Method for recovering positive electrode of waste battery

Abstract

In the recycling method provided in the application, the positive electrode powder and the reducing agent are subjected to heat treatment, carbon in the positive electrode powder can be removed, and nickel-cobalt-manganese therein can be reduced, then most of lithium and nickel-cobalt-manganese therein are separated by pickling, and the obtained solid filter material mainly comprises nickel-cobalt-manganese metals and oxides thereof. Then, the solid filter material is subjected to dissolution and electrolysis by sulfuric acid, and compared with a traditional process, the consumption of sulfuric acid is greatly reduced in the electrolysis process, and the treatment process is simple, and the recycling economic benefit is high.

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. Among these, batteries using ternary materials as the positive electrode active material are particularly widely used.

[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, 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

[0004] 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:

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

[0007] (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).

[0008] 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;

[0009] (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.

[0010] (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.

[0011] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0012] 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).

[0013] In some embodiments of this application, in step (2), the heat treatment time t1 is 1h to 3h.

[0014] In some embodiments of this application, in step (2), the acid is selected from sulfuric acid.

[0015] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 95% to 99%.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] In some embodiments of this application, in step (4), the solid filter material is added to the slurry during the electrolysis process.

[0022] 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.

[0023] 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.

[0024] 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).

[0025] In some embodiments of this application, 0.0001m0 ≤ m1 ≤ 0.1m0.

[0026] 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.

[0027] 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.

[0028] In some embodiments of this application, the electrolysis process is stopped when a preset condition is met, and the preset condition is any one of the following:

[0029] (1) The pH of the electrolyzed slurry is less than or equal to 3;

[0030] (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%.

[0031] 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.

[0032] 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.

[0033] In some embodiments of this application, in step (4), the anode product includes either manganese dioxide or oxygen.

[0034] The beneficial effects of this application are:

[0035] 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.

[0036] 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

[0037] 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.

[0038] Figure 1 The XRD pattern of the material after reduction and calcination in Example 1;

[0039] Figure 2 This is the experimental flowchart for Example 1. Detailed Implementation

[0040] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and 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.

[0041] 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.

[0042] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0043] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0044] (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.

[0045] 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;

[0046] (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.

[0047] (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.

[0048] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0049] In some embodiments of this application, in step (2), the washing is acid washing.

[0050] 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.

[0051] This application also provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0052] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0053] (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).

[0054] Solid filter media include elemental Me and oxide MeO, wherein Me is selected from at least one of the elements Ni, Co, and Mn;

[0055] (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.

[0056] (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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] In this application, when the reducing agent is selected from CO, the heat treatment in step (2) includes the following reaction:

[0066] 2CO+2LiMeO2=Li2CO3+Me+MeO+CO2↑;

[0067] CO2 + C = 2CO↑.

[0068] In this application, the dissolution reaction in step (3) includes the following reactions:

[0069] Me + H₂SO₄ = H₂ + MeSO₄;

[0070] MeO + H2SO4 = H2O + MeSO4.

[0071] 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:

[0072] 2NiSO4+2H2O=2Ni+2H2SO4+O2↑

[0073] 2CoSO4+2H2O=2Co+2H2SO4+O2↑

[0074] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0075] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0076] 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 states, while Mn element mainly exists in the oxide state of MnO.

[0077] Dissolution reactions include:

[0078] 8Ni+Co+MnO+10H2SO4=8NiSO4+CoSO4+MnSO4+H2O+9H2↑

[0079] The electrolysis reaction is as follows:

[0080] 8NiSO4+CoSO4+MnSO4+10H2O=8Ni+Co+MnO2+10H2SO4+4O2↑;

[0081] 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:

[0082] 8Ni+Co+MnO+9H2O=8Ni+Co+MnO2+9H2↑+4O2↑.

[0083] 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.

[0084] 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.

[0085] 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;

[0086] 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 reactions:

[0087] 2CoSO4+2H2O=2Co+2H2SO4+O2↑;

[0088] The overall reaction equation is:

[0089] 2CoO=Co+O2↑;

[0090] 2Co + 2H₂O = 2Co + 2H₂↑ + O₂↑

[0091] In some embodiments of this application, the waste battery is a waste ternary nickel-cobalt-manganese battery, and the anode product includes manganese dioxide.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[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. 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.

[0103] 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.

[0104] 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. + The accumulation of buildup can hinder the normal operation of the electrolytic process.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] In some embodiments of this application, in step (4), the anode product includes either manganese dioxide or oxygen.

[0113] 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.

[0114] Example

[0115] 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.

[0116] Test methods and equipment:

[0117] Purity test:

[0118] 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%".

[0119] Calculation of elution rate:

[0120] The Li content in the cathode powder and the Li content in the washed solid filter media were determined by ICP. The Li elution rate was calculated as (1 - Li content in the washed solid filter media / Li content in the cathode powder) × 100%.

[0121] The elution rates of other elements can be calculated similarly.

[0122] X-ray diffraction (XRD) test:

[0123] 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.

[0124] Preparation of positive electrode powder:

[0125] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn 0.1The 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%.

[0126] Unless otherwise specified, the following examples and comparative examples all use the positive electrode powder prepared as described above.

[0127] Example 1

[0128] Figure 2 The experimental flowchart for Example 1 is shown below, with the specific steps as follows:

[0129] 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 material was removed and subjected to XRD testing. The test results are shown in [Figure number missing]. Figure 1 This indicates that the nickel, cobalt, and manganese elements in the calcined material were completely reduced. Acid washing was then performed using a sulfuric acid aqueous solution. The concentration of the sulfuric acid aqueous solution was 4.88 mol / L, and the volume was 150 ml. The molar ratio X of lithium in the cathode powder to hydrogen in the sulfuric acid during washing was approximately 1:1.46. After filtration, solid filter media and lithium-containing filtrate were obtained. The ICP data of the obtained solid filter media (Me / MeO) are shown in Table 1. Table 1 shows that the elution rate of Li was approximately 96.3%, which facilitates subsequent dissolution and electrolysis reactions.

[0130] 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%.

[0131] Table 1

[0132]

[0133]

[0134] Example 2

[0135] 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.

[0136] 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%.

[0137] Examples 3 to 11

[0138] Except for adjusting the relevant preparation parameters according to Table 2, the rest is the same as in Example 1. In Examples 9 to 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, i.e., the reduction calcination process, nitrogen gas is continuously introduced.

[0139] Comparative Examples 1 to 5

[0140] Except for adjusting the relevant preparation parameters according to Table 2, everything else is the same as in Example 1. Specifically:

[0141] Comparative Example 1

[0142] 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%.

[0143] 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.

[0144] Comparative Example 2

[0145] 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.

[0146] Comparative Example 3

[0147] 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.

[0148] Compared with Example 1, Comparative Example 3 shows 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.

[0149] Comparative Example 4

[0150] 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.

[0151] 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.

[0152] Comparative Example 5

[0153] Similar to Example 1, the difference is that the material after reduction roasting is washed with water, as follows:

[0154] 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%.

[0155] 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.

[0156] The preparation parameters and test data of each embodiment and comparative example are shown in Table 2.

[0157] Table 2

[0158]

[0159]

[0160] Note: " / " in Table 2 indicates that there are no corresponding preparation parameters or performance data; since the elution rate of Li in the lithium filtrate of Comparative Examples 1 to 5 was low, the purity of the cathode products was not tested.

[0161] Referring to Table 2, from Examples 1 to 11, and Comparative Examples 1 to 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 electrolysis process, the consumption of sulfuric acid is greatly reduced compared with the traditional process. Therefore, the recovery is economically efficient.

[0162] 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.

[0163] 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 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.

2. The recycling method according to claim 1, 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%.

3. The recycling method according to claim 1, 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.

4. The recycling method according to claim 1, 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.

5. The recycling method according to claim 4, 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).

6. The recycling method according to claim 5, 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.

7. The recycling method according to claim 4, 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.

8. The recycling method according to claim 7, 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%.

9. The recycling method according to claim 1, 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.

10. The recycling method according to claim 1, 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.

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