Application of carbon material recovered from waste battery negative electrode in electrochemical wastewater treatment

Abstract

The application provides application of a carbon material recovered from a negative electrode of a waste battery in electrochemical wastewater treatment and belongs to the technical field of waste battery recovery. In the application, the carbon material is prepared into an electrochemical cathode and used for electrochemical wastewater treatment. The application can realize resource utilization of graphite in the waste battery, and the corresponding electrochemical cathode also has the advantage of high wastewater treatment effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste battery recycling, in particular to application of carbon material recovered from waste battery negative electrode in electrochemical wastewater treatment. BACKGROUND

[0002] In the prior art, for the scrapped batteries (such as lithium ion batteries), the recovery of valuable metals and current collectors (such as lithium, nickel, cobalt, manganese, copper and aluminum) in the positive electrode has attracted widespread attention due to its huge economic benefits. However, the negative electrode material (graphite) is usually discarded directly due to its lower economic benefits, thereby causing great environmental pressure. If these graphites can be recycled and utilized, the environmental burden can be greatly reduced. At present, for these recovered graphites, they are mainly prepared into battery negative electrodes for application, but the prepared batteries have the problem of rapid performance degradation, which makes it difficult to effectively utilize the graphites recovered from the negative electrodes of waste batteries. SUMMARY

[0003] The present application aims to provide application of carbon material recovered from waste battery negative electrode in electrochemical wastewater treatment, so as to realize the resource utilization of graphite in waste batteries, and the corresponding electrochemical cathode has the advantage of higher wastewater treatment effect.

[0004] The embodiments of the present application are implemented as follows:

[0005] The embodiments of the present application provide application of carbon material recovered from waste battery negative electrode in electrochemical wastewater treatment, the carbon material is prepared into an electrochemical cathode and used for electrochemical wastewater treatment.

[0006] In the above technical solution, the carbon material recovered from the negative electrode of waste batteries is prepared into an electrochemical cathode and used for wastewater treatment, which can provide a more reasonable new way for the resource utilization of graphite. In addition, compared with the preparation of commercially available graphite into an electrochemical cathode, the preparation of the carbon material recovered from the negative electrode of waste batteries into an electrochemical cathode has the advantage of higher water treatment efficiency.

[0007] In some optional embodiments, the process of recovering the carbon material from the negative electrode of waste batteries and preparing the carbon material into an electrochemical cathode and using the electrochemical cathode for electrochemical wastewater treatment includes the following steps:

[0008] A carbon material precursor obtained from the negative electrode of waste batteries is provided; the carbon material precursor is subjected to crushing, acid soaking, solid-liquid separation and cleaning in sequence to obtain a carbon material; the carbon material and a binder are mixed, and the mixed slurry is coated on the surface of a conductive metal to obtain an electrochemical cathode intermediate; the electrochemical cathode intermediate is subjected to flattening and drying in sequence to obtain an electrochemical cathode; and the electrochemical cathode is applied to electrochemical wastewater treatment.

[0009] According to the specific preparation process provided in the embodiments of the present application, the carbon material recovered from the negative electrode of the waste battery can be prepared into an electrochemical cathode with high water treatment efficiency. In the process, the carbon material precursor is crushed to obtain carbon material particles with small particle size, so as to pursue higher specific surface area, so that the corresponding electrochemical cathode has higher water treatment efficiency, and the heavy metal ions in the carbon material can also be effectively removed. The acid soaking is to effectively separate the carbon material and the heavy metal ions (the presence of heavy metals is easy to cause secondary pollution), so as to reduce the risk of secondary pollution in the subsequent application process. The mixed slurry is coated on the surface of the conductive metal and used to prepare the electrochemical cathode, which can reduce the amount of carbon material used, thereby saving costs. In addition, the electrochemical cathode is prepared by coating and curing, which has the advantages of simple and efficient preparation process.

[0010] In some optional embodiments, the particle size D50 of the carbon material precursor is 100-200 nm during the crushing process.

[0011] In the above technical solution, the particle size of the carbon material precursor is controlled within a certain range, so that the particles have an ideal specific surface area, thereby making the electrochemical cathode have higher water treatment efficiency, and the heavy metal ions in the carbon material can also be more effectively removed.

[0012] In some optional embodiments, the acid soaking process includes the following steps: transferring the crushed carbon material precursor into the acid solution and stirring under heating conditions.

[0013] In the above technical solution, the acid soaking process is carried out under heating conditions, which can make the heavy metal ions and the carbon material more easily and efficiently separated, so as to more thoroughly remove the heavy metal ions in the carbon material, thereby further reducing the risk of secondary pollution in the subsequent application process.

[0014] In some optional embodiments, the acid solution also includes a chloride salt.

[0015] In the above technical solution, the chloride salt is added to the acid solution, and by virtue of the corrosive nature of chloride ions, the heavy metal ions in the carbon material can be more thoroughly removed, thereby further reducing the risk of secondary pollution in the subsequent application process.

[0016] In some optional embodiments, the chloride salt includes potassium chloride and / or sodium chloride.

[0017] In the above technical solution, a specific type of chloride salt is used, which is not easy to react with acid ions to form a precipitate, thereby not easily introducing new impurities, and the post-treatment process is also relatively simple.

[0018] In some optional embodiments, the mass of the chloride salt accounts for 10-15% of the mass of the acid solution.

[0019] In the above technical solution, the chloride salt in the acid solution is limited within a specific range, so that the acid solution has a suitable mass ratio of chloride salt, thereby more effectively removing heavy metal ions in the carbon material.

[0020] In some optional embodiments, during the stirring treatment under heating conditions, the treatment temperature is 50-80°C, and the treatment time is 4-8h.

[0021] In the above technical solution, the treatment temperature and the treatment time during the heating treatment are limited within specific ranges, so that the acid solution is soaked under more suitable conditions, thereby more thoroughly removing heavy metal ions in the carbon material.

[0022] In some optional embodiments, during the stirring treatment under heating conditions, the stirring speed is 100-300rpm.

[0023] In the above technical solution, the stirring speed during the heating treatment is limited within a specific range, so that the acid solution is soaked under more suitable conditions, thereby more thoroughly removing heavy metal ions in the carbon material.

[0024] In some optional embodiments, during the cleaning, the conductivity of the cleaning solution is less than 100μS / cm.

[0025] In the above technical solution, the upper limit of the conductivity of the last cleaning solution is limited within a specific range, i.e., the upper limit of the content of heavy metal ions in the carbon material is controlled within an extremely low range, which can further reduce the risk of secondary pollution in subsequent application. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 A process flow chart for recovering carbon material from waste battery negative electrodes and preparing it into an electrochemical cathode is provided. DETAILED DESCRIPTION

[0028] In order to make the purposes, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not indicated in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be purchased in the market are adopted.

[0029] It should be noted that, in the present application, "and / or", such as "feature 1 and / or feature 2", means "feature 1" alone, "feature 2" alone, or "feature 1" plus "feature 2".

[0030] In addition, in the description of the present application, unless otherwise specified, "multiple" in "one or more" means two or more; the range of "value a~value b" includes both end values "a" and "b", and "unit of measurement" in "value a~value b+unit of measurement" represents the "unit of measurement" of both "value a" and "value b".

[0031] At present, the graphite recovered from waste batteries is mainly prepared into battery negative electrodes for application, but the prepared batteries have the problem of rapid performance degradation, making it difficult to effectively utilize the graphite recovered from waste batteries.

[0032] The inventors found that although the corresponding battery of the graphite recovered from waste batteries has performance defects, the graphite can be prepared into an electrochemical cathode and used for wastewater treatment (electrochemical treatment is an important water treatment technology and is widely used in water treatment, and the corresponding electrochemical cathode usually uses graphite as the electrochemical cathode), which can realize the resource utilization of the graphite in waste batteries.

[0033] In addition, the inventors further found that the carbon material recovered from the negative electrode of waste batteries is prepared into an electrochemical cathode, and since the carbon material contains a small amount of conductive carbon black in addition to graphite, compared with the commercially available graphite prepared into an electrochemical cathode, the former has the advantage of higher water treatment efficiency.

[0034] The application of the carbon material recovered from the negative electrode of waste batteries in the embodiments of the present application in electrochemical wastewater treatment will be specifically described below.

[0035] The embodiments of the present application provide an application of a carbon material recovered from the negative electrode of waste batteries in electrochemical wastewater treatment, wherein the carbon material is prepared into an electrochemical cathode and used for electrochemical wastewater treatment.

[0036] It should be noted that the carbon material recovered from the negative electrode of waste batteries mainly exists in the form of graphite (the mass fraction is usually more than 90%), and also contains a small amount of conductive carbon black as a conductive agent (the mass fraction is usually 1-5%).

[0037] In the present application, the carbon material recovered from the negative electrode of the waste battery is prepared into an electrochemical cathode and used for wastewater treatment, which can provide a more reasonable new way for the resource utilization of graphite. In addition, compared with the preparation of an electrochemical cathode from commercially available graphite, the preparation of an electrochemical cathode from the carbon material recovered from the negative electrode of the waste battery has the advantage of higher water treatment efficiency.

[0038] As an example, the process of recovering the carbon material from the negative electrode of the waste battery and preparing the electrochemical cathode and using it for electrochemical wastewater treatment includes the following steps:

[0039] The carbon material precursor obtained from the negative electrode of the waste battery is provided; the carbon material precursor is sequentially subjected to crushing, acid soaking, solid-liquid separation and cleaning to obtain the carbon material; the carbon material and the binder are mixed, and the mixed slurry is coated on the surface of the conductive metal to obtain an electrochemical cathode intermediate; the electrochemical cathode intermediate is sequentially subjected to flattening and drying to obtain the electrochemical cathode; and the electrochemical cathode is applied to electrochemical wastewater treatment.

[0040] It should be noted that the carbon material precursor refers to the mixture of powders (particle size D50 is about 500 nm) after the negative electrode material (including graphite, conductive carbon black and binder) is scraped off from the negative electrode current collector and calcined, wherein the binder has been removed during the calcination stage (the binder can be removed after calcination, which is a conventional technical means, and will not be described in the embodiments of the present application). That is, the remaining mixed powders are a mixture of graphite and conductive carbon black, and a part of heavy metal ions (such as manganese, nickel, cobalt and copper) are also doped therein.

[0041] It should be noted that the related process of how to obtain the carbon material precursor will not be described in the embodiments of the present application, which is a conventional technical means.

[0042] In this embodiment, according to the specific preparation process provided in the embodiments of the present application, the carbon material recovered from the negative electrode of the waste battery can be prepared into an electrochemical cathode with high water treatment efficiency. The carbon material precursor is crushed to obtain carbon material particles with smaller particle size, so as to pursue higher specific surface area, so that the corresponding electrochemical cathode has higher water treatment efficiency, and the heavy metal ions in the carbon material can also be effectively removed. The acid soaking is to effectively separate the carbon material and the heavy metal ions (the presence of heavy metals can easily cause secondary pollution), so as to reduce the risk of secondary pollution in the subsequent application process. Coating the mixed slurry on the surface of the conductive metal for preparing the electrochemical cathode can reduce the amount of carbon material used, thereby saving costs. In addition, the electrochemical cathode is prepared by coating and curing, which has the advantages of simple and efficient preparation process.

[0043] As an example, in the process of crushing, the particle size D50 of the carbon material precursor is 100-200 nm, for example, but not limited to, any one of the particle size D50 of 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm and 200 nm or a range value between any two of them.

[0044] In this embodiment, the particle size of the carbon material precursor is controlled within a certain range, so that the particles have a more ideal specific surface area, thereby making the electrochemical cathode have a higher water treatment efficiency, and at the same time, the heavy metal ions in the carbon material can be more effectively removed.

[0045] It should be noted that the type of equipment used in the crushing stage is not limited, and can be set according to conventional selection in the art, for example, it can be a ball mill or a sand mill, and in the embodiments of the present application, a ball mill is taken as an example, and the corresponding parameter conditions are not limited, as long as it can be ground to a predetermined particle size.

[0046] As an example, the process of soaking in acid solution includes the following steps: transferring the crushed carbon material precursor into the acid solution and stirring under heating conditions.

[0047] In this embodiment, the process of soaking in acid solution is carried out under heating conditions, which can make the heavy metal ions and the carbon material more easily and efficiently separated, so as to more thoroughly remove the heavy metal ions in the carbon material, thereby further reducing the risk of secondary pollution in the subsequent application process.

[0048] As an example, the acid solution includes at least one of nitric acid, phosphoric acid and sulfuric acid.

[0049] In this embodiment, the technical solution of the present application is applicable to the above-mentioned various types of acid solution, and can provide more implementable schemes, thereby facilitating the popularization and application of the technical solution of the present application.

[0050] It should be noted that when the acid solution system is mixed acid, the amount of different types of acid solution is not limited, and can be adjusted according to actual needs.

[0051] As an example, the acid solution also includes a chloride salt.

[0052] In this embodiment, the chloride salt is added to the acid solution, and by virtue of the corrosiveness of the chloride ions, the heavy metal ions in the carbon material can be more thoroughly removed, thereby further reducing the risk of secondary pollution in the subsequent application process.

[0053] As an example, the chloride salt includes potassium chloride and / or sodium chloride.

[0054] In this embodiment, a specific kind of chloride salt is used, which is not easy to react with the acid radical ion to form a precipitate, so as not to easily introduce new impurities, and the post-processing process is also relatively simple.

[0055] It can be understood that the amount of chloride salt is closely related to the separation and removal effect of heavy metal ions.

[0056] As an example, the mass of the chloride salt accounts for 10-15% of the mass of the acid solution, for example, but not limited to, any one of the mass ratios of 10%, 11%, 12%, 13%, 14%, and 15%, or a range value between any two of them.

[0057] In this embodiment, the chloride salt in the acid solution is limited within a specific range, so that the acid solution has a suitable mass ratio of chloride salt, thereby more effectively removing heavy metal ions in the carbon material.

[0058] It can be understood that the control of relevant parameters (such as treatment temperature, treatment time, and stirring speed, etc.) during the heating and stirring treatment process is closely related to the separation and removal effect of heavy metal ions.

[0059] As an example, during the stirring treatment process under heating conditions, the treatment temperature is 50-80℃, for example, but not limited to, any one of the point values of 50℃, 60℃, 70℃, and 80℃, or a range value between any two of them; the treatment time is 4-8h, for example, but not limited to, any one of the point values of 4h, 5h, 6h, 7h, and 8h, or a range value between any two of them.

[0060] In this embodiment, the treatment temperature and the treatment time during the heating treatment process are respectively limited within a specific range, so that the acid solution is soaked under a more suitable condition, so as to more thoroughly remove heavy metal ions in the carbon material.

[0061] As an example, during the stirring treatment process under heating conditions, the stirring speed is 100-300rpm, for example, but not limited to, any one of the point values of 100rpm, 150rpm, 200rpm, 250rpm, and 300rpm, or a range value between any two of them.

[0062] In this embodiment, the stirring speed during the heating treatment process is limited within a specific range, so that the acid solution is soaked under a more suitable condition, so as to more thoroughly remove heavy metal ions in the carbon material.

[0063] As an example, during the cleaning process, the conductivity of the cleaning solution is less than 100μS / cm.

[0064] In this embodiment, the upper limit of the conductivity of the last cleaning liquid is limited in a specific range, i.e., the upper limit of the content of heavy metal ions in the carbon material is controlled in an extremely low range, which can further reduce the risk of secondary pollution in the subsequent application process.

[0065] It should be noted that the solid-liquid separation method is not limited, for example, it can be centrifugal separation or filtration separation.

[0066] It should be noted that in the process of mixing the carbon material and the binder and coating the mixed slurry on the surface of the conductive metal to obtain the electrochemical cathode intermediate, the type of the binder is not limited and can be set according to the conventional selection in the art.

[0067] As an example, the binder includes polyvinyl alcohol, and the ratio of the mass of the binder to the mass of the carbon material is (1-2):20.

[0068] As an example, in the process of mixing the carbon material and the binder, the stirring time is 20-30 min, and the stirring speed is 1000-1500 r / min.

[0069] It can be understood that in order to make the binder and the carbon material mix more uniformly, the conditions of the mixing process can be optimized.

[0070] As an example, the mixing process is carried out under heating conditions, and the treatment temperature is 60-75℃.

[0071] It can be understood that in the process of leveling the electrochemical cathode intermediate, the thickness of the corresponding carbon material coating is not limited and can be adjusted according to actual needs, for example, the thickness of the carbon material after leveling is 0.1-1 mm.

[0072] It should be noted that in the drying process, the treatment temperature and the treatment time are not limited, for example, the treatment temperature is 100-120℃, and the treatment time is 4-8 h.

[0073] It should be noted that in the process of assembling the electrochemical device, the electrochemical anode can be set according to the conventional selection, for example, the electrochemical anode is a ruthenium iridium titanium electrode.

[0074] As an example, the process flow diagram of recovering the carbon material from the waste battery and preparing the electrochemical cathode is exemplarily shown in Figure 1 .

[0075] The features and performance of the present application are further described in detail below in conjunction with the examples.

[0076] Example 1

[0077] The embodiment of the present application provides a method for recycling carbon materials from waste batteries and preparing the carbon materials into electrochemical cathodes, which comprises the following steps:

[0078] The carbon material precursor obtained from the negative electrode of the waste battery is provided; the carbon material precursor is crushed by using a ball mill until the particle size D50 of the carbon material precursor is 150 nm; the carbon material precursor after crushing is soaked under the conditions of stirring and heating by using acid liquor, wherein the acid liquor is a mixed system of sulfuric acid and nitric acid, the volume ratio of the two is 1:1, and the acid liquor further contains 12% of sodium chloride in terms of mass percentage, the treatment temperature is 70 DEG C, the treatment time is 6h, and the stirring speed is 200 rpm; the solid-liquid system after soaking in the acid liquor is separated by using a filtration separation method; the solid particles after filtration are cleaned by using distilled water until the conductivity of the cleaning liquid is less than 100 mu S / cm; the carbon material and polyvinyl alcohol are mixed and stirred under heating conditions, and the mixed slurry is coated on the surface of an aluminum foil to obtain an electrochemical cathode intermediate, wherein the mass ratio of the polyvinyl alcohol to the carbon material is 1:10, the treatment temperature is 70 DEG C, the treatment time is 25 min, and the stirring speed is 1000 r / min; the aluminum foil after coating the slurry is flattened by using a flattening roller, so that the thickness size of the corresponding coating layer of the flattened carbon material is 0.5 mm, and then the flattened aluminum foil is dried at 110 DEG C for 4h to obtain an electrochemical cathode.

[0079] Example 2

[0080] The embodiment of the present application provides a method for recycling carbon materials from waste batteries and preparing the carbon materials into electrochemical cathodes, which is only different from the embodiment 1 in that the acid liquor does not contain sodium chloride.

[0081] Comparative Example 1

[0082] The embodiment of the present application provides a method for preparing an electrochemical cathode, which comprises the following steps:

[0083] The commercially available graphite and polyvinyl alcohol are mixed and stirred under heating conditions, and the mixed slurry is coated on the surface of an aluminum foil to obtain an electrochemical cathode intermediate, wherein the mass ratio of the polyvinyl alcohol to the graphite is 1:10, the treatment temperature is 70 DEG C, the treatment time is 25 min, and the stirring speed is 1000 rpm; the aluminum foil after coating the slurry is flattened by using a flattening roller, so that the thickness size of the corresponding coating layer of the flattened graphite is 0.5 mm, and then the flattened aluminum foil is dried at 110 DEG C for 4h to obtain an electrochemical cathode.

[0084] Test Example 1

[0085] Content test of heavy metal ions in carbon materials

[0086] Test method

[0087] The carbon materials obtained in Example 1 and Example 2 were numbered respectively, and then each sample was digested into a test solution, and then the heavy metal content in each test solution was tested by ICP equipment.

[0088] Table 1: Test results of heavy metal content in carbon materials

[0089] Sample Heavy metal content (%) Example 1 0.01 Example 2 0.07

[0090] Referring to Table 1, according to the test results of Example 1 and Example 2, the acid liquid contains sodium chloride, compared with the acid liquid without sodium chloride, the former can more effectively separate and remove heavy metal ions from the carbon material by the corrosive nature of chloride ions, so that the recovered carbon material has less heavy metal ions.

[0091] Experimental Example 2

[0092] Test of water treatment capacity of electrochemical cathode

[0093] Test method

[0094] The electrochemical cathodes corresponding to Example 1 and Comparative Example 1 were respectively assembled into electrochemical treatment equipment, wherein the electrochemical anode was a ruthenium iridium titanium electrode, and then each sample was used to treat the filtrate wastewater after biological treatment twice, wherein the initial COD of the wastewater was 165 mg / L, the initial nitrogen and oxygen content was 16.5 mg / L, the initial color was 31, and the current density of the electrochemical treatment equipment was 15 mA / cm 2 , the treatment time was 60 min, and the specific results are as follows in Table 2.

[0095] Table 2: Water quality statistics of filtrate wastewater after electrochemical treatment

[0096] Sample COD content (mg / L) Ammonia nitrogen content (mg / L) Color Example 1-1 46 0.3 2.3 Example 1-2 39 0.5 1.8 Comparative Example 1-1 78 0.9 2.8 Comparative Example 1-2 75 0.9 2.6

[0097] Referring to Table 2, according to the test results of Example 1 and Comparative Example 1, the carbon material (i.e. the mixed system of graphite and conductive carbon black) provided by the present application is prepared into an electrochemical cathode, which has a more excellent wastewater treatment capacity compared with the electrochemical cathode prepared by using a commercially available single graphite.

[0098] Experimental Example 3

[0099] Test of water treatment capacity of electrochemical cathode

[0100] Test method

[0101] The electrochemical cathode corresponding to Example 1 and Comparative Example 1 was respectively assembled into an electrochemical treatment device, wherein the electrochemical anode was a ruthenium iridium titanium electrode, and then the sulfur black pigment cleaning wastewater was subjected to two decolorization treatments by using each sample, wherein the initial COD of the wastewater was 232 mg / L, the current density of the electrochemical treatment device was 15 mA / cm 2 , and the treatment time was 30 min. The specific results are shown in Table 3.

[0102] Table 3: Water quality statistics of wastewater after electrochemical treatment

[0103] Sample COD content (mg / L) Decolorization rate (%) Example 1-1 64 97.6 Example 1-2 60 97.7 Comparative Example 1-1 93 92.6 Comparative Example 1-2 92 92.5

[0104] Referring to Table 3, it can be seen from the test results of Example 1 and Comparative Example 1 that the carbon material (i.e., the mixed system of graphite and conductive carbon black) provided by the present application has a more excellent wastewater treatment capacity compared with the electrochemical cathode prepared by using the commercially available single graphite.

[0105] The above-described examples are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

Claims

1. An application of carbon materials recovered from the negative electrode of waste batteries in electrochemical wastewater treatment, characterized in that, The carbon material was prepared into an electrochemical cathode and used for electrochemical wastewater treatment; The process of recovering the carbon material from the negative electrode of a spent battery, preparing it into an electrochemical cathode, and using it for electrochemical wastewater treatment includes the following steps: Provide carbon material precursors obtained from the negative electrodes of spent batteries; The carbon material precursor is sequentially subjected to crushing, acid soaking, solid-liquid separation and washing to obtain the carbon material. The carbon material and binder are mixed and the mixed slurry is coated onto a conductive metal surface to obtain an electrochemical cathode intermediate. The electrochemical cathode intermediate is sequentially leveled and dried to obtain the electrochemical cathode; and the electrochemical cathode is applied to electrochemical wastewater treatment. The acid soaking process includes the following steps: transferring the crushed carbon material precursor into the acid solution and stirring it under heating conditions; The acid solution also includes chloride salts.

2. The application according to claim 1, characterized in that, During the crushing process, the particle size D50 of the carbon material precursor is reduced to 100~200 nm.

3. The application according to claim 1, characterized in that, The chloride salt includes potassium chloride and / or sodium chloride.

4. The application according to claim 1, characterized in that, In the acid solution, the chloride ion salt accounts for 10-15% of the mass of the acid solution.

5. The application according to claim 1, characterized in that, During the stirring process under heating conditions, the processing temperature is 50~80℃ and the processing time is 4~8 h.

6. The application according to claim 1, characterized in that, During the stirring process under heating conditions, the stirring speed is 100~300 rpm.

7. The application according to claim 1, characterized in that, During the cleaning process, the electrical conductivity of the cleaning solution is reduced to less than 100 μS / cm.

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