Separation method of inorganic powder in lithium battery anode and cathode materials

Abstract

The invention discloses a separation method of inorganic powder in lithium battery positive and negative electrode materials, and relates to the technical field of lithium batteries. Comprising the following steps: taking a mixture of materials in the waste lithium battery, and pretreating the mixture to obtain pretreated powder; performing dry powder mixing on the pretreated powder and a surfactant to obtain powder after dry powder mixing, preparing slurry, and grinding the slurry to obtain dispersed slurry; and adding a cationic flocculant into the dispersed slurry, and after the dispersed slurry is precipitated and layered, separating the precipitated dispersed slurry to obtain a lower-layer precipitate and drying the lower-layer precipitate to obtain the inorganic powder. According to the method, a physical separation means is adopted, the carbon powder in the mixture of the positive electrode material and the negative electrode material in the waste lithium battery is accurately and efficiently separated, the inorganic powder after the carbon powder is separated is obtained, and reutilization of the inorganic powder is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a method for separating inorganic powders in positive and negative electrode materials of lithium batteries. Background Art

[0002] In some related technologies, the material after crushing of waste lithium batteries is a mixture of positive and negative electrode materials, in which the carbon content is very high, usually greater than 30%. The usual practice is to directly enter the mixture into the hydrometallurgical process, dissolve the mixture powder into an acid solution or an alkaline solution, and treat the carbon powder as hydrometallurgical slag. In the actual processing process, the carbon powder enters the metallurgical process as an ineffective material, and when discharging, it will absorb and carry a large amount of effective material solution, which requires a large amount of water to wash, which not only reduces production efficiency but also increases environmental costs.

[0003] Through other methods, such as through an oxidizing roasting atmosphere, using carbon and oxygen, carbon and carbon monoxide, carbon and water vapor to react, although some carbon powder can be separated, the carbon content in the black powder is greatly reduced; or, carbon separation is achieved through flotation, and the flotation process has a low separation efficiency for carbon powder. Summary of the invention

[0004] In order to solve at least one of the problems mentioned in the above background technology, the present application provides a method for separating inorganic powders in lithium battery materials, which uses physical separation means to accurately separate the carbon powder in the mixture of positive and negative electrode materials contained in waste lithium batteries to obtain inorganic powder after separating the carbon powder, so as to achieve the reuse of the inorganic powder.

[0005] The specific technical solutions provided by the embodiments of this application are as follows:

[0006] In a first aspect, a method for separating inorganic powders in positive and negative electrode materials of a lithium battery is provided, the method comprising:

[0007] Obtaining a mixture of materials from waste lithium batteries, and pre-treating the mixture to obtain a pre-treated powder;

[0008] The pretreated powder is mixed with a surfactant by dry powder, and the dry powder is obtained to prepare a slurry, and the slurry is ground to obtain a dispersed slurry;

[0009] A cationic flocculant is added to the dispersed slurry, and after the dispersed slurry is precipitated and layered, the dispersed slurry after precipitation is separated, and the lower layer of precipitated material is obtained and dried to obtain an inorganic powder.

[0010] In a specific embodiment, the upper layer of the dispersion liquid after the dispersion slurry is precipitated and separated is obtained, and the upper layer of the dispersion liquid is filtered and dried to obtain the carbonaceous powder.

[0011] In a specific embodiment, the mass ratio of the added amount of the surfactant to the pretreated powder is 0.001:1 to 0.03:1;

[0012] Furthermore, the mass ratio of the added amount of the surfactant to the pretreated powder is 0.005:1 to 0.02:1.

[0013] The surfactant is selected as an anionic dispersant; further, the surfactant includes one or more of sodium dodecylbenzene sulfonate, ammonium dodecyl sulfate, sodium polyacrylate, polyacrylic acid amine and fatty alcohol polyoxyethylene ether;

[0014] The surfactant and the pretreated powder are mixed by stirring, and the stirring treatment time is 0.5 to 3 hours;

[0015] Furthermore, the stirring treatment time is 1 to 2 hours.

[0016] In a specific embodiment, the step of obtaining a powder after dry powder mixing and preparing a slurry, and grinding the slurry to obtain a dispersed slurry specifically includes: adding a dispersant to a dispersion medium and mixing evenly to obtain a dispersion solvent; adding the powder after dry powder mixing to the dispersion solvent, and grinding and dispersing the mixture; after grinding and dispersing for a first preset time, taking the dispersed slurry within a continuous time period, and detecting the D90 particle size of the dispersed slurry; if the D90 particle size changes by less than 15% within the continuous time period, the dispersion is confirmed to be complete;

[0017] Furthermore, when the D90 particle size changes by less than 10% within the continuous time period, the dispersion is confirmed to be complete; then a stabilizer is added, and the dispersion is continued for a second preset time to obtain a dispersed slurry.

[0018] In a specific embodiment, the mass ratio of the powder after the dispersant is mixed with the dry powder is 0.001:1 to 0.2:1; further, the mass ratio of the powder after the dispersant is mixed with the dry powder is 0.001:1 to 0.1:1;

[0019] The mass ratio of the powder after the dispersion medium and the dry powder are mixed is 100:1 to 100:35; further, the mass ratio of the powder after the dispersion medium and the dry powder are mixed is 100:1 to 100:30;

[0020] The mass ratio of the stabilizer to the dry powder after mixing is 0.001:1 to 0.1:1; further, the mass ratio of the stabilizer to the dry powder after mixing is 0.001:1 to 0.03:1.

[0021] In a specific embodiment, the dispersant is selected as a non-ionic dispersant; further, the dispersant includes one or more of propylene glycol monostearate, polyoxyethylene ether, sorbitan monooleate, sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyvinyl pyrrolidone, acrylic ionic dispersant, benzyltrimethylammonium chloride, sodium dodecyl sulfate, and sodium methylene bisnaphthalene sulfonate.

[0022] In a specific embodiment, the dispersion medium includes one or more of water, ethanol, propanol, ethylene glycol, nitrogen-methyl pyrrolidone, and nitrogen-nitrogen dimethylformamide.

[0023] In a specific embodiment, the stabilizer includes one or more of nonionic polyacrylamide, polyethylene glycol, and polyvinyl acetate.

[0024] In a specific embodiment, the cationic flocculant includes cationic polyacrylamide, poly(diallyl methylammonium chloride) or a mixture of the cationic polyacrylamide and the poly(diallyl methylammonium chloride) in a preset ratio.

[0025] In a specific embodiment, pretreating the mixture includes calcining or cleaning the mixture; wherein the calcination temperature is 400-800°C; further, the calcination temperature is 400-600°C; the calcination treatment time is 0.5-4h; further, the calcination treatment time is 0.5-2h; or the mixture is cleaned with a cleaning agent; wherein the cleaning agent includes one or more of nitrogen-methyl pyrrolidone, nitrogen-nitrogen dimethylformamide or dimethyl carbonate.

[0026] In a second aspect, a positive electrode material is provided, wherein the positive electrode material comprises an inorganic powder, and the inorganic powder is separated by the above-mentioned method for separating inorganic powders in positive and negative electrode materials of a lithium battery.

[0027] In a third aspect, a lithium battery is provided, comprising the positive electrode material, the negative electrode material and the electrolyte as described above.

[0028] The embodiments of the present application have the following beneficial effects:

[0029] 1. The separation method provided in the embodiment of the present application obtains pretreated powder by calcining and washing the mixture in the waste lithium battery, and then dry-mixes the pretreated powder with a surfactant to obtain the powder after dry powder mixing and makes it into slurry, grinds the slurry to obtain dispersed slurry, adds a cationic flocculant to the dispersed slurry, and after the dispersed slurry is precipitated and stratified, obtains the lower layer of precipitated material and dries it to obtain inorganic powder, and adopts physical dispersion separation means to accurately separate the carbon powder in the mixture containing positive and negative electrode materials in the waste lithium battery to obtain inorganic powder after the carbon powder is separated, so as to realize the reuse of the inorganic powder.

[0030] 2. The mixture of waste lithium batteries in this scheme mainly includes metal powder particles, graphite and conductive agent, wherein the metal powder particles mainly include lithium iron phosphate, ternary lithium, etc. In the initial mixture, due to the large surface energy of several particles, the particles are adsorbed together and difficult to separate. According to the scheme in this embodiment, the added surfactant is anionic, and the anionic surfactant is strongly combined with the surface of the metal particles to achieve the effect of occupying and infiltrating. Further, a non-ionic dispersant is used, and it has a conjugated structure, so that the dispersant is mainly adsorbed on the surface of graphite or carbon black, ensuring that the graphite and carbon black in the mixture are effectively dispersed; in the later stage of dispersion, a cationic flocculant is added to the dispersion system. Since the anionic dispersant is adsorbed on the surface of the metal particles, the cationic flocculant added can capture the metal powder particles in a direction, thereby enhancing the separation effect between the metal particles and the graphite and carbon black, that is, the carbon content in the carbon-containing powder is above 90%, so that the purity of the inorganic powder obtained after dispersion is higher.

[0031] 3. Furthermore, by adding a stabilizer during the dispersion and pulping process, the stabilizer has a viscosity-increasing and wetting effect, and the molecular weight of the stabilizer is usually large, which can further enhance the dispersion stability of graphite and carbon black in the dispersion slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic diagram showing a method for separating inorganic powders from positive and negative electrode materials of a lithium battery according to the present application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] The first step in recycling waste lithium batteries is to obtain a mixture of positive and negative electrodes from waste lithium batteries. Positive electrode powder is divided into lithium iron phosphate, ternary, lithium manganese oxide, lithium cobalt oxide, etc. according to different raw materials. The negative electrode is usually graphite, silicon carbon and other similar carbon material powder. After the two materials are mixed, they cannot be directly separated due to their fine particle size. This causes the black powder to always carry a large amount of invalid carbon powder when it is recycled, and these carbon powders must be removed in the subsequent process.

[0037] Embodiment 1

[0038] Based on the above problems, Figure 1 As shown, this embodiment provides a method for separating inorganic powders in positive and negative electrode materials of a lithium battery, which specifically includes the following steps:

[0039] Step 1: Obtain a mixture of materials from waste lithium batteries, and pretreat the mixture to obtain a pretreated powder.

[0040] It should be noted that the mixture in the directly obtained waste lithium batteries includes the positive and negative electrode materials of the batteries. The binder, residual electrolyte and other impurities in the mixture can be removed through pretreatment processes such as roasting or cleaning, wherein the roasting temperature is 400-600°C; the roasting treatment time is 0.5-2h; or the mixture is cleaned with a cleaning agent; wherein the cleaning agent includes but is not limited to one or more of nitrogen-methyl pyrrolidone, nitrogen-nitrogen dimethylformamide or dimethyl carbonate.

[0041] The mixture can be degummed by washing it with the above-mentioned cleaning agent; alternatively, the mixture can be washed with water or ethanol solution instead of the cleaning agent; alternatively, the mixture can be continued to the next process without washing.

[0042] Step 2: dry-mix the pretreated powder with a surfactant, obtain the dry-mixed powder and make it into slurry, grind the slurry to obtain a dispersed slurry.

[0043] Specifically, the mass ratio of the added amount of the surfactant to the pretreated powder is 0.005:1 to 0.02:1; the surfactant is selected as an anionic dispersant; further, the surfactant includes but is not limited to one or more of sodium dodecylbenzene sulfonate, ammonium dodecyl sulfate, sodium polyacrylate, polyacrylic acid amine and fatty alcohol polyoxyethylene ether; the surfactant and the pretreated powder are mixed by stirring, and the stirring treatment time is 1 to 2 hours.

[0044] The step of obtaining a powder after dry powder mixing and making it into a slurry, and grinding the slurry to obtain a dispersed slurry specifically includes: adding a dispersant to a dispersion medium and mixing evenly to obtain a dispersed solvent; adding the powder after dry powder mixing to the dispersed solvent and grinding and dispersing the mixture; after grinding and dispersing for a first preset time, taking the dispersed slurry within a continuous time period, and detecting the D90 particle size of the dispersed slurry; when the D90 particle size changes by less than 10% within the continuous time period, the dispersion is confirmed to be complete; and then adding a stabilizer and continuing to disperse for a second preset time to obtain a dispersed slurry.

[0045] Furthermore, in the process of preparing the dispersed slurry, relevant equipment is used for grinding, specifically including sand mill grinding, ball mill grinding, homogenizer grinding or ultrasonic grinding dispersion.

[0046] Exemplarily, after adding the dry powder mixture to the dispersing solvent, a sand mill is used for grinding and dispersion. When the particle size of the dispersion D90 is sampled for 5 consecutive minutes and the change is less than 10%, the dispersion is judged to be complete, and then a stabilizer is added, and the dispersion is continued for 5 minutes, and then the dispersion is stopped and the next step is entered.

[0047] Among them, the mass ratio of the powder after the dispersant and the dry powder are mixed is 0.001:1 to 0.1:1; the dispersant includes but is not limited to one or more of propylene glycol monostearate, polyoxyethylene ether, sorbitan monooleate, sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyvinyl pyrrolidone, acrylic ionic dispersant, benzyltrimethylammonium chloride, sodium dodecyl sulfate, and sodium methylene bisnaphthalene sulfonate.

[0048] Among them, the mass ratio of the powder after the dispersion medium and the dry powder are mixed is 100:1 to 100:30; the dispersion medium includes but is not limited to one or more of water, ethanol, propanol, ethylene glycol, nitrogen-methyl pyrrolidone, and nitrogen-nitrogen dimethylformamide.

[0049] Among them, the mass ratio of the stabilizer to the dry powder after mixing is 0.001:1 to 0.03:1; the stabilizer includes but is not limited to one or more of non-ionic polyacrylamide, polyethylene glycol, and polyvinyl acetate.

[0050] Step 3: adding a cationic flocculant to the dispersed slurry, and after the dispersed slurry is precipitated and layered, separating the dispersed slurry after precipitation, obtaining the lower layer of precipitated material and drying it to obtain an inorganic powder.

[0051] Furthermore, the upper dispersion liquid in the dispersed slurry after precipitation and stratification is obtained, filtered and dried to obtain a carbon-containing powder, wherein the carbon content in the carbon-containing powder is greater than 95%. By detecting the carbon content in the upper dispersion liquid, it is determined that most of the carbon powder in the mixture is dispersed in the dispersion liquid, thereby ensuring that the purity of the precipitated inorganic powder obtained in the lower layer is higher.

[0052] By adding cationic flocculants in the later stage of dispersion, the separation effect of powder particles and carbon particles can be further enhanced.

[0053] In this embodiment, a centrifugal device can be configured to separate the dispersed slurry after precipitation. The specific centrifugal device includes but is not limited to a horizontal spiral centrifuge, a tubular centrifuge, a disc centrifuge or one of the centrifugal separations, wherein the centrifugal force during the centrifugal treatment process is set to 1500-3000g.

[0054] Through the scheme in this embodiment, physical separation means are used to accurately separate the carbon powder in the mixture of positive and negative electrode materials in waste lithium batteries, and obtain inorganic powder after separating the carbon powder, so as to achieve the reuse of the inorganic powder without affecting the properties of the separated inorganic powder itself.

[0055] Embodiment 2

[0056] Step 101, obtaining a mixture of black powder of waste lithium battery materials. Specifically, in this embodiment, 5 kg of a mixture of black powder produced by a ternary lithium battery is selected, and the mixture is roasted at a temperature of 550° C. for 1.5 hours to obtain a pre-treated powder;

[0057] Step 102, selecting sodium dodecylbenzene sulfonate as a surfactant, the addition amount of sodium dodecylbenzene sulfonate is 0.1% of the mass of the mixture, stirring and mixing the pretreated powder and the sodium dodecylbenzene sulfonate for 0.5 h to obtain a dry powder mixed powder;

[0058] Step 103, selecting polyvinyl pyrrolidone as the dispersant and ethanol as the dispersing solvent, the amount of polyvinyl pyrrolidone used in the prepared dispersing solvent is 0.5% of the mass of the powder after the dry powder is mixed, and the powder after the dry powder is mixed and the dispersing solvent are ground and dispersed in a ratio of 1:3, and selecting polyethylene glycol as the stabilizer, the amount of polyethylene glycol used is 0.8% of the powder after the dry powder is mixed, and a dispersed slurry is obtained after the dispersion is completed;

[0059] Step 104, selecting polymethyldiallyl ammonium chloride as the cationic flocculant, and obtaining inorganic powder after precipitation and stratification, wherein the yield of the inorganic powder is 75%, and the carbon content of the inorganic powder is 4.8%.

[0060] Embodiment 3

[0061] Corresponding to the above embodiment, the difference between this embodiment and the second embodiment is that the amount of the surfactant sodium dodecylbenzene sulfonate used is different. In this embodiment, the amount of the surfactant sodium dodecylbenzene sulfonate used is 1.5% of the mass of the mixture.

[0062] Embodiment 4

[0063] Corresponding to the above-mentioned embodiment, the difference between this embodiment and the second embodiment is that the amount of the dispersant polyvinyl pyrrolidone is different. The amount of the dispersant polyvinyl pyrrolidone in this embodiment is 3.5% of the mass of the powder after the dry powder is mixed.

[0064] Embodiment 5

[0065] Corresponding to the above-mentioned embodiment, the difference between this embodiment and the second embodiment is that the amount of the surfactant sodium dodecylbenzene sulfonate used is different. The amount of the surfactant sodium dodecylbenzene sulfonate used in this embodiment is 3% of the mass of the mixture.

[0066] Embodiment 6

[0067] Corresponding to the above embodiment, the difference between this embodiment and embodiment 3 is that the dispersant is a mixture of polyvinyl pyrrolidone and sorbitan monostearate, wherein the amount of the dispersant polyvinyl pyrrolidone in this embodiment is 0.3% of the mass of the powder after the dry powder is mixed, and the amount of sorbitan monostearate is 0.2% of the mass of the powder after the dry powder is mixed.

[0068] Embodiment 7

[0069] Step 101, in this embodiment, 5 kg of mixed black powder produced by lithium iron phosphate battery is selected, and the mixture is roasted at a temperature of 600° C. for 2 hours to obtain a pretreated powder, and the carbon content of the pretreated powder is 25%;

[0070] Step 102, selecting a surfactant as fatty alcohol polyoxyethylene ether, the amount of fatty alcohol polyoxyethylene ether added is 0.1% of the mass of the mixture, stirring and mixing the pretreated powder and the fatty alcohol polyoxyethylene ether for 0.5 h to obtain a dry powder mixed powder;

[0071] Step 103, selecting polyoxyethylene sorbitan monooleate as a dispersant, water as a dispersing solvent, the amount of polyoxyethylene sorbitan monooleate used in the prepared dispersing solvent is 2% of the mass of the powder after the dry powder is mixed, and the powder after the dry powder is mixed and the dispersing solvent are ground and dispersed in a ratio of 1:4, and polyethylene glycol is selected as a stabilizer, and the amount of polyethylene glycol used is 1% of the powder after the dry powder is mixed, and a dispersed slurry is obtained after the dispersion is completed;

[0072] Step 104, selecting cationic polyacrylamide as the cationic flocculant, and obtaining inorganic powder after precipitation and stratification, wherein the yield of the inorganic powder is 94%, and the carbon content of the inorganic powder is 2.3%.

[0073] It can be seen from the scheme in this embodiment that for lithium iron phosphate positive and negative electrode powders, the treatment method in this scheme can also achieve carbon powder separation by selecting suitable surfactants, dispersants and dispersion systems, and achieve precise separation of carbon powder in the mixture. The carbon content in the inorganic powder after separating the carbon powder is only 2.3%, which can achieve the reuse of the inorganic powder.

[0074] Embodiment 8

[0075] Step 101, in this embodiment, 5 kg of black powder of the positive electrode material peeled from the scrapped lithium iron phosphate electrode is selected, and the black powder of the positive electrode material of the lithium iron phosphate battery is roasted at a roasting temperature of 550° C. for 1.5 hours to obtain a pretreated powder, and the carbon content of the pretreated powder is 4.5%;

[0076] Step 102, selecting a surfactant as fatty alcohol polyoxyethylene ether, the amount of fatty alcohol polyoxyethylene ether added is 2.5% of the mass of the mixture, stirring and mixing the pretreated powder and the fatty alcohol polyoxyethylene ether for 0.5 h to obtain a dry powder mixed powder;

[0077] Step 103, selecting a dispersant as a mixture of polyoxyethylene sorbitan monooleate and polyvinyl pyrrolidone, and a dispersing solvent as ethanol. The prepared dispersing solvent, the amount of polyoxyethylene sorbitan monooleate is 0.2% of the mass of the powder after the dry powder is mixed, the amount of polyvinyl pyrrolidone is 0.8% of the mass of the powder after the dry powder is mixed, and the powder after the dry powder is mixed and the dispersing solvent are ground and dispersed in a ratio of 1:4, and the stabilizer is selected as polyvinyl acetate, and the amount of polyvinyl acetate is 1% of the powder after the dry powder is mixed, and a dispersed slurry is obtained after the dispersion is completed;

[0078] Step 104, cationic polyacrylamide is selected as the cationic flocculant, and inorganic powder is obtained after precipitation and stratification, wherein the yield of the inorganic powder is 96%, and the carbon content of the inorganic powder is 1.2%.

[0079] When the black powder to be processed is lithium iron phosphate powder, the scheme in this embodiment can also effectively separate carbon from lithium iron phosphate powder with a low carbon content, and the carbon content in the obtained inorganic powder is only 1.2%.

[0080] Embodiment 9

[0081] Corresponding to the above embodiment, a positive electrode material is provided, wherein the positive electrode material comprises an inorganic powder, and the inorganic powder is separated by the above-mentioned method for separating inorganic powder from positive and negative electrode materials of a lithium battery.

[0082] Among them, the method for separating inorganic powders from positive and negative electrode materials of lithium batteries includes obtaining a mixture of materials from waste lithium batteries, pre-treating the mixture to obtain pre-treated powder; dry-mixing the pre-treated powder with a surfactant to obtain a powder after dry powder mixing and making it into a slurry, grinding the slurry to obtain a dispersed slurry; adding a cationic flocculant to the dispersed slurry, and after the dispersed slurry is precipitated and layered, separating the precipitated dispersed slurry, obtaining the lower layer of precipitated material and drying it to obtain an inorganic powder.

[0083] The specific limitations on the separation method of inorganic powders in the positive and negative electrode materials of the lithium battery can be found in the limitations on the separation method of inorganic powders in the positive and negative electrode materials of the lithium battery in Example 1, which will not be repeated here.

[0084] Embodiment 10

[0085] Corresponding to the above embodiment, a lithium battery is provided, comprising the positive electrode material, negative electrode material and electrolyte as described above, wherein the positive electrode material comprises inorganic powder, and the inorganic powder is separated by the above-mentioned method for separating inorganic powder from positive and negative electrode materials of a lithium battery.

[0086] Among them, the method for separating inorganic powders from positive and negative electrode materials of lithium batteries includes obtaining a mixture of materials from waste lithium batteries, pre-treating the mixture to obtain pre-treated powder; dry-mixing the pre-treated powder with a surfactant to obtain a powder after dry powder mixing and making it into a slurry, grinding the slurry to obtain a dispersed slurry; adding a cationic flocculant to the dispersed slurry, and after the dispersed slurry is precipitated and layered, separating the precipitated dispersed slurry, obtaining the lower layer of precipitated material and drying it to obtain an inorganic powder.

[0087] The specific limitations on the separation method of inorganic powders in the positive and negative electrode materials of the lithium battery can be found in the limitations on the separation method of inorganic powders in the positive and negative electrode materials of the lithium battery in Example 1, which will not be repeated here.

[0088] Comparative Example 1

[0089] Corresponding to the above-mentioned embodiment, the difference between this embodiment and the fourth embodiment is that the amount of the surfactant sodium dodecylbenzene sulfonate used is different. The amount of the surfactant sodium dodecylbenzene sulfonate used in this embodiment is 0.

[0090] Comparative Example 2

[0091] Corresponding to the above-mentioned embodiment, the difference between this embodiment and the second embodiment is that the amount of the surfactant sodium dodecylbenzene sulfonate used is different. The amount of the surfactant sodium dodecylbenzene sulfonate used in this embodiment is 5% of the mass of the mixture.

[0092] Comparative Example 3

[0093] Corresponding to the above-mentioned embodiment, the difference between this embodiment and the fifth embodiment is that the amount of the dispersant polyvinyl pyrrolidone used is different. The amount of the dispersant polyvinyl pyrrolidone used in this embodiment is 0.

[0094] Comparative Example 4

[0095] Corresponding to the above embodiment, the difference between this embodiment and embodiment 3 is that the amount of the stabilizer polyethylene glycol used is different. The amount of the stabilizer polyethylene glycol used in this embodiment is 0.

[0096] A comprehensive analysis of different separation conditions in Examples 2 to 6 and Comparative Examples 1 to 4 was performed to compare and analyze the results shown in Table 1.

[0097] Table 1 Test results of inorganic powders in Examples and Comparative Examples

[0098]

[0099] Through the dosage of each additive in each group of Example 2 and Example 3 and the test results of the obtained inorganic powder, it can be seen that within the addition range of the surfactant in this embodiment, as the dosage of the surfactant increases, the yield of the prepared inorganic powder also increases, and the carbon content in the inorganic powder is maintained at a low level; compared with Example 2 and Example 4, it can be seen that the dosage of the dispersant is increased, but the dosage of the surfactant is controlled at a general level. Since the increase in the dosage of the dispersant can play an auxiliary role in the subsequent dispersion of the powder, therefore, increasing the dosage of the dispersant can also achieve efficient carbon separation, and the yield is slightly improved, but it is still not as good as the separation effect obtained by configuring the surfactant and the dispersant in a suitable proportion.

[0100] Through the combined analysis of the various parameters and separation results in Example 2 and Example 5, it can be seen that while keeping the amount of dispersant unchanged, increasing the amount of surfactant can also obtain a better separation effect, but the carbon content in the final inorganic powder will increase slightly; selecting a mixture of two or more dispersants as a dispersant will improve the separation effect of this scheme, so that the yield of the final inorganic powder is increased and the carbon content is reduced.

[0101] Furthermore, from the comparison example 1 and the example 4, it can be seen that the carbon powder separation can be achieved by increasing the amount of dispersant without adding a surfactant, but because the dispersant also has the effect of dispersing inorganic powder particles, the final inorganic powder yield is low; from the comparison example 2 and the example 2, it can be seen that when the amount of surfactant is increased, the excess surfactant will also participate in the dispersion of the carbon powder, resulting in excessive anionic substances on the surface of the carbon powder, and a large amount of carbon powder will settle with the inorganic powder during the flocculation separation process, resulting in a product with too high carbon content; from the comparison example 3 and the example 5, it can be seen that when the surfactant is used normally but the dispersant is not used, the carbon powder cannot be effectively dispersed. In the actual separation process, the carbon powder is always adsorbed on the surface of the inorganic powder and settles with the inorganic powder. Therefore, the carbon content in the obtained inorganic powder is relatively high; from the comparison example 4 and the example 3, it can be seen that without adding a stabilizer, the stability of the system is slightly poor, which has little effect on the yield, but will increase the carbon content of the organic powder.

[0102] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present application.

[0103] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for separating inorganic powders from positive and negative electrode materials of lithium batteries, characterized in that: The method comprises: Obtaining a mixture of waste lithium battery materials, and pretreating the mixture to obtain a pretreated powder; The pretreated powder is mixed with a surfactant by dry powder, and the dry powder is obtained to prepare a slurry, and the slurry is ground to obtain a dispersed slurry; A cationic flocculant is added to the dispersed slurry, and after the dispersed slurry is precipitated and layered, the dispersed slurry after precipitation is separated, and the lower layer of precipitated material is obtained and dried to obtain an inorganic powder.

2. The method for separating inorganic powders in positive and negative electrode materials of lithium batteries according to claim 1, characterized in that: The method further comprises: The upper layer of the dispersion liquid after the dispersion slurry is precipitated and layered is obtained, and the upper layer of the dispersion liquid is filtered and dried to obtain the carbonaceous powder.

3. The method for separating inorganic powder from positive and negative electrode materials of lithium batteries according to claim 1 or 2, characterized in that: The method further comprises: The mass ratio of the added amount of the surfactant to the pretreated powder is 0.001:1 to 0.03:1; Preferably, the mass ratio of the added amount of the surfactant to the pretreated powder is 0.005:1 to 0.02:1; The surfactant is selected as an anionic dispersant; Preferably, the surfactant includes one or more of sodium dodecylbenzene sulfonate, ammonium dodecyl sulfate, sodium polyacrylate, polyacrylic acid amine and fatty alcohol polyoxyethylene ether; The surfactant and the pretreated powder are mixed by stirring, and the stirring treatment time is 0.5 to 3 hours; Preferably, the stirring treatment time is 1 to 2 hours.

4. The method for separating inorganic powders from positive and negative electrode materials of lithium batteries according to claim 3, characterized in that: The step of obtaining a powder after mixing the dry powder and preparing a slurry, and grinding the slurry to obtain a dispersed slurry specifically comprises: Adding the dispersant to the dispersion medium and mixing evenly to obtain a dispersion solvent; Adding the dry powder mixture into the dispersion solvent, and grinding and dispersing the mixture; After the first preset grinding and dispersing time, the dispersed slurry is taken within a continuous time period to detect the D90 particle size of the dispersed slurry; If the D90 particle size changes by less than 15% over a continuous period of time, dispersion is confirmed to be complete; Wherein, when the D90 particle size changes by less than 10% within the continuous time period, the dispersion is confirmed to be complete; Then, a stabilizer is added, and dispersion is continued for a second preset time to obtain a dispersed slurry.

5. The method for separating inorganic powder from positive and negative electrode materials of lithium batteries according to claim 4, characterized in that: The mass ratio of the powder after the dispersant and the dry powder are mixed is 0.001:1 to 0.2:1; Preferably, the mass ratio of the powder after the dispersant is mixed with the dry powder is 0.001:1 to 0.1:1; The mass ratio of the powder after the dispersion medium and the dry powder are mixed is 100:1 to 100:35; Preferably, the mass ratio of the powder after the dispersion medium and the dry powder are mixed is 100:1 to 100:30; The mass ratio of the stabilizer to the dry powder after mixing is 0.001:1 to 0.1:1; Preferably, the mass ratio of the stabilizer to the dry powder after mixing is 0.001:1 to 0.03:

1.

6. The method for separating inorganic powders from positive and negative electrode materials of lithium batteries according to claim 4, characterized in that: The dispersant is selected as a non-ionic dispersant; Preferably, the dispersant includes one or more of propylene glycol monostearate, polyoxyethylene ether, sorbitan monooleate, sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyvinyl pyrrolidone, acrylic acid ionic dispersant, benzyltrimethylammonium chloride, sodium dodecyl sulfate, and sodium methylene bisnaphthalene sulfonate; The dispersion medium includes one or more of water, ethanol, propanol, ethylene glycol, nitrogen-methyl pyrrolidone, and nitrogen-nitrogen dimethylformamide; The stabilizer includes one or more of nonionic polyacrylamide, polyethylene glycol, and polyvinyl acetate.

7. The method for separating inorganic powders from positive and negative electrode materials of lithium batteries according to claim 6, characterized in that: The method further comprises: The cationic flocculant includes cationic polyacrylamide, poly(diallyl methyl ammonium chloride) or a mixture of the cationic polyacrylamide and the poly(diallyl methyl ammonium chloride) in a preset ratio.

8. The method for separating inorganic powders from positive and negative electrode materials of lithium batteries according to claim 1 or 2, characterized in that: Pre-treating the mixture includes roasting or washing the mixture; The calcination temperature is 400-800°C; Preferably, the calcination temperature is 400-600°C; The calcination treatment time is 0.5 to 4 hours; Preferably, the calcination treatment time is 0.5 to 2 hours; or cleaning the mixture with a cleaning agent; Wherein, the cleaning agent includes one or more of nitrogen-methyl pyrrolidone, nitrogen-nitrogen dimethylformamide or dimethyl carbonate.

9. A positive electrode material, characterized in that: The positive electrode material comprises inorganic powder, and the inorganic powder is separated by the method for separating inorganic powder from positive and negative electrode materials for lithium batteries according to any one of claims 1 to 8.

10. A lithium battery, characterized in that: It comprises the positive electrode material, negative electrode material and electrolyte as claimed in claim 9.

Images