Recovery method of ternary positive electrode material

Abstract

The invention discloses a recovery method of a ternary positive electrode material, and relates to the technical field of lithium battery recovery, and the recovery method of the ternary positive electrode material comprises the steps that the ternary positive electrode material of a waste battery is placed in a bag type anode frame of an electrolytic bath and electrolyzed, and the bag type anode frame comprises a conductive frame and a filter cloth bag wrapping the conductive frame; collecting the alloy powder deposited on the cathode of the electrolytic bath; and collecting the electrolyzed liquid, and carrying out lithium precipitation on the electrolyzed liquid to obtain the lithium salt. The recovery cost of the ternary positive electrode material is effectively reduced, and the recovery rate is improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium battery recycling, and in particular to a method for recycling ternary positive electrode materials. Background Art

[0002] With the rapid development of mobile electronic products and new energy vehicle industries, the production and application of lithium batteries as their core power source have increased dramatically. However, the limited service life of lithium batteries has led to a surge in the number of waste lithium batteries, which will pose a serious threat to the environment if not properly handled. The positive electrode materials in waste lithium batteries, especially ternary materials such as lithium cobalt oxide, manganese cobalt oxide and nickel manganese cobalt oxide, are rich in transition metal elements such as cobalt, nickel, manganese and lithium, and have extremely high recycling value.

[0003] Hydrometallurgy is the mainstream method for recycling waste lithium batteries, mainly including the combined fire-wet method for preferential lithium extraction technology and the full wet leaching technology. Although the two methods have different technical paths, they both involve the reduction of high-priced metals and the subsequent metal recovery process in the acid solution system, which inevitably introduces a large amount of acid, alkali and reducing agent, resulting in high recycling costs.

[0004] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of this application is to provide a method for recycling ternary positive electrode materials, aiming to reduce the recycling cost of ternary positive electrode materials and improve the recovery rate.

[0006] To achieve the above-mentioned purpose, the present application proposes a method for recycling ternary positive electrode materials, the method comprising: Placing the ternary positive electrode material of the waste battery in a bag-type anode frame of an electrolytic cell and performing electrolysis, wherein the bag-type anode frame comprises a conductive frame and a filter bag wrapped around the conductive frame; collecting alloy powder deposited on the cathode of the electrolytic cell; The post-electrolysis liquid is collected, and lithium is precipitated from the post-electrolysis liquid to obtain lithium salt.

[0007] In one embodiment, the electrolysis voltage of the electrolytic cell is 3.5-6.5 V, and the current density is 500-800 mA / cm2.

[0008] In one embodiment, the electrolysis temperature of the electrolytic cell is 40-50°C.

[0009] In one embodiment, the hydrogen ion concentration of the electrolyte in the electrolytic cell is: 0.1~2.5 mol / L; And / or, the electrolyte in the electrolytic cell includes: sulfuric acid and / or sodium sulfate.

[0010] In one embodiment, after the step of collecting the alloy powder deposited on the cathode of the electrolytic cell, the method further comprises: Performing ammonia leaching on the alloy powder to obtain a precipitate and a first filtrate; Distilling ammonia from the first filtrate to obtain a mixed hydroxide; acid leaching the precipitate to obtain a second filtrate; The pH of the second filtrate is adjusted to obtain manganese hydroxide.

[0011] In one embodiment, the leaching agent used in the ammonia leaching includes: ammonium sulfate and ammonia water; The mass ratio of the ammonium sulfate to the ammonia water is (0.5-1):2, and the concentration of the ammonia water is 1-5 mol / L.

[0012] In one embodiment, after the step of obtaining the lithium salt, the method further comprises: ball-milling the mixed hydroxide, the lithium salt and the manganese hydroxide to obtain a mixed powder; The mixed powder is calcined to obtain positive electrode powder.

[0013] In one embodiment, the calcination temperature is 750-1000°C.

[0014] In one embodiment, the step of mixing and ball-milling the mixed hydroxide, the lithium salt and the manganese hydroxide to obtain a mixed powder comprises: A metal source is added to adjust the metal component, wherein the mass ratio of the metals in the mixed powder is Li:Ni:Co:Mn=(1~1.02):(0.5~0.65):(0.2~0.25):(0.2~0.35).

[0015] In one embodiment, the step of precipitating lithium on the electrolyte comprises: Adjusting the pH of the electrolyzed solution to 3.8-4.5 and removing impurities at one time; The pH of the post-electrolysis solution is adjusted to 9.5-10, and impurities are removed for a second time.

[0016] One or more technical solutions proposed in this application have at least the following technical effects: by placing the ternary positive electrode material of the waste battery in the bag-type anode frame of the electrolytic cell and performing electrolysis, wherein the bag-type anode frame includes a conductive frame and a filter bag wrapped with the conductive frame; then collecting the alloy powder deposited on the cathode of the electrolytic cell to achieve the recovery of metals such as nickel, cobalt, and manganese in the ternary positive electrode material; then collecting the post-electrolysis liquid, and precipitating lithium in the post-electrolysis liquid to obtain lithium salt, thereby achieving lithium recovery. The embodiment of this application uses electrolysis technology and the discharge characteristics of elements to achieve efficient and clean separation of target metal elements. The method introduces fewer types of chemical agents, has low impurity elements, high recovery efficiency, and low recovery cost, thereby achieving green and efficient reuse of ternary battery pole piece powder. At the same time, by using a bag-type anode frame during the electrolysis process, the solid byproducts (such as oxides or precipitates) generated by the ternary positive electrode material of the anode during the electrolysis process can be effectively prevented from directly entering the electrolyte, thereby avoiding contamination of the post-electrolysis liquid, reducing the difficulty and cost of subsequent treatment, and improving the purity of the recovered product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A schematic diagram of a process flow diagram provided for the first embodiment of the method for recycling ternary cathode materials of the present application; Figure 2 This is a flow chart of a relatively complete embodiment of the method for recycling ternary positive electrode materials of the present application.

[0020] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0022] Hereinafter, the embodiment of the method for recycling the ternary positive electrode material of the present application is specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0023] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0025] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0026] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0027] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0028] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and understandable, the technical solution of the present application is further described below in conjunction with the accompanying drawings and embodiments. However, the present application is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights claimed in the present application.

[0030] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present application. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0031] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0032] In conventional technology, the recycling methods for ternary cathode materials mainly include fire-wet method combined with preferential lithium extraction technology and full wet leaching technology. Although the two methods have different technical paths, they both involve the reduction of high-priced metals and the subsequent metal recovery process in the acid solution system, which inevitably introduces a large amount of acid, alkali and reducing agent, resulting in high recycling costs.

[0033] The present application provides a solution, by placing the ternary positive electrode material of the waste battery in the bag-type anode frame of the electrolytic cell and electrolyzing, wherein the bag-type anode frame includes a conductive frame and a filter bag wrapped with the conductive frame; then collecting the alloy powder deposited on the cathode of the electrolytic cell to achieve the recovery of metals such as nickel, cobalt, and manganese in the ternary positive electrode material; then collecting the post-electrolysis liquid, and precipitating lithium in the post-electrolysis liquid to obtain lithium salt to achieve lithium recovery. The embodiment of the present application uses electrolysis technology and the discharge characteristics of elements to achieve efficient and clean separation of target metal elements. The method introduces fewer types of chemical agents, has low impurity elements, high recovery efficiency, and low recovery cost, and realizes green and efficient reuse of ternary battery pole piece powder. At the same time, by using a bag-type anode frame during the electrolysis process, the solid byproducts (such as oxides or precipitates) generated by the ternary positive electrode material of the anode during the electrolysis process can be effectively prevented from directly entering the electrolyte, thereby avoiding the contamination of the post-electrolysis liquid, reducing the difficulty and cost of subsequent processing, and improving the purity of the recovered product.

[0034] Based on this, the present application embodiment provides a method for recycling ternary positive electrode materials, referring to Figure 1 , Figure 1 This is a schematic diagram of the process of the first embodiment of the method for recycling ternary positive electrode materials of the present application. In this embodiment, the method for recycling ternary positive electrode materials includes: Step S10, placing the ternary positive electrode material of the waste battery in a bag-type anode frame of the electrolytic cell and performing electrolysis, wherein the bag-type anode frame includes a conductive frame and a filter cloth bag wrapped around the conductive frame; In a feasible embodiment, a ternary positive electrode material of waste batteries is provided, and the ternary positive electrode material is placed in a bag-type anode frame of an electrolytic cell for electrolysis, wherein the bag-type anode frame can be composed of a conductive frame and a filter cloth bag wrapping the conductive frame.

[0035] Ternary positive electrode materials generally refer to lithium battery positive electrode materials composed of three elements: nickel (Ni), cobalt (Co), and manganese (Mn). Through electrolysis, under the action of the electric field, the mixed oxide of nickel, cobalt, manganese, and lithium at the anode dissociates into monomer lithium ions, nickel ions, cobalt ions, and manganese ions, and migrates to the cathode under the action of the external electric field; then the nickel ions, cobalt ions, and manganese ions are discharged at the cathode to obtain electrons, forming a cathode alloy, that is, a mixed metal powder of cobalt and nickel (i.e., alloy powder).

[0036] Exemplarily, waste batteries are crushed and sorted to obtain positive electrode materials; the positive electrode materials are then placed in a high-temperature furnace for calcination to remove organic matter and moisture in the positive electrode materials.

[0037] In one feasible embodiment, the electrolysis voltage of the electrolytic cell is: 3.5~6.5 V; for example, the electrolysis voltage of the electrolytic cell is 3.5 V, 3.6 V, 3.8 V, 4 V, 4.2 V, 4.5 V, 4.6 V, 4.8 V, 5 V, 5.2 V, 5.4 V, 5.5 V, 5.6 V, 5.8 V, 6 V, 6.2 V, 6.3 V, 6.4 V, 6.5 V, etc. If the electrolysis voltage is too low, cobalt, nickel, and manganese are difficult to discharge at the cathode, but only form hydroxide precipitation at the cathode as the electrolysis proceeds, but this precipitate hinders electrolysis and there is a great risk of burning the plate. When the voltage is too high, the electrolyte itself may decompose, resulting in reduced stability of the electrolyte. At the same time, the side reaction between the positive electrode material and the electrolyte will intensify, which may cause the transition metal to dissolve, further decompose the electrolyte, produce a large amount of gas, and increase safety risks. Therefore, the electrolysis voltage of the electrolytic cell is determined to be 3.5-6.5 V in the embodiment of the present application.

[0038] Preferably, the electrolysis voltage of the electrolytic cell is 4-4.5 V.

[0039] In one embodiment, the current density of the electrolytic cell is 500-800 mA / cm 2 ; For example, the current density of the electrolytic cell is: 500 mA / cm 2 , 550 mA / cm 2 , 600 mA / cm 2 , 650 mA / cm 2 , 700 mA / cm 2 , 750 mA / cm 2 、800mA / cm 2 The current density determines the shape of the cathode deposit. The larger the current density, the finer the powder, the thicker the deposit, and the higher the yield, but it is also easy to burn the plate. Therefore, the current density of the electrolytic cell is preferably: 500~800 mA / cm 2 .

[0040] In one feasible embodiment, the electrolysis temperature of the electrolytic cell is 40-50°C; for example, the electrolysis temperature of the electrolytic cell is 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, etc. If the temperature is too high, a large amount of electrolyte may evaporate, aggravating equipment corrosion and causing reverse dissolution, resulting in reduced yield. If the temperature is too low, the electrolysis reaction rate may decrease, thereby reducing the production efficiency of the deposited alloy.

[0041] In one feasible embodiment, the hydrogen ion concentration of the electrolyte in the electrolytic cell is 0.1-2.5 mol / L; for example, the hydrogen ion concentration of the electrolyte in the electrolytic cell is 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.5 mol / L, etc. It should be understood that during the electrolysis process, the hydrogen ion concentration of the electrolyte needs to be maintained at 0.1-2.5 mol / L.

[0042] In one feasible embodiment, the electrolyte in the electrolytic cell includes: sulfuric acid and / or sodium sulfate.

[0043] Exemplarily, the salt concentration in the electrolyte is 2-10 wt.%.

[0044] In this embodiment, by maintaining the pH of the electrolyte within an acidic range, the influence of impurity hydrolysis on electrolysis is effectively avoided.

[0045] Step S20, collecting the alloy powder deposited on the cathode of the electrolytic cell; In a feasible embodiment, through electrolysis, the nickel ions, cobalt ions, and manganese ions in the ternary positive electrode material are discharged at the cathode to obtain electrons to form a cathode alloy, that is, a mixed metal powder of cobalt and nickel (that is, alloy powder), wherein the particle size of the alloy powder can be D90<74 μm; further, the particle size of the alloy powder can be D50<10 μm.

[0046] Step S30, collecting the post-electrolysis liquid, and precipitating lithium from the post-electrolysis liquid to obtain lithium salt.

[0047] In a feasible embodiment, since a bag-type anode frame is used during the electrolysis process, it is possible to effectively prevent the solid byproducts (such as oxides or precipitates) generated by the ternary positive electrode material of the anode during the electrolysis process from directly entering the electrolyte, thereby preventing contamination of the post-electrolysis liquid. The post-electrolysis liquid is then collected and lithium is precipitated from the post-electrolysis liquid to obtain lithium salt.

[0048] Exemplarily, the post-electrolysis solution is a lithium-containing solution with a lithium concentration of 4 to 12 g / L.

[0049] In one feasible implementation, step S30 of precipitating lithium in the electrolyte includes: Step S31, adjusting the pH of the electrolyzed solution to 3.8-4.5 and removing impurities at one time; In a feasible embodiment, the pH of the post-electrolysis liquid is adjusted to 3.8-4.5 so that some impurity ions (such as iron, aluminum, etc.) in the post-electrolysis liquid will form insoluble hydroxide precipitates, and a primary impurity removal is performed to remove the formed impurity precipitates to obtain a primary impurity-removed filtrate.

[0050] Step S32, adjusting the pH of the electrolyzed solution to 9.5-10, and performing secondary impurity removal.

[0051] In a feasible embodiment, the pH of the post-electrolysis solution (i.e., the filtrate after the first impurity removal) is further adjusted to 9.5-10 to allow the impurity ions to form a precipitate, and precipitation and filtration operations are performed again to remove the newly formed impurity precipitate to obtain a filtrate after the second impurity removal.

[0052] For example, carbon dioxide can be added to the filtrate after the secondary impurity removal to precipitate lithium to obtain lithium carbonate.

[0053] In one feasible embodiment, after the step of collecting the alloy powder deposited on the cathode of the electrolytic cell in step S20, the method further includes: Step S21, performing ammonia leaching on the alloy powder to obtain a precipitate and a first filtrate; In a feasible embodiment, the alloy powder is mixed with an ammonia leaching agent so that the metal elements (nickel, cobalt) in the alloy powder form corresponding metal ammine complexes or hydroxides with ammonia, thereby dissolving them from the alloy powder; since manganese is difficult to complex with ammonia water, it will be retained in the precipitate, thereby obtaining a precipitate containing manganese and a first filtrate containing nickel and cobalt.

[0054] In one feasible embodiment, the leaching agent used in ammonia leaching includes: ammonium sulfate and ammonia water.

[0055] In one feasible embodiment, the mass ratio between ammonium sulfate and aqueous ammonia is (0.5~1):2; for example, the mass ratio between ammonium sulfate and aqueous ammonia is 0.5:2, 0.6:2, 0.7:2, 0.8:2, 0.9:2, 1:2, etc.

[0056] In one feasible embodiment, the concentration of ammonia water is 1-5 mol / L; for example, the concentration of ammonia water is 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.4 mol / L, 3.6 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.4 mol / L, 4.6 mol / L, 4.8 mol / L, 5 mol / L, etc.

[0057] Step S22, distilling ammonia from the first filtrate to obtain a mixed hydroxide; In a feasible embodiment, the filtrate is heated to volatilize ammonia from the solution, thereby achieving ammonia evaporation and obtaining a mixed hydroxide precipitate containing nickel and cobalt; and the mixed hydroxide can be used for the preparation of battery positive electrode powder.

[0058] Exemplarily, the mixed hydroxide is a mixed powder of cobalt hydroxide and nickel hydroxide, and the ratio thereof is cobalt hydroxide:nickel hydroxide=1:(0.2-0.4).

[0059] For example, the steam produced by ammonia evaporation can be condensed and recovered and reused as a leaching agent for ammonia leaching.

[0060] Step S23, acid leaching the precipitate to obtain a second filtrate; In a feasible embodiment, the precipitate is mixed with an acid leaching agent for acid leaching to dissolve the manganese element in the precipitate to obtain a second filtrate containing manganese.

[0061] Exemplarily, the leaching agent for acid leaching includes at least one of sulfuric acid, hydrochloric acid, and nitric acid.

[0062] Step S24, adjusting the pH of the second filtrate to obtain manganese hydroxide.

[0063] In a feasible embodiment, the pH of the second filtrate is adjusted to 9-12 to obtain a precipitate of manganese hydroxide, wherein the manganese hydroxide can be used for the preparation of battery positive electrode powder.

[0064] In a feasible embodiment, after the step of obtaining the mixed hydroxide in step S30, the method further comprises: Step S33, ball-milling the mixed hydroxide, lithium salt and manganese hydroxide to obtain a mixed powder; Step S34, calcining the mixed powder to obtain positive electrode powder.

[0065] In one feasible embodiment, the mixed hydroxide, manganese hydroxide and lithium salt obtained by liquid precipitation of lithium after electrolysis are mixed and ball-milled to obtain a mixed powder; the mixed powder is then roasted to obtain positive electrode powder, thereby realizing the recycling of ternary positive electrode materials of waste batteries.

[0066] In one feasible implementation manner, the calcination temperature is 750-1000°C; for example, the calcination temperature is 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc.

[0067] In one feasible implementation, step S33, the step of ball-milling the mixed hydroxide, lithium salt and manganese hydroxide to obtain a mixed powder comprises: Step S331, adding a metal source to adjust the metal composition, wherein the mass ratio of the metals in the mixed powder is Li:Ni:Co:Mn=(1~1.02):(0.5~0.65):(0.2~0.25):(0.2~0.35).

[0068] In a feasible embodiment, the metal source adjusts the metal components so that the mass ratio of the metals in the mixed powder is Li:Ni:Co:Mn=(1~1.02):(0.5~0.65):(0.2~0.25):(0.2~0.35).

[0069] In this embodiment, the ternary positive electrode material of the waste battery is placed in a bag-type anode frame of the electrolytic cell and electrolyzed, wherein the bag-type anode frame includes a conductive frame and a filter bag wrapped with the conductive frame; and then the alloy powder deposited on the cathode of the electrolytic cell is collected to realize the recovery of metals such as nickel, cobalt, and manganese in the ternary positive electrode material; and then the post-electrolysis liquid is collected, and lithium is precipitated in the post-electrolysis liquid to obtain lithium salt, thereby realizing the recovery of lithium. The embodiment of the present application realizes the efficient and clean separation of the target metal element by electrolysis technology and the discharge characteristics of the element. The method introduces fewer types of chemical agents, has low impurity elements, high recovery efficiency, and low recovery cost, and realizes the green and efficient reuse of ternary battery pole piece powder. At the same time, by using a bag-type anode frame during the electrolysis process, the solid byproducts (such as oxides or precipitates) generated by the ternary positive electrode material of the anode during the electrolysis process can be effectively prevented from directly entering the electrolyte, thereby avoiding the contamination of the post-electrolysis liquid, reducing the difficulty and cost of subsequent treatment, and improving the purity of the recovered product.

[0070] To assist in understanding the above technical solution, the following is a more complete example of a method for recycling ternary positive electrode materials. Figure 2 , provide a ternary positive electrode material for waste batteries, place the ternary positive electrode material in a bag anode frame of an electrolytic cell and perform electrolysis. Due to the use of a bag anode frame, it is possible to effectively prevent anode mud from directly entering the electrolyte and avoid contamination of the post-electrolysis liquid; then collect the post-electrolysis liquid and the alloy powder (i.e., cathode alloy) deposited on the cathode. Adjust the pH of the post-electrolysis liquid to 3.8-4.5, and remove impurities once; adjust the pH of the solution to 9.5-10 again, and remove impurities for a second time; then fill the filtrate of the second impurity removal with carbon dioxide to precipitate lithium to obtain lithium carbonate. For the cathode alloy, a leaching agent can be added for ammonia leaching to obtain a precipitate and a first filtrate; ammonia is evaporated from the first filtrate to obtain a mixed hydroxide of cobalt hydroxide and nickel hydroxide. Acid leaching is performed on the precipitate to obtain a second filtrate; the pH of the second filtrate is adjusted to obtain manganese hydroxide. The mixed hydroxide, lithium salt and manganese hydroxide are mixed and ball-milled to obtain a mixed powder; the mixed powder is roasted to obtain a positive electrode powder.

[0071] In this embodiment, through electrolysis technology, the discharge characteristics of elements are utilized to achieve efficient and clean separation of the target metal elements. This method introduces fewer types of chemical agents, has low impurity elements, high recovery efficiency, and low recovery cost, thereby achieving green and efficient recycling of ternary battery electrode powder.

[0072] In order to enable the details and operations of the above-mentioned embodiments of the present application to be clearly understood by those skilled in the art, as well as to significantly demonstrate the improved performance of the recycling method of the ternary positive electrode material in the embodiments of the present application, the above-mentioned technical scheme is illustrated by means of multiple embodiments below.

[0073] Example 1 (1) Take 1000 g of ternary positive electrode material, the composition of which is shown in Table 1 below; (2) The ternary cathode material is placed in the bag-type anode frame of the electrolytic cell and electrolyzed, wherein the electrolysis voltage is 4.2 V and the current density is 600 mA / cm 2 , the electrolysis temperature is 45 ℃, the electrolysis time is 3 h, the electrolyte includes: sulfuric acid and sodium sulfate, the hydrogen ion concentration of the electrolyte is: 1 mol / L, and the pH is controlled during the electrolysis process; (3) collecting the post-electrolysis liquid, adjusting the pH of the post-electrolysis liquid to 4, and removing impurities once to obtain a primary impurity-removed filtrate; (4) adjusting the pH of the primary impurity-removed filtrate to 10, and performing secondary impurity removal to obtain a secondary impurity-removed filtrate; (5) Carbon dioxide is added to the secondary impurity removal filtrate to precipitate lithium to obtain lithium carbonate, the composition of which is shown in Table 2 below; (6) Use a blade to peel off the deposits on the cathode surface to obtain 457.31 g of alloy powder; (7) mixing the alloy powder with an ammonia leaching agent to obtain a precipitate and a first filtrate, wherein the ammonia leaching agent comprises: aqueous ammonia and ammonium sulfate in a mass ratio of 1:1, wherein the aqueous ammonia concentration is 3 mol / L, the liquid-to-solid ratio is 3, and the leaching time is 2 h; (8) The first filtrate was subjected to ammonia evaporation to obtain 58.06 g of mixed hydroxide, the composition of which is shown in Table 2 below; (9) acid leaching the precipitate to obtain a second filtrate, wherein the acid leaching agent is 15 wt.% sulfuric acid and the liquid-to-solid ratio is 4; (10) The pH of the second filtrate is adjusted to 10 to obtain manganese hydroxide.

[0074] In Example 1, the cobalt leaching rate was 99.73%, the nickel leaching rate was 98.46%, the manganese leaching rate was 5.41%, and the cobalt-nickel direct recovery rate was 96.93%.

[0075] Table 1:

[0076] Table 2:

[0077] Example 2 (1) Take 1000 g of ternary positive electrode material, the composition of which is shown in Table 3 below; (2) The ternary cathode material is placed in the bag-type anode frame of the electrolytic cell and electrolyzed, wherein the electrolysis voltage is 4.2 V and the current density is 800 mA / cm 2 , the electrolysis temperature is 45 ℃, the electrolysis time is 2 h, the electrolyte includes: sulfuric acid and sodium sulfate, the hydrogen ion concentration of the electrolyte is: 1.5 mol / L, and the pH is controlled during the electrolysis process; (3) collecting the post-electrolysis liquid, adjusting the pH of the post-electrolysis liquid to 4, and removing impurities once to obtain a primary impurity-removed filtrate; (4) adjusting the pH of the primary impurity-removed filtrate to 10, and performing secondary impurity removal to obtain a secondary impurity-removed filtrate; (5) Carbon dioxide is added to the secondary impurity removal filtrate to precipitate lithium to obtain lithium carbonate, the composition of which is shown in Table 2 below; (6) Use a blade to peel off the deposits on the cathode surface to obtain 460.31 g of alloy powder; (7) mixing the alloy powder with an ammonia leaching agent to obtain a precipitate and a first filtrate, wherein the ammonia leaching agent comprises: aqueous ammonia and ammonium sulfate in a mass ratio of 1:1, wherein the aqueous ammonia concentration is 2.5 mol / L, the liquid-to-solid ratio is 3, and the leaching time is 1.5 h; (8) The first filtrate was subjected to ammonia evaporation to obtain 55.36 g of mixed hydroxide, the composition of which is shown in Table 4 below; (9) acid leaching the precipitate to obtain a second filtrate, wherein the acid leaching agent is 15 wt.% sulfuric acid and the liquid-to-solid ratio is 4; (10) The pH of the second filtrate is adjusted to 10 to obtain manganese hydroxide, the composition of which is shown in Table 4 below.

[0078] In Example 1, the cobalt leaching rate was 99.15%, the nickel leaching rate was 99.46%, the manganese leaching rate was 3.281%, and the cobalt-nickel direct recovery rate was 95.93%.

[0079] Table 3:

[0080] Table 4:

[0081] Example 3 (1) Take 1000 g of ternary positive electrode material, the composition of which is shown in Table 5 below; (2) The ternary cathode material is placed in the bag-type anode frame of the electrolytic cell and electrolyzed, wherein the electrolysis voltage is 4.8 V and the current density is 800 mA / cm 2 , the electrolysis temperature is 45 ℃, the electrolysis time is 2 h, the electrolyte includes: sulfuric acid and sodium sulfate, the hydrogen ion concentration of the electrolyte is: 1.5 mol / L, and the pH is controlled during the electrolysis process; (3) collecting the post-electrolysis liquid, adjusting the pH of the post-electrolysis liquid to 4, and removing impurities once to obtain a primary impurity-removed filtrate; (4) adjusting the pH of the primary impurity-removed filtrate to 10, and performing secondary impurity removal to obtain a secondary impurity-removed filtrate; (5) Carbon dioxide is added to the secondary impurity removal filtrate to precipitate lithium to obtain lithium carbonate, the composition of which is shown in Table 4 below; (6) Use a blade to peel off the deposits on the cathode surface to obtain 439.77 g of alloy powder; (7) mixing the alloy powder with an ammonia leaching agent to obtain a precipitate and a first filtrate, wherein the ammonia leaching agent comprises: aqueous ammonia and ammonium sulfate in a mass ratio of 1:1, wherein the aqueous ammonia concentration is 3 mol / L, the liquid-to-solid ratio is 3, and the leaching time is 2 h; (8) The first filtrate was subjected to ammonia evaporation to obtain 59.86 g of mixed hydroxide, the composition of which is shown in Table 6 below; (9) acid leaching the precipitate to obtain a second filtrate, wherein the acid leaching agent is 15 wt.% sulfuric acid and the liquid-to-solid ratio is 4; (10) The pH of the second filtrate was adjusted to 10 to obtain manganese hydroxide, the composition of which is shown in Table 6 below.

[0082] In Example 1, the cobalt leaching rate was 98.21%, the nickel leaching rate was 99.27%, the manganese leaching rate was 3.77%, and the cobalt-nickel direct recovery rate was 95.93%.

[0083] Table 5:

[0084] Table 6:

[0085] Comparative Example 1 The experimental steps and raw material ratios are the same as those in Example 1, except that in step (2), the electrolysis voltage is 3 V and the current density is 200 mA / cm 2 .

[0086] In the electrolysis process of Comparative Example 1, no cathode deposits were produced, and gas was produced at both the cathode and the anode, so water was actually electrolyzed. This is because the electrolysis voltage is too low, which is equivalent to electrochemical leaching for the ternary positive electrode material.

[0087] Comparative Example 2 The experimental steps and raw material ratios are the same as those in Example 1, except that the electrolysis voltage in step (2) is 4 V and the current density is 200 mA / cm 2 The electrolyte includes sodium sulfate, the initial hydrogen ion concentration of the electrolyte is 1.5 mol / L, and the pH is not adjusted during the electrolysis process.

[0088] During the electrolysis process of Comparative Example 2, as the electrolysis time increased, the pH of the electrolyte increased; when the pH was greater than 10, a green suspension (hydroxide precipitation) was produced at the cathode, and eventually the plate was burned.

[0089] Comparative Example 3 The experimental steps and raw material ratios are the same as those in Example 1, except that the current density in step (2) is 400 mA / cm 2 , the electrolysis temperature is 85 ℃.

[0090] In Comparative Example 3, the cobalt leaching rate was 59.37%, the nickel leaching rate was 60.18%, the manganese leaching rate was 4.11%, and the cobalt-nickel direct recovery rate was 44.36%. This may be because the electrolysis temperature was too high, and reverse dissolution occurred, which led to a decrease in yield.

[0091] It can be seen from the above experimental results that the embodiments of the present application effectively improve the recovery rate of the ternary positive electrode material and the purity of the recovered product.

Claims

1. A method for recycling ternary positive electrode materials, characterized in that: The method includes: Placing the ternary positive electrode material of the waste battery in a bag-type anode frame of an electrolytic cell and performing electrolysis, wherein the bag-type anode frame comprises a conductive frame and a filter cloth bag wrapping the conductive frame; collecting alloy powder deposited on the cathode of the electrolytic cell; The post-electrolysis liquid is collected, and lithium is precipitated from the post-electrolysis liquid to obtain lithium salt.

2. The method according to claim 1, characterized in that The electrolysis voltage of the electrolytic cell is 3.5-6.5 V, and the current density is 500-800 mA / cm 2 .

3. The method according to claim 1, characterized in that The electrolysis temperature of the electrolytic cell is 40-50°C.

4. The method according to claim 1, characterized in that The hydrogen ion concentration of the electrolyte in the electrolytic cell is: 0.1~2.5 mol / L; And / or, the electrolyte in the electrolytic cell includes: sulfuric acid and / or sodium sulfate.

5. The method according to claim 1, characterized in that After the step of collecting the alloy powder deposited on the cathode of the electrolytic cell, the method further comprises: Performing ammonia leaching on the alloy powder to obtain a precipitate and a first filtrate; Distilling ammonia from the first filtrate to obtain a mixed hydroxide; acid leaching the precipitate to obtain a second filtrate; The pH of the second filtrate is adjusted to obtain manganese hydroxide.

6. The method according to claim 5, characterized in that The leaching agent used in the ammonia leaching includes: ammonium sulfate and ammonia water; The mass ratio of the ammonium sulfate to the ammonia water is (0.5-1):2, and the concentration of the ammonia water is 1-5 mol / L.

7. The method according to claim 5, characterized in that After the step of obtaining the lithium salt, the method further comprises: ball-milling the mixed hydroxide, the lithium salt and the manganese hydroxide to obtain a mixed powder; The mixed powder is calcined to obtain positive electrode powder.

8. The method according to claim 7, characterized in that The calcination temperature is 750-1000°C.

9. The method according to claim 7, characterized in that The step of mixing and ball-milling the mixed hydroxide, the lithium salt and the manganese hydroxide to obtain a mixed powder comprises: A metal source is added to adjust the metal component, wherein the mass ratio of the metals in the mixed powder is Li:Ni:Co:Mn=(1~1.02):(0.5~0.65):(0.2~0.25):(0.2~0.35).

10. The method according to claim 1, characterized in that The step of precipitating lithium in the electrolyte comprises: Adjusting the pH of the electrolyzed solution to 3.8-4.5 and removing impurities at one time; The pH of the post-electrolysis solution is adjusted to 9.5-10, and impurities are removed for a second time.

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