel and / or cobalt contained in the added cathode powder is as similar as possible to the amount of nickel and cobalt metal produced. Specifically, the total molar amount of nickel and / or cobalt added to the cathode product is N1, and the total molar amount of nickel and / or cobalt in the added cathode powder is N2, where 0.95N1≤N2≤1.05N1. For example, N2 can be 0.95N1, 0.96N1, 0.97N1, 0.98N1, 0.99N1, N1, 1.01N1, 1.02N1, 1.03N1, 1.04N1, or 1.05N1, or any two of the above values. The amount of reducing agent added is determined based on the total amount of metals (e.g., at least one of nickel, cobalt, and manganese) to be reduced in the added cathode powder. Specifically, the total molar amount of the second metal element in the added positive electrode powder is N3, and the molar amount of the added reducing agent is N4, satisfying 0.25N3≤N4≤3N3. For example, N4 can be 0.25N3, 0.5N3, 0.75N3, 1N3, 1.25N3, 1.5N3, 1.75N3, 2N3, 2.25N3, 2.5N3, 2.75N3, or 3N3, or any two of the above numbers. By adjusting N3 and N4 to meet the above ranges, the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L and the pH is maintained in the range of 2 to 6.5 during the electrolysis process, so as to ensure the continuous operation of the electrolysis process.

[0081] In some embodiments of this application, when the mass of nickel and / or cobalt added to the cathode product is m1, positive electrode powder, reducing agent, and sulfuric acid are added; wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the mass of nickel and / or cobalt in the positive electrode powder added in step (2). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0, or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, the positive electrode powder, reducing agent and sulfuric acid are added while the electrolysis reaction is taking place, which is beneficial to achieving continuous recovery. As another example, m1 = 0.1m0, that is, when a certain amount of product is produced at the cathode, the positive electrode powder, reducing agent and sulfuric acid are added.

[0082] In this method, the amount of added positive electrode powder and reducing agent is the same as described above, and will not be repeated here. The amount of added sulfuric acid is described below.

[0083] In some embodiments of this application, the total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7. The number of moles of added sulfuric acid is expressed as the number of moles of "H2SO4".

[0084] Surprisingly, with this process, the amount of sulfuric acid added only needs to meet the requirements of the first metallic element, without the need for large amounts of sulfuric acid.

[0085] Specifically, when the reducing agent does not contain sulfur (S), i.e., the reducing agent is selected from hydrogen peroxide, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and the reducing agent. This satisfies 0.9×(0.5N5+0.5N7)≤N6≤1.1×(0.5N5+0.5N7). For example, N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, and N7 to satisfy the above relationship, the solid content W2 of the slurry is maintained within the range of 1 g / L to 50 g / L and the pH is maintained within the range of 2 to 6.5 during the electrolysis process, so as to ensure that the electrolysis process can continue.

[0086] Specifically, when the reducing agent contains sulfur (S), meaning the reducing agent is selected from one or more of sodium sulfite, sodium thiosulfate, and sodium metabisulfite, the amount of sulfuric acid added is determined based on the amount of the first metallic element in the added positive electrode powder and the reducing agent, as well as the amount of sulfur in the reducing agent. The number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9 × (0.5N5 + 0.5N7) ≤ N8 + N6 ≤ 1.1 × (0.5N5 + 0.5N7). For example, N8+N6 can be 0.9×(0.5N5+0.5N7), 0.92×(0.5N5+0.5N7), 0.94×(0.5N5+0.5N7), 0.95×(0.5N5+0.5N7), 0.96×(0.5N5+0.5N7), 0.98×(0.5N5+0.5N7), 1×(0.5N5+0.5N7), 1.02×(0.5N5+0.5N7), 1.04×(0.5N5+0.5N7), 1.06×(0.5N5+0.5N7), 1.08×(0.5N5+0.5N7), or 1.1×(0.5N5+0.5N7), or any two of the above numbers. By adjusting N5, N6, N7, and N8 to satisfy the above relationship, the solid content W2 of the slurry is maintained within the range of 1 g / L to 50 g / L and the pH is maintained within the range of 2 to 6.5 during the electrolysis process, so as to ensure that the electrolysis process can continue.

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

[0088] In some embodiments of this application, in step (1), the pretreatment includes crushing, screening, and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen. For example, the temperature T3 of the high-temperature treatment can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, or 1000°C, or any two of the above numbers. For example, the time t3 of the high-temperature treatment can be 0.1h, 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h, or any two of the above numbers. The positive current collector and positive electrode material layer of the disassembled positive electrode are separated. The positive electrode material layer is then crushed and sieved to prepare positive electrode material layer powder within a certain particle size range. Subsequently, the positive electrode material layer powder is subjected to high-temperature treatment to remove the conductive agent and binder, thereby obtaining the positive electrode powder. This application does not impose any particular limitation on the particle size of the positive electrode material layer powder, as long as it achieves the purpose of this application. For example, the volume average particle size of the positive electrode material layer powder can be from 10 μm to 300 μm.

[0089] In some embodiments of this application, the electrolyzed slurry is filtered to obtain filter residue (unreacted cathode powder) and a filtrate containing a first metal element. The filtrate is then purified to obtain a salt containing the first metal element. In this application, the electrolyzed slurry can be the slurry discharged during the electrolysis process (i.e., the slurry during electrolysis) or the slurry obtained after the electrolysis process (i.e., the slurry after electrolysis). The salt containing the first metal element obtained by purifying the filtrate can be a lithium salt or a sodium salt, thereby achieving the recovery of the first metal element.

[0090] In some embodiments of this application, the filter residue obtained from filtration is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely reacted / recovered during the electrolytic reaction, and the filter residue may still contain the target metal, i.e., the first metal element and / or the second metal element. Adding the filter residue to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process. Furthermore, during electrolytic treatment, as the electrolytic reaction proceeds, the ion concentration of the first metal element in the liquid phase of the slurry increases, allowing electrolysis to be stopped, or a portion of the electrolyzed slurry can be discharged. If the slurry is discharged, the Ni and / or Co element content in the system will decrease. Therefore, the mother liquor obtained after lithium / sodium extraction from the discharged slurry is added to the slurry for further electrolytic treatment. Since the mother liquor has a high Ni and / or Co element content, adding it to the slurry helps to dynamically maintain the Ni and / or Co element ion concentration in the liquid phase of the slurry within a relatively constant range, thus facilitating the continuous progress of the electrolytic reaction.

[0091] In some embodiments of this application, the first metal element is selected from sodium or lithium. The purification process is concentrated crystallization. The filtrate is concentrated and crystallized to obtain concentrated mother liquor and salt containing the first metal element, that is, sodium salt or lithium salt, thereby realizing the recovery of the first metal element.

[0092] The concentrated mother liquor is added to the slurry for further electrolytic treatment. Typically, the target metal is not completely recovered during the concentration and crystallization process, and the concentrated mother liquor may still contain the target metal, primarily Ni and / or Co. Adding the concentrated mother liquor to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste generated during the recovery process. Furthermore, for continuous electrolysis schemes, the Ni and / or Co elements in the concentrated mother liquor can help maintain the Ni and / or Co ion concentration in the slurry liquid phase within a relatively constant range; therefore, it must be returned to the slurry to ensure the electrolytic reaction can continue uninterrupted.

[0093] In some embodiments of this application, the first metal element is selected from lithium. The purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The carbonizing agent is selected from one or more of sodium carbonate, potassium carbonate, and carbon dioxide. The filtrate is carbonized to obtain a lithium-containing salt, a deposition mother liquor, and optionally a nickel- and / or cobalt-containing salt, thereby achieving lithium recovery. Preferably, the deposition mother liquor and optionally the nickel- and / or cobalt-containing salt are returned to the slurry for further electrolysis to improve the recovery rate of Ni and / or Co.

[0094] For schemes where electrolysis is stopped after a period of time, the filtrate is carbonized and deposited to obtain lithium-containing salts and a mother liquor. The mother liquor is collected and added to the slurry for electrolysis in the next electrolysis process. This not only improves the final recovery rate of the target metal but also reduces liquid waste during the recovery process.

[0095] In continuous electrolysis schemes, when lithium is extracted using carbonization deposition, elements such as nickel and cobalt will also be deposited in solid form (e.g., nickel carbonate, cobalt carbonate), resulting in salts containing nickel and / or cobalt. In this case, the nickel / cobalt carbonate can be returned to the slurry to improve the recovery rate of nickel and cobalt. Furthermore, returning it to the slurry helps to dynamically maintain the concentration of Ni and / or Co ions in the liquid phase of the slurry within a relatively constant range.

[0096] This process uses slurry electrolysis and concentration crystallization or carbonization deposition to separate and extract valuable metals from the cathode materials of spent batteries. The acid generated during slurry electrolysis to separate nickel and cobalt continuously dissolves the cathode powder in the solid phase of the slurry, enriching lithium while separating nickel and cobalt, significantly reducing acid consumption. The resulting lithium-rich filtrate can be purified to obtain high-purity lithium sulfate or lithium carbonate. By adding cathode powder, reducing agent, and optionally sulfuric acid during electrolysis, slurry electrolysis can be carried out continuously, resulting in a high recovery rate of valuable metals. Of course, even for electrolysis termination schemes, the electrolysis process needs to continue for a period of time until the sulfuric acid is depleted or the Li in the slurry is reduced. + Stop when the concentration reaches saturation and electrolysis can no longer proceed.

[0097] The following are some possible implementation methods:

[0098] Method 1: The first metal element is selected from lithium, the reducing agent is selected from sulfur dioxide, the feed is positive electrode powder and sulfur dioxide, the electrolysis is stopped after a period of time, and the slurry after the electrolysis is completed is purified to obtain Li element. The purification treatment can be concentration crystallization or carbonization deposition.

[0099] Method 2: The first metal element is selected from lithium, the reducing agent is selected from sulfur dioxide, the feed is positive electrode powder and sulfur dioxide, part of the electrolytic slurry is discharged to keep the electrolysis running continuously, the discharged electrolytic slurry is purified to obtain Li element, the mother liquor after lithium extraction needs to be returned to the slurry, the lithium extraction process can be concentration crystallization or carbonization deposition, when returning the mother liquor after carbonization deposition it is best to remove the sodium.

[0100] Method 3: The first metal element is selected from lithium, the reducing agent is selected from hydrogen peroxide, the feed is positive electrode powder and hydrogen peroxide, the electrolysis is stopped after a period of time, and the slurry after the electrolysis is completed is purified to obtain Li element. The purification process can be concentrated and crystallized or carbonized and deposited.

[0101] Method 4: The first metal element is selected from lithium, the reducing agent is selected from hydrogen peroxide, and the feed consists of positive electrode powder, hydrogen peroxide and sulfuric acid. Part of the slurry in the electrolysis is discharged to keep the electrolysis running. The discharged slurry in the electrolysis is purified to obtain Li element. The mother liquor after lithium extraction needs to be returned to the slurry. The lithium extraction process can be concentration and crystallization or carbonization deposition. When returning the mother liquor by carbonization deposition, it is best to remove the sodium.

[0102] Method 5: The first metal element is selected from lithium, and the reducing agent is selected from any one of sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The feed is positive electrode powder and the above-mentioned reducing agent. Electrolysis is stopped after a period of time. The slurry after electrolysis is purified to obtain Li element. The lithium extraction process is carbonization deposition.

[0103] Method 6: The first metal element is selected from lithium, and the reducing agent is selected from any one of sodium sulfite, sodium thiosulfate, and sodium metabisulfite. The feed consists of positive electrode powder, the above-mentioned reducing agent, and sulfuric acid. Part of the electrolytic slurry is discharged to keep the electrolysis running continuously. The discharged electrolytic slurry is purified to obtain Li element. The mother liquor after lithium extraction needs to be returned to the slurry. The lithium extraction process is carbonization deposition. When returning the mother liquor, it is best to remove the sodium.

[0104] Of course, for sodium batteries, those skilled in the art can choose similar lithium battery solutions based on the teachings of this application, which will not be elaborated here.

[0105] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and the positive electrode includes one or more of lithium nickel cobalt manganese oxide, lithium nickel oxide, and lithium cobalt oxide.

[0106] In some embodiments of this application, the waste battery is a waste lithium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0107] In some embodiments of this application, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as the reducing agent, undergoes the following dissolution reactions:

[0108] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4+30H2O+10O2;

[0109] Electrolysis reactions include:

[0110] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0111] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0112] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0113] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4;

[0114] The elemental nickel and cobalt generated during electrolysis can act as catalysts, partially decomposing hydrogen peroxide into water and oxygen, specifically: 2H₂O₂ = 2H₂O + O₂; thus, the overall reaction is:

[0115] 10LiNi 0.5 Co0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+10O2.

[0116] As can be seen from the above reaction formula, the cathode powder includes LiNi. 0.5 Co 0.2 Mn 0.3 O2, with H2O2 as a reducing agent, during the dissolution reaction, although Co, Ni, and Mn consume SO4... 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Li consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0117] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and the positive electrode includes one or more of sodium cobalt oxide, sodium nickel oxide, and sodium nickel cobalt manganese oxide.

[0118] In some embodiments of this application, the waste battery is a waste sodium-ion battery, and when the positive electrode contains manganese, the anode product includes manganese dioxide.

[0119] In some embodiments of this application, the positive electrode powder comprises NaNiO2, with sodium metabisulfite (Na2S2O5) as a reducing agent, and its dissolution reaction includes:

[0120] 4NaNiO2+Na2S2O5+5H2SO4=3Na2SO4+5H2O+4NiSO4;

[0121] Electrolysis reactions include:

[0122] 2NiSO4+2H2O=2Ni+2H2SO4+O2;

[0123] The overall reaction is:

[0124] 4NaNiO2+Na2S2O5+H2SO4=4Ni+H2O+2O2+3Na2SO4.

[0125] As can be seen from the above reaction formula, the positive electrode powder includes NaNiO2, and sodium metabisulfite is used as a reducing agent. During the dissolution reaction, Ni consumes SO4. 2- However, sulfuric acid is generated during electrolysis; therefore, in the final overall reaction, only Na consumes SO4. 2- Therefore, the amount of sulfuric acid consumed is greatly reduced throughout the entire recycling process.

[0126] In this process, the continuously added positive electrode powder and sulfuric acid work together through a dissolution reaction and an electrolysis reaction that occurs in the same or connected containers. Specifically, the added positive electrode powder consumes sulfuric acid through a dissolution reaction, allowing the electrolysis reaction to continue within a suitable pH range. The electrolysis reaction also produces sulfuric acid, maintaining the recycling of sulfuric acid while continuously dissolving the newly added positive electrode powder, thus increasing the amount of positive electrode powder processed, reducing the use of sulfuric acid, avoiding the introduction of excess alkaline impurities, and enabling the sustainable recycling of positive electrode materials from waste batteries.

[0127] The recycling method provided in this application uses dissolution, electrolysis, and concentrated crystallization / carbonization deposition to separate, extract, and recover valuable metals, namely the first and second metallic elements, from waste battery cathode powder. Electrolysis separates metals such as nickel and cobalt contained in the initial acidic slurry. Because the sulfuric acid produced by the electrolysis reaction can be used to further dissolve more cathode powder in the slurry, this self-sustaining process reduces the use of sulfuric acid in the extraction process. Furthermore, while extracting metals such as nickel and cobalt from the slurry, the concentration of the first metallic element remaining in the slurry increases, making the extraction of the first metallic element possible and efficient. In addition, the recycling method provided in this application can perform continuous electrolysis (including electrolysis with a pause after a period of time and continuous electrolysis without interruption), because the sulfuric acid produced by electrolysis or the added sulfuric acid can dissolve more cathode powder, thereby improving the recovery rate and production capacity. Therefore, the entire recycling process is simple, economical, and efficient, and reduces environmental impact by reducing the use of acid and alkali, making it an environmentally friendly recycling method.

[0128] Example

[0129] 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.

[0130] Test methods and equipment:

[0131] Purity test:

[0132] Cathode products: Digested with acid and then analyzed by ICP using inductively coupled plasma mass spectrometry (ICP-MS).

[0133] Anode product: determined by potassium permanganate titration using a titrator.

[0134] Lithium sulfate crystals: Impurity elements were determined using ICP, and inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis.

[0135] Test of the nickel-cobalt ratio in cathode products:

[0136] The nickel-cobalt ratio of the sample was determined by ICP after acid digestion.

[0137] The methods used in this application are conventional testing methods in the art, and those skilled in the art can choose appropriate testing methods as needed. This application does not impose any limitations.

[0138] Example 1 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishment of hydrogen peroxide + positive electrode powder; not continuous)

[0139] Figure 1 The experimental flowchart for Example 1 is shown below, with the specific steps as follows:

[0140] (1) Disassemble the waste ternary 523 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder by stirring at T3 = 500℃ to remove the residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The stirring time is t3 = 1.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0141] (2) 1000g of positive electrode powder was added to 1475g of sulfuric acid solution (98% by mass). At the same time, 8000mL of 8% hydrogen peroxide was continuously stirred into the slurry at T1=80℃ and added dropwise as a reducing agent to form a slurry. The dissolution reaction time was t1=0.5h. The resulting slurry had a pH=5 and a solid content W1=5g / L. Among them, the total mass of nickel and cobalt in 1000g of positive electrode powder was m0=400g.

[0142] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 80℃. The voltage during the electrolysis process was 3.0V, corresponding to a current density of 20mA / cm². 2 During electrolysis, cathode powder and hydrogen peroxide are continuously added according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 4g of nickel-cobalt metal produced (m1), 10g of cathode powder (the nickel-cobalt content in the cathode powder of ternary 523 lithium-ion batteries is approximately 40wt%) and 80mL of 8% hydrogen peroxide are added. The dissolution reactions in the slurry include:

[0143] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+15H2SO4+15H2O2=5Li2SO4+5NiSO4+2CoSO4+3MnSO4

[0144] +30H2O+10O2

[0145] Electrolysis reactions include:

[0146] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0147] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0148] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0149] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0150] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into lithium sulfate after electrolysis. Specifically, in this embodiment, electrolysis is stopped when the total concentration of nickel and cobalt ions in the slurry is less than 0.05 wt%. The overall reaction is as follows:

[0151] 10LiNi 0.5 Co 0.2 Mn 0.3 O2+5H2SO4+11H2O2=5Li2SO4+5Ni+2Co+3MnO2+16H2O+

[0152] 10O2.

[0153] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 5:2 and a purity of 99.8%. The anode product is manganese dioxide with a purity of 93.5%. The electrolyzed slurry (i.e., the slurry after electrolysis) is filtered to obtain filter residue (unreacted cathode powder) and a lithium-containing filtrate. Excess sodium carbonate is added to the lithium-containing filtrate to precipitate lithium, yielding lithium carbonate crystals with a purity of 99.5%.

[0154] In this embodiment, it can be seen from the overall reaction that the overall system consumes H2SO4, which acts as a sulfur source and H2O2 as a reducing agent. The sulfur in H2SO4 is matched with the lithium in the cathode powder in a 1:2 molar ratio to form Li2SO4, that is, only the sulfur that combines with Li is needed, and the sulfur that combines with Co and Ni is not needed, thus reducing the amount of sulfur used. After sufficient electrolysis by feeding, electrolysis is stopped when the total concentration of nickel and cobalt ions is low, and the corresponding sulfuric acid also tends to be exhausted. Then, the slurry after electrolysis is treated by lithium carbide precipitation to obtain high-purity Li2CO3 crystals.

[0155] Example 2 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: SO2 + positive electrode powder added, not continuous)

[0156] Figure 2 The experimental flowchart for Example 2 is shown below, with specific steps as follows:

[0157] (1) Disassemble the waste lithium cobalt oxide batteries, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 550℃ by introducing air to remove residual conductive agent and binder (some conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0158] (2) 5500g of positive electrode powder was added to a solution prepared by mixing 5050g of sulfuric acid solution (98% mass concentration) and 8L of purified water. Simultaneously, the mixture was continuously stirred at T1 = 90℃, and sulfur dioxide gas (flow rate 1800g / h) was introduced into the bottom of the slurry as a reducing agent to form a slurry. The dissolution reaction time was t1 = 1h. The resulting slurry had a pH of 3 and a solid content of W1 = 50g / L. The total mass of cobalt in the 5500g of positive electrode powder was m0 = 3300g.

[0159] (3) Using a titanium-based iridium-tantalum plate as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 4.0V, corresponding to a current density of 30mA / cm². 2 During electrolysis, positive electrode powder is continuously added and sulfur dioxide gas is introduced according to the electrolysis capacity and the amount of cathode material produced. Specifically, for every 1g of cobalt metal produced (m1), 1.67g of positive electrode powder (the cobalt content in the positive electrode powder of lithium cobalt oxide batteries is approximately 60wt%) is added and 0.7g of SO2 is introduced. The dissolution reactions in the slurry include:

[0160] 2LiCoO2+2H2SO4+SO2=Li2SO4+2CoSO4+2H2O

[0161] Electrolysis reactions include:

[0162] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0163] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration in the slurry reaches 330 g / L (close to the saturation concentration of Li2SO4 in the slurry), electrolysis is stopped. The overall reaction is as follows:

[0164] 2LiCoO2 + SO2 = Li2SO4 + 2Co + O2

[0165] The cathode plate yields cobalt metal with a purity of 99.8%. After filtration and electrolysis, the slurry yields filter residue (unreacted cathode powder) and a lithium-rich filtrate. The lithium-rich filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The concentrated mother liquor can be returned to the slurry for the next electrolysis, resulting in lithium sulfate crystals with a purity of 99.7%. The unreacted cathode powder can also be returned to the slurry for the next electrolysis.

[0166] In this embodiment, the entire system does not consume H2SO4. SO2 acts as both a sulfur source and a reducing agent. The sulfur in SO2 is matched with the lithium in the cathode powder in a 1:2 molar equivalent ratio to form Li2SO4. That is, only the amount of sulfur that combines with Li is needed, and the amount of sulfur that combines with Co is not needed, thus reducing the amount of sulfur used. During the electrolysis process, the concentration of Li+ in the slurry continuously increases. Electrolysis can be stopped when the concentration of Li+ approaches or reaches the saturation concentration. Afterward, the slurry after electrolysis is treated by evaporation and concentration to obtain high-purity Li2SO4.

[0167] Example 3 (Dissolution process: sulfuric acid + positive electrode powder + SO2; Electrolysis process: replenish SO2 + positive electrode powder; continuous operation)

[0168] Figure 3 The experimental flowchart for Example 3 is as follows:

[0169] This embodiment is similar to Embodiment 2, except that the electrolysis does not terminate and can continue, as detailed below:

[0170] Steps (1) to (3) are the same as in Example 2, and step (4) is as follows:

[0171] (4) When the lithium sulfate concentration in the electrolytic slurry (i.e., the slurry in the electrolysis process) reaches 280 g / L, 20% of the volume fraction of the slurry in the electrolysis process is discharged, and the remaining slurry continues to undergo dissolution and electrolysis reactions.

[0172] The cathode plate yields cobalt metal with a purity of 99.85%. The filtered electrolytically treated slurry yields filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue is added to the continuously electrolytically treated slurry. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.7%. The concentrated mother liquor is returned to the continuously electrolytically treated slurry to maintain a dynamic equilibrium of the Co ion concentration in the slurry.

[0173] Example 4 (Dissolution process: sulfuric acid + positive electrode powder + sodium sulfite; Electrolysis process: sodium sulfite + positive electrode powder added; process is not continuous)

[0174] (1) Disassemble the waste sodium nickelate battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder with air at T3 = 600℃ to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 0.5h. Then pass it through a 100-mesh sieve to obtain positive electrode powder.

[0175] (2) 220g of positive electrode powder was added to a solution prepared with 260g of sulfuric acid solution (98% mass concentration) and 0.8L of purified water, and purified water was continued to be added until the slurry volume reached 1.0L. Simultaneously, sodium sulfite was continuously added to the slurry as a reducing agent at T1 = 80℃ with continuous stirring to form a slurry. The dissolution reaction time was t1 = 0.5h. The resulting slurry had a pH of 5 and a solid content of W1 = 20g / L. The total mass of nickel in the 220g of positive electrode powder was m0 = 110g.

[0176] (3) Using graphite as the anode plate and 304 stainless steel as the cathode plate, the slurry was electrolyzed at T2 = 90℃. The voltage during the electrolysis process was 2.0V, corresponding to a current density of 35mA / cm². 2 During electrolysis, positive electrode powder and sodium sulfite are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 10g of nickel metal produced (m1), 20g of positive electrode powder (the nickel content in the positive electrode powder of sodium nickelate batteries is approximately 50%) is added, and 11g of sodium sulfite is introduced. The dissolution reactions in the slurry include:

[0177] 2NaNiO2+Na2SO3+3H2SO4=2Na2SO4+3H2O+2NiSO4

[0178] Electrolysis reactions include:

[0179] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0180] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry until most of the sulfuric acid in the slurry is converted into sodium sulfate after electrolysis. In this embodiment, electrolysis is stopped when the sodium sulfate concentration in the slurry reaches 320 g / L. The overall reaction is as follows:

[0181] 2NaNiO2+Na2SO3+H2SO4=2Ni+H2O+O2+2Na2SO4

[0182] The cathode plate yields nickel metal with a purity of 99.5%. After filtration and cessation of electrolysis, the electrolyzed slurry yields filter residue and a sodium-containing filtrate. The sodium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain sodium sulfate crystals and a concentrated mother liquor; the sodium sulfate crystals have a purity of 99.5%.

[0183] Example 5 (Dissolution process: sulfuric acid + positive electrode powder + hydrogen peroxide; Electrolysis process: replenishing hydrogen peroxide + positive electrode powder + sulfuric acid, continuous process)

[0184] Figure 4 The experimental flowchart for Example 5 is shown below, with the specific steps as follows:

[0185] (1) Disassemble the waste ternary 811 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 550℃ by introducing air to remove the residual conductive agent and binder (some of the conductive agent and binder volatilize in the form of carbon dioxide). The pre-treatment time is t3 = 1h. Then, pass it through a 150-mesh sieve to obtain positive electrode powder.

[0186] (2) 500g of positive electrode powder was added to 750g of sulfuric acid solution (98% by mass). Simultaneously, at T1 = 50℃, 4500mL of 8% hydrogen peroxide was continuously stirred and added dropwise as a reducing agent to form a slurry. The slurry volume was adjusted to 6.2L using purified water. The dissolution reaction time was t1 = 1.5h. The resulting slurry had a pH of 6 and a solid content of W1 = 2g / L. The total mass of nickel and cobalt in the 500g of positive electrode powder was m0 = 272g.

[0187] (3) Using titanium-platinum electrodes as the anode and cathode plates, the slurry was electrolyzed at T2 = 50℃. The voltage during the electrolysis process was 2.5V, corresponding to a current density of 20mA / cm². 2 During electrolysis, cathode powder, hydrogen peroxide, and sulfuric acid are continuously added according to the electrolysis capacity and the amount of material produced at the cathode. Specifically, for every 5g of nickel-cobalt metal produced (m1), 9.2g of cathode powder, 100mL of 8% hydrogen peroxide, and 4.73g of 98wt% H2SO4 are added. The dissolution reactions in the slurry include:

[0188] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+15H2SO4+15H2O2=5Li2SO4+8NiSO4+CoSO4+MnSO4

[0189] +30H2O+10O2

[0190] Electrolysis reactions include:

[0191] 2NiSO4 + 2H2O = 2Ni + 2H2SO4 + O2

[0192] 2CoSO4 + 2H2O = 2Co + 2H2SO4 + O2

[0193] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0194] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0195] (4) The sulfuric acid produced by the electrolysis reaction can continuously dissolve the solid materials in the slurry. When the lithium sulfate concentration reaches 300 g / L, 20% of the liquid phase of the electrolyzed slurry (i.e., the slurry in the electrolysis process) is discharged. The remaining slurry continues to undergo dissolution and electrolysis reactions. The overall reaction is:

[0196] 10LiNi 0.8 Co 0.1 Mn 0.1 O2+5H2SO4+7H2O2=5Li2SO4+8Ni+Co+MnO2+12H2O+10O2

[0197] After electrolysis, the cathode product is nickel-cobalt metal with a nickel-cobalt molar ratio of 8:1 and a purity of 99.75%. The anode product is manganese dioxide with a purity of 93.3%. The filtered electrolytic slurry yields filter residue (unreacted cathode powder) and a lithium-containing filtrate. The filter residue is added to the slurry undergoing continuous electrolysis. The lithium-containing filtrate is evaporated, concentrated, cooled, crystallized, and filtered to obtain lithium sulfate crystals and a concentrated mother liquor. The lithium sulfate crystals have a purity of 99.85%. The concentrated mother liquor is returned to the slurry undergoing continuous electrolysis to maintain a dynamic balance of Co / Ni ion concentration in the slurry.

[0198] Comparative Example 1

[0199] (1) Disassemble the waste ternary 622 lithium-ion battery, scrape off the positive electrode material layer obtained from the disassembly, and then crush and sieve it to obtain positive electrode material layer powder. Pre-treat the positive electrode material layer powder in a rotary kiln at T3 = 650℃ by introducing air to remove residual conductive agent and binder. The pre-treatment time is t3 = 2h. Then, pass it through a 100-mesh sieve to obtain positive electrode powder.

[0200] (2) 300g of positive electrode powder was added to 400g of sulfuric acid solution (mass concentration 98%). At the same time, the volume of the slurry was adjusted to 3L with pure water at T1=50℃ to form a slurry. The dissolution reaction time was t1=1h. The pH of the obtained slurry was 2 and the solid content was W1=0.1g / L.

[0201] (3) Using stainless steel as the cathode plate and lead-calcium alloy as the anode plate, the slurry was electrolyzed at T2 = 60℃. The voltage during electrolysis was 2.5V, corresponding to a current density of 15mA / cm². 2 .

[0202] After about 15 minutes of electrolysis, the pH of the slurry dropped to 1, and obvious bubbles were generated on the cathode plate. This was because there was too little positive electrode powder in the slurry, which could not neutralize the acid produced by electrolysis, thus preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0203] In the recovery method described in this application, SO2 in Example 2 simultaneously acts as both a sulfur source and a reducing agent. The sulfur in SO2 or sulfuric acid is matched with Li or Na in the positive electrode powder in a 1:2 molar equivalent ratio to form Li2SO4 or Na2SO4. That is, only the amount of sulfur required to combine with Li or Na is needed, and the amount of sulfur required to combine with Co, Ni, or Mn is not needed. Therefore, the amount of sulfur used is reduced, which also reduces the amount of sulfuric acid used, thereby reducing the recovery cost.

[0204] Li in the slurry during electrolysis + As the concentration increases, it can be achieved in Li + Electrolysis is stopped when the concentration approaches or reaches saturation, as in Example 2; alternatively, positive electrode powder and reducing agent can be continuously added for continuous electrolysis, as in Example 3; or positive electrode powder, reducing agent, and sulfuric acid can be continuously added for continuous electrolysis, as in Example 5. The electrolyzed slurry is then treated by evaporation concentration or carbonization deposition to obtain high-purity Li₂SO₄. This achieves the recovery of Li, Na, Co, Ni, and Mn elements, and the recovered product has high purity. In contrast, in Comparative Example 1, due to insufficient positive electrode powder in the slurry during electrolysis, the acid generated during electrolysis could not be neutralized, leading to the generation of hydrogen gas, which prevented the electrolysis process from proceeding normally, resulting in a product with low purity.

[0205] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for recycling the positive electrode of a waste battery, comprising the following steps: (1) Disassemble waste batteries to obtain positive electrodes, and pre-treat the positive electrodes to obtain positive electrode powder; (2) The positive electrode powder, sulfuric acid, reducing agent and water are mixed and dissolved to obtain a slurry, the slurry containing a solid phase and a liquid phase, the solid phase including the positive electrode powder that has not undergone the dissolution reaction; (3) Electrolyze the slurry, and during the electrolysis process, add at least the positive electrode powder and the reducing agent to the slurry; The electrolytic treatment produces sulfuric acid, which then undergoes a dissolution reaction with the added positive electrode powder and the reducing agent. (4) The electrolytic treatment yields an anode product, a cathode product, and an electrolytically treated slurry. The cathode products include nickel and / or cobalt; In step (2), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH of the slurry is 2 to 6.5; the reducing agent is selected from one or more of hydrogen peroxide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, and sulfur dioxide. In step (3), the addition of at least the positive electrode powder and the reducing agent to the slurry includes: adding the positive electrode powder and the reducing agent to the slurry, or adding the positive electrode powder, the reducing agent and sulfuric acid to the slurry, so that the solid content W2 of the slurry is maintained in the range of 1 g / L to 50 g / L, and the pH of the slurry is maintained in the range of 2 to 6.5; When the mass of nickel and / or cobalt added to the cathode product is m1, at least the cathode powder and the reducing agent shall be added, m1≤0.1m0, where m0 is the mass of nickel and / or cobalt in the cathode powder added in step (2); The positive electrode powder includes a first metal element and a second metal element, wherein the first metal element is selected from lithium or sodium, and the second metal element is selected from at least one of nickel, cobalt, and manganese. The total number of moles of nickel and / or cobalt added to the cathode product is N1, and the total number of moles of nickel and / or cobalt added to the cathode powder is N2, where 0.95N1≤N2≤1.05N1; the total number of moles of the second metal element added to the cathode powder is N3, and the total number of moles of the added reducing agent is N4, where 0.25N3≤N4≤3N3.

2. The recycling method according to claim 1, wherein, In step (2), the conditions for the dissolution reaction are: temperature T1 is 40℃ to 95℃; time t1 is 0.1h to 2h.

3. The recycling method according to claim 2, wherein, In step (2), the solid content W1 of the slurry is 2 g / L to 50 g / L and the pH is 3 to 6; In step (3), at least the positive electrode powder and the reducing agent are added to maintain the solid content W2 of the slurry in the range of 2 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6; the temperature T2 of the electrolysis treatment is 20°C to 95°C and the voltage is 2.5V to 4.5V.

4. The recycling method according to claim 1, wherein, 0.0001m0≤m1≤0.1m0.

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

6. The recycling method according to claim 5, wherein, The total number of moles of the first metal element in the added positive electrode powder is N5, the total number of moles of the added sulfuric acid is N6, and the total number of moles of the first metal element in the added reducing agent is N7. Wherein, when the reducing agent does not contain sulfur, the following condition is satisfied: 0.9 × (0.5N5 + 0.5N7) ≤ N6 ≤ 1.1 × (0.5N5 + 0.5N7); or, When the reducing agent contains sulfur, the number of moles of sulfur in the added reducing agent is N8, satisfying the following formula: 0.9×(0.5N5+0.5N7)≤N8+N6≤1.1×(0.5N5+0.5N7); The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

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

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

9. The recycling method according to claim 1, wherein, The electrolyzed slurry is filtered to obtain filter residue and filtrate containing the first metal element. The filtrate is then purified to obtain a salt containing the first metal element.

10. The recycling method according to claim 9, wherein, The filter residue is added to the slurry for further electrolytic treatment.

11. The recycling method according to claim 9, wherein, The first metal element is selected from sodium or lithium, the purification process is concentration and crystallization, and the filtrate is concentrated and crystallized to obtain concentrated mother liquor and the salt containing the first metal element.

12. The recycling method according to claim 11, wherein, The concentrated mother liquor is added to the slurry for further electrolysis.

13. The recycling method according to claim 9, wherein, The first metal element is selected from lithium, and the purification process involves adding a carbonizing agent to the filtrate for carbonization deposition. The filtrate, after carbonization deposition, yields at least a lithium-containing salt and a mother liquor.

14. The recycling method according to claim 13, wherein, The sedimentation mother liquor is added to the slurry for further electrolytic treatment.

15. The recycling method according to claim 1, wherein, In step (1), the pretreatment includes crushing, screening and high-temperature treatment. The temperature T3 of the high-temperature treatment is 300°C to 1000°C, the time t3 is 0.1h to 10h, and the atmosphere is selected from air or oxygen.

16. The recycling method according to claim 15, wherein, In step (3), the anode and cathode in the electrolytic treatment are each independently selected from graphite or inert metal electrodes, and the inert metal electrode is selected from one of platinum electrode, lead-silver alloy electrode, lead-calcium alloy electrode, titanium electrode, and titanium alloy electrode.

17. The recycling method according to claim 15, wherein, In step (4), the anode product includes manganese dioxide.

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