Graphene carbon negative electrode material and preparation method and application thereof

Abstract

The application discloses a kind of graphene carbon negative electrode material and its preparation method and application, belong to lithium ion battery negative electrode material technical field, by the metal ion of cerium nitrate and the 2,5-dihydroxy terephthalic acid grafted on the surface of conductive core-shell microsphere occurs coordination reaction and generates metal framework, and polystyrene nanometer microsphere is a kind of non-polar polymer, solubility is higher in DMF, using this feature can be removed as sacrificial template, obtain conductive double-shell hollow microsphere powder;By sulfonated graphene, conductive core-shell microsphere and metal framework build three-dimensional conductive network to increase conductivity, promote lithium ion fast transmission, and the hollow structure of conductive core-shell microsphere and the gap between metal framework shell layer can buffer volume expansion in charge and discharge process, and cerium metal ion in metal framework has excellent corrosion resistance, can avoid that electrode material is corroded by the component in electrolyte, guarantee the service life of negative electrode material.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material technology, specifically a graphene carbon anode material and its preparation method and application. Background Technology

[0002] Graphene is an attractive energy storage material due to its low cost and simple synthesis. It is a nanomaterial with excellent electrical conductivity and high mechanical strength, and has wide applications in new energy devices such as lithium-ion batteries, metal-air batteries, and fuel cells. Using graphene as a raw material, its large conjugated structure, rich microstructure, and large specific surface area, along with its high modifiability, abundant pores, excellent physicochemical stability, tunable pore size, and low thermal conductivity, have attracted widespread attention from researchers. However, graphene is prone to aggregation, which can affect the specific surface area and electrochemical performance of electrode materials. Combining graphene with porous carbon materials can effectively leverage the advantages of both.

[0003] Chinese patent announcement CN113113574B discloses a method for preparing graphene-modified silicon-carbon anode materials. This method uses hydrophilic silicone oil as a modifier and crosslinking agent for SiOx and carbon materials. After stepwise modification, liquid-phase mixing is performed to improve the bonding between SiOx and carbon material particles and graphene oxide. However, in this scheme, graphene oxide is prone to agglomeration and excessive stacking of sheets. Liquid-phase mixing alone does not involve chemical bonding, and cannot effectively guarantee the bonding between graphene oxide and other materials.

[0004] Introducing specific functional groups into the surface of graphene oxide through chemical grafting can significantly enhance its dispersibility and increase its bonding strength with various materials. Chinese patent announcement CN117263174B discloses a sulfonic acid graphene electrode material and its synthesis method. This method introduces sulfonic acid into graphene sheets to avoid excessive stacking of sheets and overcomes the defects such as small specific surface area of ​​graphene. However, the incorporation of sulfonic acid groups will cause the destruction of some of the conjugated structure of graphene, break the original π-π conjugated system, reduce conductivity, reduce mechanical stability, and hinder lithium electron transport, thereby affecting the performance of lithium batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene carbon anode material, its preparation method, and its application. A metal framework is generated by the coordination reaction of cerium nitrate metal ions with 2,5-dihydroxyterephthalic acid grafted onto the surface of conductive core-shell microspheres. Polystyrene nanospheres are a non-polar polymer with high solubility in DMF, which can be used as a sacrificial template to remove them, resulting in conductive double-shell hollow microsphere powder. By sulfonating graphene, a three-dimensional conductive network is constructed from the conductive core-shell microspheres and the metal framework to increase conductivity and promote rapid lithium-ion transport. Furthermore, the hollow structure of the conductive core-shell microspheres and the gaps between the metal framework shells can buffer volume expansion during charging and discharging.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a graphene carbon anode material includes the following steps:

[0008] Step 1: The sulfonic acid groups of 2-acrylamido-2-methylpropanesulfonic acid are grafted onto the surface of polystyrene nanospheres with a particle size of 20-30 nm through free radical polymerization under the action of an initiator, and bonded to aniline monomers through ionic bonds to obtain conductive core-shell microspheres. The conductive core-shell microspheres, cerium nitrate and deionized water are added to a reaction vessel and stirred for 12-14 h at 120-130℃ and 400-500 r / min. After filtration, the filter cake is washed with N,N-dimethylformamide to remove the polystyrene template, and then washed 2-3 times with anhydrous ethanol. It is then vacuum dried at 60-80℃ for 1-2 h to obtain conductive double-shell hollow microsphere powder.

[0009] Step 2: Add sulfonated graphene, conductive double-shell hollow microsphere powder, silicon powder and deionized water to a reaction vessel, ultrasonically disperse for 40-60 min, stir for 1-2 h at 20-25℃ and 400-500 r / min to obtain a mixed suspension, place the mixed suspension in a freeze dryer and freeze dry for 12-14 h, disperse the product in anhydrous ethanol, heat to 170-180℃ and continue the reaction for 12-14 h to obtain a graphene carbon anode material.

[0010] Furthermore, in step one, the ratio of conductive core-shell microspheres, cerium nitrate, and deionized water is 50-60g: 30-40g: 800-900mL.

[0011] Furthermore, in step two, the ratio of sulfonated graphene, conductive double-shell hollow microsphere powder, silicon powder, deionized water, and anhydrous ethanol is 50-60g: 40-50g: 80-90g: 800-900mL: 400-500mL.

[0012] Furthermore, the specific steps for the conductive core-shell microspheres in step one are as follows:

[0013] The precursor solution, aniline, 2,5-dihydroxyterephthalic acid, and 10-12% ethanol solution were added to a reaction vessel and stirred at 80-90℃ and 400-500 r / min for 30-40 min. Then ammonium persulfate was added, the temperature was lowered to 0-4℃, and the reaction was continued for 12-14 h. The mixture was filtered, and the filter cake was washed 2-3 times with deionized water and anhydrous ethanol, respectively. The mixture was then vacuum dried at 60-80℃ for 1-2 h to obtain conductive core-shell microspheres.

[0014] Furthermore, the ratio of the amount of precursor solution, aniline, 2,5-dihydroxyterephthalic acid, ethanol solution and ammonium persulfate is 120-140 mL: 80-90 mL: 70-80 g: 800-900 mL: 5-6 g.

[0015] Furthermore, in step two, the sulfonated graphene powder is processed through the following steps:

[0016] Acyl-chlorographene powder, sodium sulfite, and N,N-dimethylacetamide were added to a reaction vessel and ultrasonically dispersed for 40-60 min. The mixture was then stirred for 24-26 h at 150-160 °C and 400-500 r / min. After naturally cooling to room temperature, deionized water was added, and stirring was continued for 2-3 h. The mixture was then filtered, and the filter cake was washed 2-3 times with deionized water and anhydrous ethanol, respectively. Finally, it was vacuum dried at 60-80 °C for 1-2 h to obtain sulfonated graphene powder.

[0017] Furthermore, the ratio of acyl-chlorographene powder, sodium sulfite, N,N-dimethylacetamide, and deionized water is 50-60g: 56-58g: 300-400mL: 700-800mL.

[0018] Furthermore, the acyl chloride graphene powder is produced through the following steps:

[0019] Graphene oxide powder and a 20-30% thionyl chloride solution were added to a reaction vessel at a ratio of 60-70g:400-600mL. The mixture was stirred for 3-4 hours under a vacuum of -0.1 to -0.03MPa, at a temperature of 80-85℃ and a speed of 400-500r / min. Unreacted thionyl chloride was removed by rotary evaporation, and the mixture was then vacuum dried at 60-80℃ for 1-2 hours to obtain acyl-chlorographene powder.

[0020] Furthermore, the graphene oxide powder is processed through the following steps:

[0021] Flake graphite, phosphorus pentoxide, potassium persulfate, and 98% concentrated sulfuric acid solution were added to a reaction vessel and stirred at 80-85℃ and 400-500 r / min for 3-4 hours. After filtration, the filter cake was washed 2-3 times with deionized water and anhydrous ethanol, respectively, and then vacuum dried at 60-80℃ for 1-2 hours to obtain pre-oxidized graphite. Pre-oxidized graphite, potassium permanganate, 98% concentrated sulfuric acid solution, and 30-40% hydrogen peroxide solution were added to a reaction vessel and stirred at 80-85℃ and 400-500 r / min for 3-4 hours. After filtration, the filter cake was washed 2-3 times with deionized water and anhydrous ethanol, respectively, and then vacuum dried at 60-80℃ for 1-2 hours to obtain graphene oxide powder with a particle size of 30-40 μm.

[0022] Furthermore, the ratio of flake graphite, phosphorus pentoxide, potassium persulfate, and concentrated sulfuric acid solution is 80-90g: 40-50g: 40-50g: 800-900mL.

[0023] Furthermore, the ratio of pre-oxidized graphite, potassium permanganate, concentrated sulfuric acid solution, and hydrogen peroxide solution is 70-80g: 30-40g: 800-900mL: 200-300mL.

[0024] Furthermore, the precursor solution is prepared through the following steps:

[0025] Polystyrene nanospheres with a particle size of 20-30 nm, 2-acrylamide-2-methylpropanesulfonic acid, and deionized water were added to a reaction vessel and stirred for 20-30 min at 20-25 °C and 400-500 r / min. Then, ammonium persulfate was added as an initiator, and the mixture was heated to 60-70 °C and stirred for 4-5 h. The mixture was then allowed to cool naturally to room temperature to obtain the precursor solution.

[0026] Furthermore, the ratio of polystyrene nanospheres, 2-acrylamide-2-methylpropanesulfonic acid, deionized water, and ammonium persulfate is 80-90g: 50-60g: 700-800mL: 1.5-2g.

[0027] The present invention also provides an application of graphene carbon anode material in lithium-ion battery anode materials.

[0028] The beneficial effects of this invention are:

[0029] 1. The graphene carbon anode material prepared by this invention can significantly increase the conductivity of lithium batteries, promote rapid lithium-ion transport, alleviate volume expansion during lithium battery charging and discharging, and increase the cycle capacity, first discharge capacity, and first coulombic efficiency of lithium batteries.

[0030] 2. The conductive double-shell hollow microsphere powder of the present invention is formed by the coordination reaction of cerium nitrate metal ions with 2,5-dihydroxyterephthalic acid grafted on the surface of conductive core-shell microspheres to generate a metal framework. Furthermore, polystyrene nanospheres are a non-polar polymer with high solubility in DMF, which can be used as a sacrificial template for removal, resulting in the conductive double-shell hollow microsphere powder. By sulfonating graphene, a three-dimensional conductive network is constructed with the conductive core-shell microspheres and the metal framework to increase conductivity and promote rapid lithium-ion transport. The hollow structure of the conductive core-shell microspheres and the gaps between the metal framework shells can buffer the volume expansion during charging and discharging. Moreover, the cerium metal ions in the metal framework possess excellent anti-corrosion properties, preventing the electrode material from being corroded by components in the electrolyte and ensuring the service life of the negative electrode material.

[0031] 3. The conductive core-shell microspheres of the present invention are formed by grafting sulfonic acid groups of 2-acrylamide-2-methylpropanesulfonic acid onto the surface of polystyrene nanospheres via free radical polymerization under the initiation of ammonium persulfate, thus forming sulfonated polystyrene. The sulfonic acid groups are ionicly bonded to aniline monomers, promoting the directional growth of polyaniline on the surface of sulfonated polystyrene nanospheres. Polyaniline has excellent conductivity, which can increase the conductivity of graphene. It can avoid the destruction of the conjugated structure of graphene caused by the introduction of sulfonic acid groups, the breakage of the original π-π conjugated system, and the decrease in conductivity. The sulfonic acid groups can participate in the formation of SEI film, generating a stable interface layer rich in LiF, reducing electrolyte decomposition and irreversible consumption of active lithium. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1: A method for preparing a graphene carbon anode material, comprising the following steps:

[0034] S1: Add 80g of flake graphite, 40g of phosphorus pentoxide, 40g of potassium persulfate, and 800mL of 98% concentrated sulfuric acid solution to a reaction vessel. Stir at 80℃ and 400r / min for 3h, filter, wash the filter cake twice with deionized water and anhydrous ethanol, and dry under vacuum at 60℃ for 1h to obtain pre-oxidized graphite. Add 70g of pre-oxidized graphite, 30g of potassium permanganate, 800mL of 98% concentrated sulfuric acid solution, and 200mL of 30% hydrogen peroxide solution to a reaction vessel. Stir at 80℃ and 400r / min for 3h, filter, wash the filter cake twice with deionized water and anhydrous ethanol, and dry under vacuum at 60℃ for 1h to obtain graphene oxide powder with a particle size of 30-40μm.

[0035] S2: Add 60g of graphene oxide powder and 400mL of 20% thionyl chloride solution to a reaction vessel. Stir for 3h under vacuum of -0.1MPa, temperature of 80℃ and speed of 400r / min. Remove unreacted thionyl chloride by rotary evaporation. Dry under vacuum at 60℃ for 1h to obtain acyl-chlorographene powder.

[0036] The carboxyl groups on the surface of graphene oxide undergo a nucleophilic substitution reaction with thionyl chloride to generate acyl chloride groups.

[0037] S3: Add 50g of acyl-chlorographene powder, 56g of sodium sulfite and 300mL of N,N-dimethylacetamide to a reaction vessel, sonicate for 40min, stir at 150℃ and 400r / min for 24h, cool naturally to room temperature, then add 700mL of deionized water, continue stirring for 2h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and vacuum dry at 60℃ for 1h to obtain sulfonated graphene powder.

[0038] The sulfite ions in sodium sulfite act as nucleophiles, attacking the acyl chloride groups on acyl chloride graphene oxide to generate sulfonate intermediates, which are then hydrolyzed to yield sulfonic acid groups.

[0039] S4: Add 80g of polystyrene nanospheres with a particle size of 20-30nm, 50g of 2-acrylamide-2-methylpropanesulfonic acid, and 700mL of deionized water to a reaction vessel. Stir for 20min at 20℃ and 400r / min. Then add 1.5g of ammonium persulfate as an initiator, heat to 60℃, continue stirring for 4h, and cool naturally to room temperature to obtain a precursor solution. Add 120mL of the precursor solution, 80mL of aniline, 70g of 2,5-dihydroxyterephthalic acid, and 800mL of 10% ethanol solution to a reaction vessel. Stir for 30min at 80℃ and 400r / min. Then add 5g of ammonium persulfate, cool to 0℃, and continue the reaction for 12h. Filter, wash the filter cake twice with deionized water and anhydrous ethanol, and dry under vacuum at 60℃ for 1h to obtain conductive core-shell microspheres.

[0040] Initiated by ammonium persulfate, the sulfonic acid groups of 2-acrylamide-2-methylpropanesulfonic acid are grafted onto the surface of polystyrene nanospheres via free radical polymerization to form sulfonated polystyrene. The sulfonic acid groups are ionicly bonded to the aniline monomer, promoting the directional growth of polyaniline on the surface of the sulfonated polystyrene nanospheres. Furthermore, the amino groups on the surface of the conductive core-shell microspheres are bonded to the carboxyl groups of 2,5-dihydroxyterephthalic acid, grafting 2,5-dihydroxyterephthalic acid onto the conductive core-shell microspheres.

[0041] S5: Add 50g of conductive core-shell microspheres, 30g of cerium nitrate and 800mL of deionized water to a reaction vessel, stir for 12h at 120℃ and 400r / min, filter, wash the filter cake with N,N-dimethylformamide to remove the polystyrene template, wash twice with anhydrous ethanol, and vacuum dry at 60℃ for 1h to obtain conductive double-shell hollow microsphere powder.

[0042] The metal ions of cerium nitrate undergo a coordination reaction with 2,5-dihydroxyterephthalic acid grafted onto the surface of conductive core-shell microspheres to form a metal framework. Taking advantage of the high solubility of polystyrene nanospheres in DMF, they are used as sacrificial templates to remove the framework, resulting in conductive double-shell hollow microsphere powder.

[0043] Sulfonic acid groups can participate in the formation of SEI film, generating a stable interface layer rich in LiF, reducing electrolyte decomposition and irreversible consumption of active lithium. Sulfonic acid graphene, conductive core-shell microspheres and metal framework construct a three-dimensional conductive network to increase conductivity and promote rapid lithium ion transport. Furthermore, the hollow structure of conductive core-shell microspheres and the gaps between the metal framework shells can buffer the volume expansion during charging and discharging.

[0044] The cerium metal ions in the metal skeleton have excellent anti-corrosion properties, which can prevent the electrode material from being corroded by the components in the electrolyte and ensure the service life of the negative electrode material.

[0045] S6: Add 50g of sulfonated graphene powder, 40g of conductive double-shell hollow microsphere powder, 80g of silicon powder and 800mL of deionized water to a reaction vessel, ultrasonically disperse for 40min, stir for 1h at 20℃ and 400r / min to obtain a mixed suspension, place the mixed suspension in a freeze dryer and freeze dry for 12h, disperse the product in 400mL of anhydrous ethanol, heat to 170℃ and continue the reaction for 12h to obtain a graphene carbon anode material.

[0046] Example 2: A method for preparing a graphene carbon anode material, comprising the following steps:

[0047] S1: 85g of flake graphite, 45g of phosphorus pentoxide, 45g of potassium persulfate, and 850mL of 98% concentrated sulfuric acid solution were added to a reaction vessel and stirred at 82.5℃ and 450r / min for 3.5h. After filtration, the filter cake was washed twice with deionized water and anhydrous ethanol, respectively, and dried under vacuum at 70℃ for 1.5h to obtain pre-oxidized graphite. 75g of pre-oxidized graphite, 35g of potassium permanganate, 850mL of 98% concentrated sulfuric acid solution, and 250mL of 35% hydrogen peroxide solution were added to a reaction vessel and stirred at 82.5℃ and 450r / min for 3.5h. After filtration, the filter cake was washed twice with deionized water and anhydrous ethanol, respectively, and dried under vacuum at 70℃ for 1.5h to obtain graphene oxide powder with a particle size of 30-40μm.

[0048] S2: 65g of graphene oxide powder and 500mL of 25% thionyl chloride solution were added to a reaction vessel and stirred for 3.5h under vacuum of -0.065MPa, temperature of 82.5℃ and speed of 450r / min. Unreacted thionyl chloride was removed by rotary evaporation and the mixture was dried under vacuum at 70℃ for 1.5h to obtain acyl-chlorographene powder.

[0049] S3: Add 55g of acyl-chlorographene powder, 57g of sodium sulfite and 350mL of N,N-dimethylacetamide to a reaction vessel, sonicate for 50min, stir at 155℃ and 450r / min for 25h, cool naturally to room temperature, then add 750mL of deionized water, continue stirring for 2.3h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and vacuum dry at 70℃ for 1.5h to obtain sulfonated graphene powder.

[0050] S4: Add 85g of polystyrene nanospheres with a particle size of 20-30nm, 55g of 2-acrylamide-2-methylpropanesulfonic acid, and 750mL of deionized water to a reaction vessel. Stir for 25min at 22.5℃ and 450r / min. Then add 1.75g ​​of ammonium persulfate as an initiator, heat to 65℃, and continue stirring for 4.5h. Allow to cool naturally to room temperature to obtain a precursor solution. Add 130mL of the precursor solution, 85mL of aniline, 75g of 2,5-dihydroxyterephthalic acid, and 850mL of 11% ethanol solution to a reaction vessel. Stir for 35min at 85℃ and 450r / min. Then add 5.5g of ammonium persulfate, cool to 2℃, and continue reacting for 13h. Filter, wash the filter cake twice with deionized water and anhydrous ethanol, and dry under vacuum at 70℃ for 1.5h to obtain conductive core-shell microspheres.

[0051] S5: Add 55g of conductive core-shell microspheres, 35g of cerium nitrate and 850mL of deionized water to a reaction vessel, stir for 13h at 125℃ and 450r / min, filter, wash the filter cake with N,N-dimethylformamide to remove the polystyrene template, wash twice with anhydrous ethanol, and vacuum dry at 70℃ for 1.2h to obtain conductive double-shell hollow microsphere powder.

[0052] S6: Add 55g of sulfonated graphene powder, 45g of conductive double-shell hollow microsphere powder, 85g of silicon powder and 850mL of deionized water to a reaction vessel, ultrasonically disperse for 50min, and stir for 1.5h at 22.5℃ and 450r / min to obtain a mixed suspension. Place the mixed suspension in a freeze dryer and freeze dry for 13h. Disperse the product in 450mL of anhydrous ethanol, heat to 175℃, and continue the reaction for 13h to obtain a graphene carbon anode material.

[0053] Example 3: A method for preparing a graphene carbon anode material, comprising the following steps:

[0054] S1: Add 90g of flake graphite, 50g of phosphorus pentoxide, 50g of potassium persulfate, and 900mL of 98% concentrated sulfuric acid solution to a reaction vessel. Stir at 85℃ and 500r / min for 4h, filter, wash the filter cake three times with deionized water and anhydrous ethanol respectively, and dry under vacuum at 80℃ for 2h to obtain pre-oxidized graphite. Add 80g of pre-oxidized graphite, 40g of potassium permanganate, 900mL of 98% concentrated sulfuric acid solution, and 300mL of 40% hydrogen peroxide solution to a reaction vessel. Stir at 85℃ and 500r / min for 4h, filter, wash the filter cake three times with deionized water and anhydrous ethanol respectively, and dry under vacuum at 80℃ for 2h to obtain graphene oxide powder with a particle size of 30-40μm.

[0055] S2: 70g of graphene oxide powder and 600mL of 30% thionyl chloride solution were added to a reaction vessel and stirred for 4h under vacuum of -0.1MPa, temperature of 85℃ and speed of 500r / min. Unreacted thionyl chloride was removed by rotary evaporation and the mixture was dried under vacuum at 80℃ for 2h to obtain acyl-chlorographene powder.

[0056] S3: Add 60g of acyl-chlorographene powder, 58g of sodium sulfite and 400mL of N,N-dimethylacetamide to a reaction vessel, sonicate for 60min, stir at 160℃ and 500r / min for 26h, cool naturally to room temperature, then add 800mL of deionized water, continue stirring for 3h, filter, wash the filter cake three times with deionized water and anhydrous ethanol respectively, and vacuum dry at 80℃ for 2h to obtain sulfonated graphene powder.

[0057] S4: Add 90g of polystyrene nanospheres with a particle size of 20-30nm, 60g of 2-acrylamide-2-methylpropanesulfonic acid, and 800mL of deionized water to a reaction vessel. Stir for 30min at 25℃ and 500r / min. Then add 2g of ammonium persulfate as an initiator, heat to 70℃, continue stirring for 5h, and cool naturally to room temperature to obtain a precursor solution. Add 140mL of the precursor solution, 90mL of aniline, 80g of 2,5-dihydroxyterephthalic acid, and 900mL of 12% ethanol solution to a reaction vessel. Stir for 40min at 90℃ and 500r / min. Then add 6g of ammonium persulfate, cool to 4℃, and continue the reaction for 14h. Filter, wash the filter cake three times with deionized water and anhydrous ethanol, and dry under vacuum at 80℃ for 2h to obtain conductive core-shell microspheres.

[0058] S5: Add 60g of conductive core-shell microspheres, 40g of cerium nitrate and 900mL of deionized water to a reaction vessel, stir for 14h at 130℃ and 500r / min, filter, wash the filter cake with N,N-dimethylformamide to remove the polystyrene template, wash three times with anhydrous ethanol, and vacuum dry at 80℃ for 2h to obtain conductive double-shell hollow microsphere powder.

[0059] S6: Add 60g of sulfonated graphene powder, 50g of conductive double-shell hollow microsphere powder, 90g of silicon powder and 900mL of deionized water to a reaction vessel, ultrasonically disperse for 60min, stir for 2h at 25℃ and 500r / min to obtain a mixed suspension, place the mixed suspension in a freeze dryer and freeze dry for 14h, disperse the product in 500mL of anhydrous ethanol, heat to 180℃ and continue the reaction for 14h to obtain a graphene carbon anode material.

[0060] Comparative Example 1: Based on Example 3, the sulfonated graphene powder in step S5 was replaced with the graphene oxide powder in step S1, while the other steps remained unchanged, and a graphene carbon anode material was prepared.

[0061] Comparative Example 2: Based on Example 3, aniline in step S4 was removed so that it could not form polyaniline, while the other steps remained unchanged, and graphene carbon anode material was prepared.

[0062] Comparative Example 3: Based on Example 3, without step S5, the conductive double-shell hollow microsphere powder in step S6 was replaced with the conductive core-shell microspheres in step S4, while the other steps remained unchanged, and graphene carbon anode material was prepared.

[0063] The graphene carbon anode materials obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare lithium battery anodes, which were then used to prepare lithium battery samples for performance testing. Graphene anode material, acetylene black, and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 8:1:1, then coated onto a copper foil surface. After drying, the samples were pressed into anode sheets using a pressing machine. A lithium metal sheet was used as the counter electrode, and a 1 mol / L LiPF6 solution of ethylene carbonate and diethyl carbonate was used as the electrolyte. The samples were assembled into button batteries in a glove box with a Celgard 2500 separator assembly. The charge-discharge performance of the batteries was tested using a battery tester within a voltage range of 0.01-3V. The results are shown in Table 1.

[0064] Table 1 Performance test results of each lithium battery sample

[0065]

[0066]

[0067] As shown in Table 1, the graphene carbon anode materials obtained in Examples 1-3, when used as lithium battery anodes and then as lithium batteries, exhibit significantly better first discharge capacity, first charge specific capacity, first coulombic efficiency, and conductivity than the comparative examples. Furthermore, the percentage of volume change is significantly lower in the latter case. This indicates that the graphene carbon anode material prepared in this invention can significantly increase the conductivity of lithium batteries, promote rapid lithium-ion transport, alleviate volume expansion during charging and discharging, and increase the cycle capacity, first discharge capacity, and first coulombic efficiency of lithium batteries.

[0068] In Comparative Example 1, sulfonated graphene powder was replaced with graphene oxide powder. The surface of the sulfonated graphene powder is rich in sulfonic acid groups, which can participate in the formation of the SEI film, generating a stable interface layer rich in LiF, reducing electrolyte decomposition and irreversible consumption of active lithium. The cerium metal ions in the metal framework have excellent anti-corrosion properties, which can prevent the electrode material from being corroded by components in the electrolyte and ensure the service life of the negative electrode material.

[0069] In Comparative Example 2, aniline was removed to prevent the formation of polyaniline. The sulfonic acid groups contained in the polyaniline structure can work synergistically with sulfonated graphene powder to stabilize the SEI film, reduce electrolyte decomposition and active lithium consumption, and polyaniline has excellent conductivity, which can form a three-dimensional conductive network with sulfonated graphene and metal framework to promote rapid lithium ion transport.

[0070] In Comparative Example 3, conductive double-shell hollow microsphere powder was replaced with conductive core-shell microspheres. Sulfonated graphene, conductive core-shell microspheres, and a metal framework were used to construct a three-dimensional conductive network to increase conductivity and promote rapid lithium-ion transport. Furthermore, the hollow structure of the conductive core-shell microspheres and the gaps between the metal framework shells can buffer the volume expansion during charging and discharging. In addition, the cerium metal ions in the metal framework have excellent anti-corrosion properties, which can prevent the electrode material from being corroded by the components in the electrolyte and ensure the service life of the negative electrode material.

[0071] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a graphene-carbon anode material, characterized in that, Includes the following steps, Step 1: Under the action of an initiator, the sulfonic acid groups of 2-acrylamido-2-methylpropanesulfonic acid are grafted onto the surface of polystyrene nanospheres with a particle size of 20-30 nm through free radical polymerization, and bonded to aniline monomers through ionic bonds to obtain conductive core-shell microspheres; the conductive core-shell microspheres, cerium nitrate and deionized water are added to a reaction vessel, stirred at 120-130℃ and 400-500 r / min for 12-14 h, filtered, and the filter cake is washed with N,N-dimethylformamide to remove the polystyrene template, then washed with anhydrous ethanol 2-3 times, and vacuum dried to obtain conductive double-shell hollow microsphere powder; Step 2: Add sulfonated graphene, conductive double-shell hollow microsphere powder, silicon powder and deionized water to a reaction vessel, ultrasonically disperse for 40-60 min, stir at 20-25℃ and 400-500 r / min for 1-2 h to obtain a mixed suspension, place the mixed suspension in a freeze dryer and freeze dry for 12-14 h, disperse the product in anhydrous ethanol, heat to 170-180℃ and continue the reaction for 12-14 h to obtain a graphene carbon anode material.

2. The method for preparing a graphene carbon anode material according to claim 1, characterized in that, In step one, the ratio of conductive core-shell microspheres, cerium nitrate, and deionized water is 50-60g: 30-40g: 800-900mL.

3. The method for preparing a graphene carbon anode material according to claim 1, characterized in that, In step two, the ratio of sulfonated graphene, conductive double-shell hollow microsphere powder, silicon powder, deionized water and anhydrous ethanol is 50-60g: 40-50g: 80-90g: 800-900mL: 400-500mL.

4. The method for preparing a graphene carbon anode material according to claim 1, characterized in that, The specific steps for the conductive core-shell microspheres described in step one are as follows: The precursor solution, aniline, 2,5-dihydroxyterephthalic acid and 10-12% ethanol solution were added to the reaction vessel and stirred at 80-90℃ and 400-500r / min for 30-40min. Then ammonium persulfate was added, the temperature was lowered to 0-4℃, and the reaction was continued for 12-14h. The mixture was filtered, washed, and vacuum dried to obtain conductive core-shell microspheres. The ratio of the precursor solution, aniline, 2,5-dihydroxyterephthalic acid, ethanol solution and ammonium persulfate is 120-140 mL: 80-90 mL: 70-80 g: 800-900 mL: 5-6 g.

5. The method for preparing a graphene carbon anode material according to claim 1, characterized in that, The sulfonated graphene powder mentioned in step two is produced through the following steps: Acyl-chlorographene powder, sodium sulfite, and N,N-dimethylacetamide were added to a reaction vessel and ultrasonically dispersed for 40-60 min. The mixture was stirred at 150-160℃ and 400-500 r / min for 24-26 h, and allowed to cool naturally. Then, 700-800 mL of deionized water was added, and stirring was continued for 2-3 h. The mixture was then filtered, washed, and vacuum dried to obtain sulfonated graphene powder. The ratio of the amount of acyl-chlorographene powder, sodium sulfite, N,N-dimethylacetamide and deionized water is 50-60g: 56-58g: 300-400mL: 700-800mL.

6. The method for preparing a graphene carbon anode material according to claim 5, characterized in that, The acyl-chlorographene powder is produced through the following steps: Graphene oxide powder and 20-30 wt% thionyl chloride solution were added to a reaction vessel at a ratio of 60-70 g: 400-600 mL. The mixture was stirred for 3-4 h under vacuum conditions of -0.1 to -0.03 MPa, temperature of 80-85 °C, and speed of 400-500 r / min. Unreacted thionyl chloride was removed by rotary evaporation, and the mixture was then dried under vacuum to obtain acyl-chlorographene powder.

7. The method for preparing a graphene carbon anode material according to claim 6, characterized in that, The graphene oxide powder is obtained through the following steps: Flake graphite, phosphorus pentoxide, potassium persulfate, and 98% concentrated sulfuric acid solution were added to a reaction vessel and stirred at 80-85℃ and 400-500 r / min for 3-4 h. After filtration, washing, and vacuum drying, pre-oxidized graphite was obtained. Pre-oxidized graphite, potassium permanganate, 98 wt% concentrated sulfuric acid solution, and 30-40 wt% hydrogen peroxide solution were added to a reaction vessel and stirred at 80-85℃ and 400-500 r / min for 3-4 h. After filtration, washing, and vacuum drying, graphene oxide powder with a particle size of 30-40 μm was obtained. The ratio of flake graphite, phosphorus pentoxide, potassium persulfate, and concentrated sulfuric acid solution is 80-90g: 40-50g: 40-50g: 800-900mL; the ratio of pre-oxidized graphite, potassium permanganate, concentrated sulfuric acid solution, and hydrogen peroxide solution is 70-80g: 30-40g: 800-900mL: 200-300mL.

8. The method for preparing a graphene carbon anode material according to claim 4, characterized in that, The precursor solution is prepared through the following steps: Polystyrene nanospheres with a particle size of 20-30 nm, 2-acrylamide-2-methylpropanesulfonic acid and deionized water were added to a reaction vessel and stirred at 20-25 °C and 400-500 r / min for 20-30 min. Then ammonium persulfate was added, and the mixture was heated to 60-70 °C and stirred for 4-5 h. The mixture was then allowed to cool naturally to room temperature to obtain the precursor solution. The ratio of polystyrene nanospheres, 2-acrylamide-2-methylpropanesulfonic acid, deionized water and ammonium persulfate is 80-90g: 50-60g: 700-800mL: 1.5-2g.

9. A graphene-carbon anode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the graphene carbon anode material according to claim 9 in lithium-ion battery anode materials.

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