CN115285983A - Method for recycling cathode retired graphite and method for modifying manganese oxide by using cathode retired graphite - Google Patents
Method for recycling cathode retired graphite and method for modifying manganese oxide by using cathode retired graphite Download PDFInfo
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- 239000010439 graphite Substances 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 50
- 238000004064 recycling Methods 0.000 title claims abstract description 14
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 title abstract description 10
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 67
- 239000003054 catalyst Substances 0.000 claims abstract description 34
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- 238000010438 heat treatment Methods 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
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- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 39
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/184—Preparation
- C01B32/19—Preparation by exfoliation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8678—Removing components of undefined structure
- B01D53/8687—Organic components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/32—Manganese, technetium or rhenium
- B01J23/34—Manganese
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/10—Heat treatment in the presence of water, e.g. steam
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/708—Volatile organic compounds V.O.C.'s
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
Abstract
The invention relates to a method for recycling cathode retired graphite and a method for modifying manganese oxide by using the same. On one hand, the method solves the problem of resource recycling of a large amount of lithium battery negative electrode graphite in the current industrial application, and the prepared snowflake graphene is special in appearance and excellent in performance. On the other hand, the improved and regenerated graphene is an excellent modifier, and the prepared rGO @ alpha-MnO is 2 The catalyst overcomes the defect of low catalytic performance of transition metal oxideCompared with the common alpha-MnO, the method has the defects of difficult synthesis, agglomeration and regeneration 2 The performance is greatly improved.
Description
Technical Field
The invention belongs to the technical field of catalyst preparation, and relates to a method for recycling cathode retired graphite and a method for modifying manganese oxide by using the same.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
Decommissioned graphite typically contains contaminants originating from the electrolyte, binder, solid electrolyte interface film (SEI), and copper foil such that it is difficult to utilize directly. How to reuse a large amount of resources of lithium battery negative electrode graphite in industrial application is a technical problem which needs to be solved urgently. Generally, the intercalation and deintercalation of lithium ions during the charge and discharge of a lithium battery can cause the distance between graphite layers to be enlarged, the van der waals force between the layers is weakened, and the graphite is easier to form a flaky carbon nano material compared with common graphite and is a high-quality carbon source for synthesizing graphene. The problems of impurity removal and recycling of the retired graphite cathode can be perfectly solved by means of high-energy microwaves. On one hand, the interlayer pollutants generate an overheating effect and are rapidly heated and gasified, so that the impurity removal of the retired graphite is realized; on the other hand, the gasified product is released instantly, the graphite interlayer spacing is enlarged, and then the puffing effect is generated, and the generation of high-quality graphene is facilitated. The graphene synthesized by the method theoretically has larger interlayer spacing and more defects, and can be large when compounded with transition metal oxideGreatly improves the electron transfer rate, reduces the particle size of the nano material and has wide application prospect. Further, high-quality graphene and alpha-MnO are utilized 2 The composite catalyst can effectively overcome the defects of low performance, synthesis agglomeration and difficult regeneration of the current VOCs catalyst, really realizes the treatment of wastes with processes of wastes against one another and realizes the reasonable utilization of resources.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for recycling the retired graphite of the negative electrode and a method for modifying manganese oxide by using the retired graphite of the negative electrode. Firstly, the invention solves the problem of resource recycling of a large amount of lithium battery negative electrode graphite in the current industrial application, and provides a high-energy microwave thermal shock-improved Hummers method for preparing snowflake graphene, so that the prepared graphene has special appearance and excellent performance, and is an excellent modifier. Then, rGO @ alpha-MnO preparation by anchoring-nucleation growth process 2 A catalyst. In one aspect, the graphene oxide oxygen-containing functional group is used as Mn 2+ The anchoring site can improve the catalyst dispersibility, effectively inhibit the particle agglomeration and reduce the particle size. On the other hand, the snowflake graphene is used as an electron transmission channel, the electron transfer characteristic of the catalyst can be effectively improved, the oxygen vacancy regeneration is promoted, and the synthesized rGO @ alpha-MnO 2 The catalyst can realize the high-efficiency degradation of VOCs at low temperature.
Specifically, the technical scheme of the invention is as follows:
in the first aspect of the invention, a method for recycling the retired graphite of the negative electrode is provided, a regeneration method of a high-energy microwave repeated impact-improved Hummers method is originally created, and a snowflake-shaped graphene oxide suspension is finally prepared.
Specifically, the method comprises the following steps:
firstly, placing negative graphite obtained by disassembling completely discharged waste batteries into a NaOH solution and stirring; then, filtering, washing and drying; placing graphite powder in a quartz reactor for microwave impact, introducing Ar under a closed condition, and adjusting the power and temperature of a solid microwave source; and after the microwave impact cycle is repeated for many times, treating the graphite powder by adopting an improved Hummers method to obtain the graphene oxide turbid liquid.
Further, the concentration of the NaOH solution is 2-4mol/L.
Furthermore, the flow rate of introducing Ar into each 1g of retired graphite is 300-1000mL/min.
Furthermore, the power of the solid-state microwave source is 1000W, and the upper temperature limit is 1200 ℃.
Further, the impact mode is that after the upper limit temperature is reached once, the cooling is carried out for 30s, then the temperature is continuously raised, and the circulation is carried out for 5-20 times in total; the graphite sample was then removed and placed in a dry box for future use.
Further, the graphite powder is processed by an improved Hummers method to obtain the graphene oxide suspension. First, the expanded graphite subjected to microwave treatment was placed in a beaker, to which concentrated H was added 2 SO 4 (98%) and continuously stirring for 30min in an ice bath, wherein the solid-to-liquid ratio of the expanded graphite to the concentrated sulfuric acid is 1: (20-40) in units of g: and (mL). While stirring, H was added dropwise to the solution 3 PO 4 The volume ratio of concentrated sulfuric acid to phosphoric acid is (6-8): 1. then, KMnO is added 4 Adding the solid into the mixture ten times at time intervals of 5-7min each time 4 The mass ratio of the graphite to the expanded graphite is 6:1. and then, stirring for 2 hours respectively at the temperature of 35 ℃ and in an ice bath, adding a proper amount of deionized water after stirring is finished, heating to 80 ℃, and continuing stirring for 1 hour. Finally, H was added dropwise after completion of stirring 2 O 2 (30%) desired concentrated H 2 SO 4 And H 2 O 2 The volume ratio of (1-3): and 1, washing with water for 5-7 times to obtain a graphene oxide suspension.
In the second aspect of the invention, the snowflake graphene suspension prepared by the method is freeze-dried to obtain a snowflake graphene solid.
In a third aspect of the invention, a snowflake graphene modified alpha-MnO is provided 2 A method of making the catalyst. By virtue of the good properties of graphene, with MnO 2 The performance of the prepared catalyst is compared with that of the common MnO 2 The catalytic performance of the catalyst is greatly improved.
The method specifically comprises the following steps:
suspending the graphene oxidePlacing the solution in a container, adding deionized water, and adding MnSO into the solution 4 ·H 2 O, stirring until the solid is dissolved; mixing KMnO 4 Dropwise adding the solution into the solution, and continuously stirring for 1-2h to complete the primary reaction; after the solution reaction is stopped, heating the solution at 150 ℃ for 12h to complete the nucleation process; taking out the precipitate after hydrothermal treatment, washing and drying to obtain snowflake graphene modified alpha-MnO 2 A catalyst.
Furthermore, the concentration of the graphene oxide suspension is 1-3mg/mL.
Further, graphene oxide and MnSO 4 ·H 2 The mass ratio of O is (1-5): 53.
further, the volume of deionized water filled is such that the total volume of the solution is 50% of the volume of the inner liner of the reaction vessel.
Further, KMnO required for the reaction 4 With MnSO 4 ·H 2 The molar ratio of O should be kept between (8-9): 3.
in the fourth aspect of the invention, the snowflake graphene modified alpha-MnO prepared by the method is provided 2 A catalyst.
In terms of the operating principle and structural composition of a negative electrode for a lithium battery, the retired graphite generally contains contaminants originating from an electrolyte, a binder, a solid electrolyte interface film (SEI), and a copper foil, so that it is difficult to directly utilize. However, as compared to natural flake graphite, as intercalation and deintercalation of lithium ions during charge and discharge of a battery causes an expansion of graphite interlayer spacing, van der waals force between layers is weakened, and a sheet-like and sp2 hybridized carbon nanomaterial is more easily formed. At the same time, the attached oxygen-containing groups can prevent interlayer polymerization from occurring. Therefore, the intrinsic structure with expanded space between the retired graphite layers enables the retired graphite layers to be intercalated more easily, and the retired graphite layers serving as raw materials for preparing graphene or graphene oxide have inherent advantages.
The method selects the decommissioned graphite cathode as a graphene carbon source, finishes graphite puffing by repeatedly impacting the decommissioned graphite with the aid of high-energy microwaves, and synthesizes the snowflake graphene oxide by improving a Hummers method. Meanwhile, alpha-MnO is generated in situ on graphene oxide by adopting a hydrothermal method 2 And (3) a nano catalyst. By means of improvements madeGraphene and alpha-MnO 2 An electron transfer channel is formed, the electron transfer capability is improved, the oxygen vacancy regeneration is accelerated, and the catalyst performance is further improved.
One or more technical schemes in the invention have the following beneficial effects:
(1) The invention realizes the regeneration of the cathode retired graphite to prepare the high-performance graphene material. Through the repeated impact of unique high-energy microwaves, the microwaves act on the decommissioned graphite to induce rapid temperature rise, and meanwhile, the overheating effect in the form of local hot spots and arc plasmas is generated to rapidly gasify impurities among layers, so that the impurity removal and stripping of the decommissioned negative electrode graphite are realized. Meanwhile, by means of an improved Hummers method, the expanded graphite is oxidized and recycled, and a new idea is provided for resource utilization of the graphite.
(2) The invention provides a method for improving graphene. By improving the carbon source, high-quality snowflake graphene with excellent performance and special appearance is synthesized. Compared with the common graphene, the prepared snowflake graphene has more edge defects and larger interlayer spacing, and can improve the electron transfer capability and the oxygen vacancy regeneration capability of the catalyst after being compounded with the transition metal oxide.
(3) The invention provides rGO @ MnO 2 A method for applying the composite material in the field of catalysis. Compared with common MnO, the prepared catalyst 2 The structure is optimized, the electron transmission performance is improved, and the toluene degradation performance is greatly improved. Meanwhile, the catalytic performance of the graphene under high humidity is greatly improved through modification of the graphene, and efficient degradation of toluene under high humidity is realized.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a scanning electron micrograph of ex-service graphite as it is;
FIG. 3 is a scanning electron micrograph of exfoliated expanded graphite after repeated high energy microwave impingement;
FIG. 4 is a scanning electron micrograph of snowflake graphene prepared by a modified Hummers method;
FIG. 5 is an enlarged view of a snowflake graphene solid scanning electron microscope prepared by a modified Hummers method;
FIG. 6 is a graph showing the performance of each catalyst in catalytic oxidation of toluene in a dry environment;
FIG. 7 is a graph showing the performance of each catalyst in catalytic oxidation of toluene in a wet environment.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
Example 1
A method for preparing snowflake graphene by regeneration of retired negative electrode graphite comprises the following steps:
firstly, negative electrode graphite obtained by disassembling completely discharged waste batteries is placed in 2L of NaOH solution (2 mol/L) and stirred for 1 hour to remove part of DMF impurities. Subsequently, the graphite in the solution was filtered, washed to a solution PH =7 and dried at 90 ℃ for 12h. Subsequently, 0.5g of graphite powder after alkaline leaching was weighed, placed in a quartz reactor, equipped with an infrared thermocouple, and then charged with Ar (300 mL/min) under a closed condition. Subsequently, the power of the solid-state microwave source was adjusted to 1000W, and the upper temperature limit was 1200 ℃. The impact mode is that after the upper limit temperature is reached once, the cooling is carried out for 30s, then the temperature is continuously increased, and the total 5-20 times of circulation are carried out. The graphite sample was removed after each impact and placed in a dry box for future use. And (3) taking a proper amount of pretreated expanded graphite, placing the expanded graphite in a beaker, and treating by adopting an improved Hummers method to obtain the graphene oxide turbid liquid. The procedure is as follows, first, the microwave-treated expanded graphite is taken up in a beaker, to which concentrated H is added 2 SO 4 (98%) and continuously stirring for 30min in an ice bath, wherein the solid-to-liquid ratio of the expanded graphite to the concentrated sulfuric acid is 1:30, unit is g: and (mL). While stirring, H was added dropwise to the solution 3 PO 4 The volume ratio of phosphoric acid to concentrated sulfuric acid is 1:7.5. then, the user can use the device to perform the operation,mixing KMnO 4 Adding the solid into the mixed solution ten times, wherein each time interval is 6min 4 The mass ratio of the graphite to the expanded graphite is 6:1. and then, stirring for 2 hours respectively at the temperature of 35 ℃ and in an ice bath, adding a proper amount of deionized water after stirring is finished, heating to 80 ℃, and continuing stirring for 1 hour. Finally, H is added dropwise after stirring is completed again 2 O 2 (30%) desired concentrated H 2 SO 4 And H 2 O 2 The volume ratio is 1: and 3, washing with water for 5-7 times to obtain a graphene oxide suspension. The concentration of the graphene oxide suspension is set to be 2mg/mL for standby. And (4) freeze-drying the graphene oxide turbid liquid to obtain the snowflake graphene solid.
Example 2
Preparation of rGO @ alpha-MnO by regeneration of retired negative electrode graphite 2 A method for preparing a high efficiency VOCs catalyst comprising:
the preparation process diagram is shown in figure 1. Firstly, when the volume of the hydrothermal kettle is selected to be 100ml, 5ml and 10ml of graphene suspension prepared in example 1 are respectively measured and placed in a beaker, and different amounts of deionized water are added, so that the volume of the solution is set to be 50ml. Then, mnSO was added to the solution 4 ·H 2 O solid, stirring until the solid is dissolved, and oxidizing the graphene and the MnSO 4 ·H 2 The mass ratio of O is 1:53 and 2:53. subsequently, KMnO was weighed 4 The solid is prepared into a solution, slowly and dropwise added into the solution, and stirring is continued for 30min, wherein KMnO required by the reaction is prepared 4 With MnSO 4 ·H 2 The molar ratio of O should be kept between 8:3. after the solution reaction is stopped, the solution is respectively placed in 100ml polytetrafluoroethylene tanks and heated for 12h at 150 ℃. The hydrothermal precipitate was removed, washed three times with deionized water, dried at 110 ℃ for 12h and the solids were each labeled as 1% rGO @ alpha-MnO 2 、2％rGO@α-MnO 2 . For comparative testing, 50ml of deionized water was measured and the procedure repeated, and the resulting sample was labeled as α -MnO 2 . The dosage of the medicine required by the preparation process is increased proportionally according to the increase of the volume of the reaction container.
Scanning electron microscope test analysis in preparation process of snowflake graphene
As shown in fig. 2, the graphite powder after the alkaline leaching treatment had rough and uneven surfaces and particles of different sizes adhered thereto, and it was analyzed that the graphite powder was a waste battery electrolyte or an untreated clean KOH residue. Graphite powder is compact in morphology as is, and shows a typical multilayer stacking phenomenon of graphite layers.
As shown in fig. 3, in example 1, the characteristics of the graphite powder were greatly changed after ten times of microwave impact. Firstly, a compact graphite structure is stripped into a plurality of graphite sheets, the spacing between the graphite layers is different, and wrinkles exist on the surfaces of the graphite layers. Then, the graphite layer surface was smooth and remained as it was and disappeared. Analysis shows that after the microwave repeated impact for ten times, graphite powder solid is stripped, a graphite layer becomes thin, and impurities on the surface of graphite are removed by multiple impacts, so that the preparation of graphene is facilitated.
As shown in fig. 4, the snowflake graphene prepared by the modified Hummers method exhibits a single-layer thin snowflake morphology. As shown in fig. 5, the snowflake graphene surface has more wrinkles, which is a typical graphene morphology, observed by magnification.
And (3) testing the performance of the catalyst:
catalyst test preparation: 0.2 to 0.4g of the catalyst powder obtained in example 2 was tableted and sieved to 40 to 60 mesh, and packed in a quartz reactor and fixed using double-layered quartz wool. The reaction was carried out using 250-500mL/min of synthesis air carrying the vaporized toluene into the reactor, with the toluene concentration set at 300ppm. Meanwhile, the water vapor generating devices are connected in parallel, and the atmosphere humidity value is synchronously controlled. The reactor is placed in a vertical tube furnace, and the tube furnace is set with a program temperature rise for heating the catalyst. At the reactor outlet, a gas chromatograph was equipped for off-gas detection and toluene conversion was calculated by the following formula:
wherein [ Toluene] in and[Toluene] out Representing the inlet toluene concentration and the outlet toluene concentration, respectively.
Relative humidity is shown in FIG. 6A graphical representation of toluene conversion at 25% and a space velocity of 80000 ml/(gh). First, 2% rGO- α -MnO 2 Exhibits optimum catalytic performance with a T90 of about 166.8 ℃ 1% rGO-alpha-MnO 2 Due to the fact that the doping amount of the graphene is small, the performance is relatively poor. Secondly, compare 1% scale rGO @ alpha-MnO 2 、α-MnO 2 The catalyst performance of the composite snowflake graphene is greatly improved, which proves that the electron transmission performance is effectively improved by the composite snowflake graphene, and the catalyst performance is further improved.
FIG. 7 is a graph showing the toluene conversion under wet conditions (RH = 80-85%) at a space velocity of 80000 ml/(gh). In one aspect, the performance of the improved catalyst in a wet environment is maintained, which demonstrates that rGO @ alpha-MnO 2 Has higher hydrophobic property and can adapt to severe catalytic atmosphere. On the other hand, the catalyst performance of the snowflake graphene with the doping amount of 2% is better than that of the catalyst with the doping amount of 1%, which proves that the snowflake graphene plays an important role in resisting a high humidity environment.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A method for recycling cathode retired graphite is characterized by comprising the following steps:
firstly, placing negative graphite obtained by disassembling completely discharged waste batteries into a NaOH solution and stirring; then, filtering, washing and drying; placing the obtained graphite powder in a quartz reactor for microwave impact, introducing Ar under a closed condition, and adjusting the power and temperature of a solid microwave source; and after the microwave impact cycle is repeated for many times, treating the graphite powder by adopting an improved Hummers method to obtain the graphene oxide turbid liquid.
2. The method for recycling the cathode retired graphite, according to claim 1, wherein the concentration of the NaOH solution is 2-4mol/L.
3. The method for recycling the cathode decommissioned graphite according to claim 1, wherein the flow rate of Ar fed is required to be 300-1000mL/min per 1g of decommissioned graphite.
4. The method for recycling the cathode retired graphite according to claim 1, wherein the power of the solid microwave source is 1000W, and the upper temperature limit is 1200 ℃; the impact mode is that after the upper limit temperature is reached once, the cooling is carried out for 30s, then the temperature is continuously raised, and the total 5-20 times of circulation are carried out; taking out the expanded graphite powder after each impact, and placing the expanded graphite powder in a drying box for later use;
or, the specific steps of the improved Hummers method are as follows: mixing and stirring the expanded graphite subjected to microwave treatment and concentrated sulfuric acid, wherein the solid-liquid ratio is 1: (20-40) in units of g: mL; while stirring, H was added dropwise to the solution 3 PO 4 The volume ratio of concentrated sulfuric acid to phosphoric acid is (6-8): 1; then, KMnO is added 4 Adding the solid into the mixed solution for ten times at time interval of 5-7min, KMnO 4 The mass ratio of the graphite to the expanded graphite is 6:1; then, stirring for 2 hours respectively in an ice bath at 35 ℃, adding a proper amount of deionized water after stirring, heating to 80 ℃, and continuing stirring for 1 hour; finally, H was added dropwise after completion of stirring 2 O 2 (30%) desired concentrated H 2 SO 4 And H 2 O 2 The volume ratio of (1-3): and 1, washing with water for 5-7 times to obtain a graphene oxide suspension with the concentration of 1-3mg/mL.
5. The graphene oxide suspension prepared by the method for recycling the cathode retired graphite according to any one of the preceding claims.
6. Snowflake graphene modified alpha-MnO 2 The method for preparing the catalyst is characterized by comprising the following steps:
placing the graphene oxide suspension of claim 5 in a container, and adding deionized waterWater, followed by addition of MnSO to the solution 4 ·H 2 O, stirring until the solid is dissolved; mixing KMnO 4 Dropwise adding the solution into the solution, and continuously stirring for 1-2h to complete the primary reaction; after the solution stops reacting, heating the solution at 150 ℃ for 12h to complete the nucleation process; taking out the precipitate after hydrothermal treatment, washing and drying to obtain snowflake graphene modified alpha-MnO 2 A catalyst.
7. The negative retired graphene modified alpha-MnO of claim 6 2 The method of the catalyst is characterized in that the dosage of the graphene oxide turbid liquid is determined according to the graphene oxide and MnSO 4 ·H 2 The mass ratio of O is (1-5): 53.
8. the negative retired graphene modified alpha-MnO of claim 6 2 The method for preparing the catalyst is characterized in that the deionized water is used in an amount which enables the total volume of the reaction solution to reach 50% of the volume of the reaction kettle.
9. The negative electrode retired graphene modified alpha-MnO of claim 6 2 A process for preparing the catalyst, characterized in that the KMnO required for the reaction is used 4 With MnSO 4 ·H 2 The molar ratio of O should be kept between (8-9): 3.
10. negative electrode retired graphene modified alpha-MnO prepared by the method of any one of claims 6-9 2 A catalyst.
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