CN106374107B - A kind of preparation method of graphene/metal carbides porous microsphere electrode - Google Patents

Abstract

A method for preparing a graphene/metal carbide porous microsphere electrode relates to a method for preparing a three-dimensional composite material with a hierarchical structure. The purpose of the invention is to solve the problem that the volume expansion of the existing negative electrode material leads to attenuation of battery performance and affects cycle stability. Methods: 1. preparing graphene oxide; 2. preparing a mixed solution; 3. drying; 4. annealing to obtain a graphene/metal carbide porous microsphere electrode. The graphene/metal carbide porous microsphere electrode prepared by the present invention shows good electrochemical lithium storage performance as the lithium ion battery negative electrode material, and the battery prepared with it as the battery negative electrode material has a capacity greater than 0.1A/g under the current density 500mAh/g, the capacity is greater than 300mAh/g at a current density of 3A/g, and the capacity has almost no decay after 500 cycles. The invention is suitable for preparing graphene/metal carbide porous microsphere electrodes.

Description

A kind of preparation method of graphene/metal carbide porous microsphere electrode

technical field

The invention relates to a method for preparing a three-dimensional composite material with a hierarchical structure.

Background technique

With the rapid economic development, human beings are facing the threat of energy depletion in the future. At the same time, the problem of environmental pollution is prominent. It is imminent to develop new clean and green new energy sources. Various energy storage batteries have begun to receive great attention. The performance of the electrode material of the battery is a key factor in determining the performance of the chemical power source. Lithium-ion batteries have excellent properties such as high specific energy, small memory effect, and less environmental pollution. They have become widely used secondary batteries in electronic products such as mobile phones and notebook computers. It also has great application prospects. The negative electrode material is an important part of lithium-ion batteries. The electrode materials are mainly carbon materials, but their capacity is low. The theoretical capacity of graphite is 372mAh/g, which greatly limits the performance of lithium-ion batteries and cannot meet people's needs for high-capacity batteries. need. Current research considers metal materials with higher capacity or improving the theoretical specific capacity of negative electrode materials through composite methods. Regardless of the method, the lithium intercalation and delithiation reactions during the battery cycle will lead to large or small volume expansion of the negative electrode material, thereby destroying the original shape of the negative electrode material, resulting in attenuation of battery performance and affecting cycle stability. sex. In order to solve this problem, the current research mainly considers the three-dimensional hierarchical porous structure to buffer the volume expansion of electrode materials.

The use of metal carbides with high theoretical specific capacity and graphene composite can greatly increase the theoretical specific capacity of the battery. There have been many researches on the preparation of graphene composite materials at home and abroad, but a uniform three-dimensional structure is difficult to obtain. The microsphere electrode material with a porous structure is prepared by combining graphene and metal carbide, which can increase the contact area between the active material and the electrolyte, increase the porosity, reduce the impact of volume expansion, and improve the cycle stability of the battery. performance, thereby improving the performance of lithium-ion batteries.

Contents of the invention

The purpose of the present invention is to solve the problem that the volume expansion of the existing negative electrode material causes battery performance attenuation and affects cycle stability, and provides a preparation method of a graphene/metal carbide porous microsphere electrode.

A kind of preparation method of graphene/metal carbide porous microsphere electrode is specifically finished according to the following steps:

1. Preparation of graphene oxide:

①. Add natural graphite and potassium permanganate to sulfuric acid with a mass fraction of 98%, then stir for 1h to 2h in an ice bath and at a stirring speed of 300r/min to 400r/min to obtain mixture A;

The mass ratio of natural graphite and potassium permanganate described in step 1. 1. is 1:5;

The volume ratio of the mass of the natural graphite described in step 1. to 98% sulfuric acid is 1g: 60mL～100mL;

②. Heat mixture A to 35°C, then keep it warm at 35°C for 1 hour, then add deionized water to mixture A, then raise the temperature of the mixture with deionized water to 90°C~95°C, and then heat the mixture at 35°C Insulate at 90°C to 95°C for 30min to 35min to obtain mixture B;

The volume ratio of mixture A and deionized water described in step 1.2 is 1:1;

③. Naturally cool the mixture B to room temperature, then add the H2O2 solution with a mass fraction of 35% into the mixture B, and react at room temperature for ₁₀ minutes at a stirring speed of 100r/min～300r/min to obtain graphene _oxide aqueous solution; the graphene oxide aqueous solution is centrifuged at a centrifugal speed of 3000r/min to 3500r/min, and the supernatant after centrifugation is taken; Carry out centrifugation again at a centrifugal speed, take the precipitated substance after centrifugation, and then dry it at a temperature of 60°C to 80°C for 1h to 3h to obtain graphene oxide;

The mass fraction of the natural graphite described in step one ① and the mass fraction described in step one ③ are 35% H ₂ O ₂ The volume ratio of the solution is 1g:(5mL～6mL);

2. Prepare the mixed solution:

1. Dissolving the graphene oxide obtained in step 1.3 into water to obtain a graphene oxide solution;

Step 2. The concentration of the graphene oxide solution described in 1. is 5g/L～15g/L;

②. Dissolving polystyrene microspheres in water to obtain a polystyrene microsphere solution with a mass fraction of 8% to 15%;

③. Add metal chloride to the graphene oxide solution, then stir and react at a stirring speed of 500r/min-1000r/min for 1h-2h, and then perform ultrasonic dispersion for 1h-2h to obtain a dark mixed solution;

The volume ratio of the quality of the metal chloride described in step 23. to the graphene oxide solution is (0.4g～1g): 30mL;

④. Add polystyrene microsphere solution with a mass fraction of 8% to 15% to the dark mixed solution, then stir and react at a stirring speed of 500r/min to 1000r/min for 1h to 2h, and then carry out ultrasonic dispersion for 1h to 2h, obtain mixed solution;

The volume ratio of the polystyrene microsphere solution of 8% to 15% and the dark mixed solution in the mass fraction described in step 2.4 is 50:(20 to 40);

3. Drying:

Spray-dry the mixed solution obtained in step 2 ④ under stirring at a temperature of 130°C to 180°C to obtain light yellow fluffy powder;

Four, annealing treatment:

Put the light yellow fluffy powder obtained in step 3 into a tube furnace, and then raise the temperature of the tube furnace from room temperature to 180 °C to 240 °C at a rate of 3 °C/min to 5 °C/min under the protection of an inert gas. Keep warm for 50min~80min, then raise the temperature from 180℃~240℃ to 750℃~850℃ at a rate of 3℃/min~5℃/min, keep warm for 120min~150min, and finally increase the temperature at a rate of 5℃/min~8℃/min The cooling rate was reduced from 750°C to 850°C to 180°C to 240°C, the program was stopped, the temperature was naturally lowered to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode.

Compared with the prior art, the present invention has the following advantages:

One, the preparation method of a kind of metal chloride porous microsphere electrode provided by the present invention not only makes graphene and metal carbide carry out good compounding, obtains the porous three-dimensional electrode material with hierarchical structure;

2. The composition of the graphene/metal carbide porous microsphere electrode prepared by the present invention is carbon and metal chloride, and the main component is carbon. After annealing treatment, the three-dimensional porous structure is firm, and it is not easy to be damaged in the process of lithium intercalation and delithiation. Destruction; the product contains a certain amount of metal carbides, which greatly improves the theoretical specific capacity of the composite material;

3. The present invention builds a nanoscale three-dimensional structure on a micron-scale porous structure, which has a larger specific surface area and porosity, can effectively increase the contact area between the active material and the electrolyte, and greatly increases the lithium ion transport channel and volume expansion buffer space. Effectively reduce the impact of volume expansion, which is more conducive to the lithium intercalation and delithiation reactions in the battery, and greatly improves the performance of the battery;

4. The preparation process of the present invention is simple, the preparation conditions are mild, the price is low, and it can be produced on a large scale; most metal chlorides can be compounded with graphene by this method. When selecting metal-containing compounds, the requirements are relatively low, and they are not limited to metal The use of chloride and metal sulfide can also be used to prepare graphene and metal carbide composite three-dimensional electrode materials with hierarchical structure;

5. The graphene/metal carbide porous microsphere electrode prepared by the present invention exhibits good electrochemical lithium storage performance as a lithium ion battery negative electrode material, and the graphene/metal carbide porous microsphere electrode prepared by the present invention is used as a lithium ion battery. The button battery of battery negative electrode material has a capacity greater than 500mA h/g at a current density of 0.1A/g, and a capacity greater than 300mA h/g at a current density of 3A/g. After 500 cycles, the capacity has almost no attenuation, showing good cycle stability.

The invention is suitable for preparing graphene/metal carbide porous microsphere electrodes.

Description of drawings

Fig. 1 is the 5000 times enlarged SEM figure of the graphene/metal carbide porous microsphere electrode prepared by embodiment one;

Fig. 2 is the 20000 times enlarged SEM figure of the graphene/metal carbide porous microsphere electrode prepared by embodiment one;

Fig. 3 is XRD spectrogram, among Fig. 3, 1 is the XRD curve of the graphene/metal carbide porous microsphere electrode that embodiment one prepares, and 2 is the XRD standard curve of iron carbide;

Fig. 4 is the SEM picture that the graphene/metal carbide porous microsphere electrode that embodiment two prepares enlarges 4000 times;

Fig. 5 is the SEM picture that the graphene/metal carbide porous microsphere electrode that embodiment two prepares enlarges 15000 times;

Fig. 6 is the graphene/metal carbide porous microsphere electrode prepared by embodiment 1 as the cycle performance figure of the button battery under the charge and discharge density of 0.1A/g as the negative electrode material of lithium ion battery;

Fig. 7 is the coulombic efficiency diagram under the charging and discharging density of 0.1A/g with the graphene/metal carbide porous microsphere electrode prepared in embodiment one as the button battery of lithium ion battery negative electrode material;

Fig. 8 is the graphene/metal carbide porous microsphere electrode prepared in Example 1 as the rate performance diagram of the button battery of lithium-ion battery negative electrode material, "▼" in Fig. 8 is the discharge curve, "●" is the charge curve , A is the charge and discharge current density of 0.1A/g, B is the charge and discharge current density of 0.3A/g, C is the charge and discharge current density of 0.5A/g, D is the charge and discharge current density of 1A/g, E is The charge and discharge current density is 3A/g, and F is the charge and discharge current density is 0.1A/g.

Detailed ways:

The implementation examples of the present invention are described in detail below: the present embodiment implements under the premise of the technical solution of the present invention, and provides detailed implementation and specific operation process, but the protection scope of the present invention is not limited to the following implementation example.

Specific embodiment one: this embodiment is a kind of preparation method of graphene/metal carbide porous microsphere electrode, is to finish according to the following steps:

1. Preparation of graphene oxide:

①. Add natural graphite and potassium permanganate to sulfuric acid with a mass fraction of 98%, then stir for 1h to 2h in an ice bath and at a stirring speed of 300r/min to 400r/min to obtain mixture A;

The mass ratio of natural graphite and potassium permanganate described in step 1. 1. is 1:5;

The volume ratio of the mass of the natural graphite described in step 1. to 98% sulfuric acid is 1g: 60mL～100mL;

②. Heat mixture A to 35°C, then keep it warm at 35°C for 1 hour, then add deionized water to mixture A, then raise the temperature of the mixture with deionized water to 90°C~95°C, and then heat the mixture at 35°C Insulate at 90°C to 95°C for 30min to 35min to obtain mixture B;

The volume ratio of mixture A and deionized water described in step 1.2 is 1:1;

③. Naturally cool the mixture B to room temperature, then add the H2O2 solution with a mass fraction of 35% into the mixture B, and react at room temperature for ₁₀ minutes at a stirring speed of 100r/min～300r/min to obtain graphene _oxide aqueous solution; the graphene oxide aqueous solution is centrifuged at a centrifugal speed of 3000r/min to 3500r/min, and the supernatant after centrifugation is taken; Carry out centrifugation again at a centrifugal speed, take the precipitated substance after centrifugation, and then dry it at a temperature of 60°C to 80°C for 1h to 3h to obtain graphene oxide;

The mass fraction of the natural graphite described in step one ① and the mass fraction described in step one ③ are 35% H ₂ O ₂ The volume ratio of the solution is 1g:(5mL～6mL);

2. Prepare the mixed solution:

1. Dissolving the graphene oxide obtained in step 1.3 into water to obtain a graphene oxide solution;

Step 2. The concentration of the graphene oxide solution described in 1. is 5g/L～15g/L;

②. Dissolving polystyrene microspheres in water to obtain a polystyrene microsphere solution with a mass fraction of 8% to 15%;

③. Add metal chloride to the graphene oxide solution, then stir and react at a stirring speed of 500r/min-1000r/min for 1h-2h, and then perform ultrasonic dispersion for 1h-2h to obtain a dark mixed solution;

The volume ratio of the quality of the metal chloride described in step 23. to the graphene oxide solution is (0.4g～1g): 30mL;

④. Add polystyrene microsphere solution with a mass fraction of 8% to 15% to the dark mixed solution, then stir and react at a stirring speed of 500r/min to 1000r/min for 1h to 2h, and then carry out ultrasonic dispersion for 1h to 2h, obtain mixed solution;

The volume ratio of the polystyrene microsphere solution of 8% to 15% and the dark mixed solution in the mass fraction described in step 2.4 is 50:(20 to 40);

3. Drying:

Spray-dry the mixed solution obtained in step 2 ④ under stirring at a temperature of 130°C to 180°C to obtain light yellow fluffy powder;

Four, annealing treatment:

Put the light yellow fluffy powder obtained in step 3 into a tube furnace, and then raise the temperature of the tube furnace from room temperature to 180 °C to 240 °C at a rate of 3 °C/min to 5 °C/min under the protection of an inert gas. Keep warm for 50min~80min, then raise the temperature from 180℃~240℃ to 750℃~850℃ at a rate of 3℃/min~5℃/min, keep warm for 120min~150min, and finally increase the temperature at a rate of 5℃/min~8℃/min The cooling rate was reduced from 750°C to 850°C to 180°C to 240°C, the program was stopped, the temperature was naturally lowered to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode.

Compared with the prior art, the present invention has the following advantages:

1. The preparation method of a metal chloride porous microsphere electrode provided in this embodiment not only enables graphene and metal carbide to be well compounded, but also obtains a porous three-dimensional electrode material with a hierarchical structure;

2. The graphene/metal carbide porous microsphere electrode prepared in this embodiment is composed of carbon and metal chloride, and the main component is carbon. After annealing treatment, the three-dimensional porous structure is firm, and it is not easy to insert lithium in the process of lithium insertion and delithiation. Destroyed; the product contains a certain amount of metal carbides, which greatly improves the theoretical specific capacity of the composite material;

3. This embodiment builds a nanoscale three-dimensional structure on a micron-scale porous structure, which has a larger specific surface area and porosity, which can effectively increase the contact area between the active material and the electrolyte, and greatly increase the lithium ion transport channel and volume expansion buffer space , effectively reducing the impact of volume expansion, more conducive to the lithium intercalation and delithiation reactions in the battery, and greatly improving the performance of the battery;

4. The preparation process of this embodiment is simple, the preparation conditions are mild, the price is low, and it can be produced on a large scale; most metal chlorides can be compounded with graphene using this method. When selecting metal-containing compounds, the requirements are relatively low, and are not limited to The use of metal chlorides and metal sulfides can also be used to prepare graphene and metal carbide composite three-dimensional electrode materials with a hierarchical structure;

5. The graphene/metal carbide porous microsphere electrode prepared in this embodiment exhibits good electrochemical lithium storage performance as a lithium ion battery negative electrode material, and the graphene/metal carbide porous microsphere electrode prepared in this embodiment is used as The lithium-ion battery anode material button battery has a capacity greater than 500mA h/g at a current density of 0.1A/g, and a capacity greater than 300mA h/g at a current density of 3A/g. After 500 cycles, the capacity has almost no attenuation. exhibited good cycle stability.

This embodiment is suitable for preparing graphene/metal carbide porous microsphere electrodes.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the power of the ultrasonic dispersion described in step 2 ③ is 100W-150W. Others are the same as the first embodiment.

Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the power of the ultrasonic dispersion described in step 2 ④ is 100W-150W. Others are the same as those in Embodiment 1 or 2.

Embodiment 4: The difference between this embodiment and one of Embodiments 1 to 3 is that the metal chloride in step 2 ③ is FeCl ₃ ·6H ₂ O or CoCl ₂ . Others are the same as the specific embodiments 1 to 3.

Embodiment 5: The difference between this embodiment and one of Embodiments 1 to 4 is that the inert gas described in step 4 is argon or nitrogen. Others are the same as the specific embodiments 1 to 4.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that the concentration of the graphene oxide solution described in Step 2 ① is 10 g/L-15 g/L. Others are the same as the specific embodiments 1 to 5.

Embodiment 7: The difference between this embodiment and Embodiment 1 to Embodiment 6 is that in step 2 ②, polystyrene microspheres are dissolved in water to obtain polystyrene microspheres with a mass fraction of 10% to 15%. solution. Others are the same as the specific embodiments 1 to 6.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is that in step 3, the mixed solution obtained in step 2 ④ is spray-dried under stirring and at a temperature of 130°C to 160°C to obtain shallow Yellow fluffy powder. Others are the same as those in Embodiments 1 to 7.

Embodiment 9: The difference between this embodiment and one of Embodiments 1 to 8 is that in step 4, the light yellow fluffy powder obtained in step 3 is put into a tube furnace, and then the tube furnace is heated under the protection of an inert gas. Rise from room temperature to 200°C at a heating rate of 3°C/min, hold for 60 minutes, then rise from 200°C to 800°C at a heating rate of 3°C/min, hold for 120 minutes, and finally cool down from 800°C at a cooling rate of 5°C/min The temperature dropped to 200°C, the program was stopped, the temperature was naturally lowered to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode. Others are the same as the specific embodiments 1 to 8.

Embodiment 10: The difference between this embodiment and one of Embodiments 1 to 9 is that in step 4, the light yellow fluffy powder obtained in step 3 is put into a tube furnace, and then the tube furnace is heated under the protection of an inert gas. Rise from room temperature to 180°C to 200°C at a heating rate of 3°C/min to 4°C/min, keep warm for 60min to 80min, and then rise from 180°C to 200°C at a heating rate of 3°C/min to 4°C/min to 750°C-800°C, keep warm for 120min-150min, and finally drop the temperature from 750°C-800°C to 180°C-200°C at a rate of 5°C/min-6°C/min, stop the program, cool down to room temperature naturally, and anneal At the end, the graphene/metal carbide porous microsphere electrode is obtained. Others are the same as the specific embodiments 1 to 9.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one: a kind of preparation method of graphene/metal carbide porous microsphere electrode is prepared according to the following steps:

1. Preparation of graphene oxide:

1. Add natural graphite and potassium permanganate to sulfuric acid with a mass fraction of 98%, then stir for 1.5h in an ice bath and at a stirring speed of 300r/min to obtain a mixture A;

The mass ratio of natural graphite and potassium permanganate described in step 1. 1. is 1:5;

The mass of the natural graphite described in step 1. and the mass fraction are that the volume ratio of 98% sulfuric acid is 1g: 40mL;

②. Heat mixture A to 35°C, then keep it warm at 35°C for 1 hour, then add deionized water to mixture A, then raise the temperature of the mixture with deionized water to 95°C, and then heat the mixture at 95°C Insulated for 30min to obtain mixture B;

The volume ratio of mixture A and deionized water described in step 1.2 is 1:1;

③. Cool the mixture B to room temperature naturally, then add the H2O2 solution with a mass fraction of 35 _% into the mixture B, and react at room temperature for 10min at a stirring speed of 200r/min to obtain an aqueous solution of graphene _oxide ; The graphene aqueous solution is centrifuged at a centrifugal speed of 3000r/min, and the supernatant after centrifugation is taken; the supernatant obtained after centrifugation is again centrifuged at a centrifugal speed of 8000r/min, and the centrifuged supernatant is taken again. The precipitated substance was dried at a temperature of 70° C. for 3 hours to obtain graphene oxide;

The quality of the natural graphite described in step one 1. and the mass fraction described in step one 3. are 35% H ₂ O ₂ The volume ratio of the solution is 1g:5mL;

2. Prepare the mixed solution:

1. Dissolving the graphene oxide obtained in step 1.3 into water to obtain a graphene oxide solution;

The concentration of the graphene oxide solution described in step 2. 1. is 10g/L;

2. Dissolving polystyrene microspheres in water to obtain a polystyrene microsphere solution with a mass fraction of 10%;

③. Add metal chloride to the graphene oxide solution, then stir and react at a stirring speed of 500r/min for 1h, and then perform ultrasonic dispersion for 1h to obtain a dark mixed solution;

The metal chloride described in step 2 ③ is FeCl ₃ ·6H ₂ O;

Step 2. The mass of the metal chloride described in ③ and the volume ratio of the graphene oxide solution are 0.65g: 30mL;

The power of the ultrasonic dispersion described in step 2.3. is 100W;

④. Add polystyrene microsphere solution with a mass fraction of 10% to the dark mixed solution, then stir and react at a stirring speed of 500r/min for 1h, and then carry out ultrasonic dispersion for 1h to obtain a mixed solution;

The volume ratio of the 10% polystyrene microsphere solution and the dark mixed solution in the mass fraction described in step two ④ is 50:30;

The power of the ultrasonic dispersion described in step 2.4 is 100W;

3. Drying:

Spray-dry the mixed solution obtained in step 2(4) under stirring at a temperature of 150°C to obtain light yellow fluffy powder;

Four, annealing treatment:

Put the light yellow fluffy powder obtained in step 3 into a tube furnace, and then raise the temperature of the tube furnace from room temperature to 200 °C at a rate of 3 °C/min under an argon atmosphere, keep it warm for 60 min, and then heat it at a temperature of 3 °C/min. The heating rate of min is raised from 200°C to 800°C, kept for 120min, and finally the cooling rate is 5°C/minn from 800°C to 200°C, the program is stopped, the temperature is naturally cooled to room temperature, and the annealing treatment is completed to obtain graphene/metal carbide porous microsphere electrodes.

Embodiment two: a kind of preparation method of graphene/metal carbide porous microsphere electrode is prepared according to the following steps:

1. Preparation of graphene oxide:

1. Add natural graphite and potassium permanganate to sulfuric acid with a mass fraction of 98%, then stir for 1.5h in an ice bath and at a stirring speed of 300r/min to obtain a mixture A;

The mass ratio of natural graphite and potassium permanganate described in step 1. 1. is 1:5;

The mass of the natural graphite described in step 1. and the mass fraction are that the volume ratio of 98% sulfuric acid is 1g: 40mL;

②. Heat mixture A to 35°C, then keep it warm at 35°C for 1 hour, then add deionized water to mixture A, then raise the temperature of the mixture with deionized water to 95°C, and then heat the mixture at 95°C Insulated for 30min to obtain mixture B;

The volume ratio of mixture A and deionized water described in step 1.2 is 1:1;

③. Cool the mixture B to room temperature naturally, then add the H2O2 solution with a mass fraction of 35 _% into the mixture B, and react at room temperature for 10min at a stirring speed of 200r/min to obtain an aqueous solution of graphene _oxide ; The graphene aqueous solution is centrifuged at a centrifugal speed of 3000r/min, and the supernatant after centrifugation is taken; the supernatant obtained after centrifugation is again centrifuged at a centrifugal speed of 8000r/min, and the centrifuged supernatant is taken again. The precipitated substance was dried at a temperature of 70° C. for 3 hours to obtain graphene oxide;

The quality of the natural graphite described in step one 1. and the mass fraction described in step one 3. are 35% H ₂ O ₂ The volume ratio of the solution is 1g:5mL;

2. Prepare the mixed solution:

1. Dissolving the graphene oxide obtained in step 1.3 into water to obtain a graphene oxide solution;

The concentration of the graphene oxide solution described in step 2. 1. is 10g/L;

2. Dissolving polystyrene microspheres in water to obtain a polystyrene microsphere solution with a mass fraction of 10%;

③. Add metal chloride to the graphene oxide solution, then stir and react at a stirring speed of 500r/min for 1h, and then perform ultrasonic dispersion for 1h to obtain a dark mixed solution;

The metal chloride described in step 2.3. is CoCl ₂ ;

Step 2. The mass of the metal chloride described in ③ and the volume ratio of the graphene oxide solution are 0.65g: 30mL;

The power of the ultrasonic dispersion described in step 2.3. is 120W;

④. Add polystyrene microsphere solution with a mass fraction of 10% to the dark mixed solution, then stir and react at a stirring speed of 500r/min for 1h, and then carry out ultrasonic dispersion for 1h to obtain a mixed solution;

The volume ratio of the 10% polystyrene microsphere solution and the dark mixed solution in the mass fraction described in step two ④ is 50:30;

The power of the ultrasonic dispersion described in step 2.4 is 120W;

3. Drying:

Spray-dry the mixed solution obtained in step 2(4) under stirring at a temperature of 160°C to obtain light yellow fluffy powder;

Four, annealing treatment:

Put the light yellow fluffy powder obtained in step 3 into a tube furnace, and then raise the temperature of the tube furnace from room temperature to 200 °C at a rate of 3 °C/min under an argon atmosphere, keep it warm for 60 min, and then heat it at a temperature of 3 °C/min. The heating rate of min is raised from 200°C to 800°C, kept for 120min, and finally the cooling rate is 5°C/minn from 800°C to 200°C, the program is stopped, the temperature is naturally cooled to room temperature, and the annealing treatment is completed to obtain graphene/metal carbide porous microsphere electrodes.

Assembling the battery: the graphene/metal carbide porous microsphere electrode prepared in Example 1 is made into a slurry and coated on the copper foil, and dried to make an electrode sheet with a diameter of 24 mm; the electrode sheet with a diameter of 24 mm Put it into the negative electrode case of the battery, add 50 μL of electrolyte dropwise to cover the electrode material with the diaphragm, then add 50 μL of electrolyte dropwise, put in the lithium sheet, add the positive electrode case, press the battery tightly, and after standing for 24 hours, the production is completed. The graphene/metal carbide porous microsphere electrode prepared by embodiment one is used as the button cell of lithium-ion battery negative electrode material; Described electrolyte is the LiPF solution that concentration is 1mol/L _; Described diaphragm is polypropylene diaphragm; Described electrolytic solution is the mixed solution of ethylene carbonate, diethyl carbonate and fluoroethylene carbonate, and the volume ratio of ethylene carbonate and diethyl carbonate in the mixed solution is 1:1; Ethylene carbonate and The volume ratio of fluoroethylene carbonate is 1:0.03.

Fig. 1 is the 5000 times enlarged SEM figure of the graphene/metal carbide porous microsphere electrode prepared by embodiment one;

It can be seen from Figure 1 that the graphene/metal carbide porous microsphere electrode prepared in Example 1 has a uniform size distribution, and most of the diameters are concentrated in the range of 1 μm to 2 μm.

Fig. 2 is the 20000 times enlarged SEM figure of the graphene/metal carbide porous microsphere electrode prepared by embodiment one;

It can be seen from Figure 2 that uniform pores of 400nm to 500nm are distributed in the graphene/metal carbide porous microsphere electrode prepared in Example 1, the pore walls are composed of thin-layer graphene, and iron carbide nanoparticles are also distributed in the pore walls.

Fig. 3 is XRD spectrogram, among Fig. 3, 1 is the XRD curve of the graphene/metal carbide porous microsphere electrode that embodiment one prepares, and 2 is the XRD standard curve of iron carbide;

It can be seen from Figure 3 that the graphene/metal carbide porous microsphere electrode prepared in Example 1 is in good agreement with the iron carbide XRD standard curve, which proves that the graphene/metal carbide porous microsphere electrode was successfully synthesized in Example 1.

Fig. 4 is the SEM picture that the graphene/metal carbide porous microsphere electrode that embodiment two prepares enlarges 4000 times;

It can be seen from Fig. 4 that most diameters of the graphene/metal carbide porous microsphere electrode prepared in Example 2 are concentrated in the range of 1 μm to 5 μm in size distribution.

Fig. 5 is the SEM picture that the graphene/metal carbide porous microsphere electrode that embodiment two prepares enlarges 15000 times;

It can be seen from Figure 5 that uniform pores of 300nm to 500nm are distributed in the graphene/metal carbide porous microsphere electrode prepared in Example 2, the pore walls are composed of thin-layer graphene, and cobalt carbide nanoparticles are also distributed in the pore walls.

Fig. 6 is the graphene/metal carbide porous microsphere electrode prepared by embodiment 1 as the cycle performance figure of the button battery under the charge and discharge density of 0.1A/g as the negative electrode material of lithium ion battery;

It can be seen from Figure 6 that the button battery using the graphene/metal carbide porous microsphere electrode prepared in Example 1 as the anode material of the lithium ion battery exhibits good cycle stability, and the capacity hardly decays after 500 cycles.

Fig. 7 is the coulombic efficiency diagram under the charging and discharging density of 0.1A/g with the graphene/metal carbide porous microsphere electrode prepared in embodiment one as the button battery of lithium ion battery negative electrode material;

As can be seen from Figure 7, the button cell with the graphene/metal carbide porous microsphere electrode prepared in Example 1 as the negative electrode material of lithium ion battery shows good cycle stability, and the Coulombic efficiency is almost maintained at Between 99% and 100.

Fig. 8 is the graphene/metal carbide porous microsphere electrode prepared in Example 1 as the rate performance diagram of the button battery of lithium-ion battery negative electrode material, "▼" in Fig. 8 is the discharge curve, "●" is the charge curve , A is the charge and discharge current density of 0.1A/g, B is the charge and discharge current density of 0.3A/g, C is the charge and discharge current density of 0.5A/g, D is the charge and discharge current density of 1A/g, E is The charge and discharge current density is 3A/g, and F is the charge and discharge current density is 0.1A/g.

It can be seen from Figure 8 that the button battery using the graphene/metal carbide porous microsphere electrode prepared in Example 1 as the negative electrode material of lithium-ion battery exhibits good rate stability, and its current density is 3A/g. , its capacity can still be greater than 300mAh/g.

Claims (10)

1. a preparation method of graphene/metal carbide porous microsphere electrode is characterized in that the method is specifically completed in the following steps: 1. Preparation of graphene oxide: ①. Add natural graphite and potassium permanganate to sulfuric acid with a mass fraction of 98%, then stir for 1h to 2h in an ice bath and at a stirring speed of 300r/min to 400r/min to obtain mixture A; The mass ratio of natural graphite and potassium permanganate described in step 1. 1. is 1:5; The volume ratio of the mass of the natural graphite described in step 1. to 98% sulfuric acid is 1g: 60mL～100mL; ②. Heat mixture A to 35°C, then keep it warm at 35°C for 1 hour, then add deionized water to mixture A, then raise the temperature of the mixture with deionized water to 90°C~95°C, and then heat the mixture at 35°C Insulate at 90°C to 95°C for 30min to 35min to obtain mixture B; The volume ratio of mixture A and deionized water described in step 1.2 is 1:1; ③. Naturally cool the mixture B to room temperature, then add the H2O2 solution with a mass fraction of 35% into the mixture B, and react at room temperature for ₁₀ minutes at a stirring speed of 100r/min～300r/min to obtain graphene _oxide aqueous solution; the graphene oxide aqueous solution is centrifuged at a centrifugal speed of 3000r/min to 3500r/min, and the supernatant after centrifugation is taken; Carry out centrifugation again at a centrifugal speed, take the precipitated substance after centrifugation, and then dry it at a temperature of 60°C to 80°C for 1h to 3h to obtain graphene oxide; The mass fraction of the natural graphite described in step one ① and the mass fraction described in step one ③ are 35% H ₂ O ₂ The volume ratio of the solution is 1g:(5mL～6mL); 2. Prepare the mixed solution: 1. Dissolving the graphene oxide obtained in step 1.3 into water to obtain a graphene oxide solution; Step 2. The concentration of the graphene oxide solution described in 1. is 5g/L～15g/L; ②. Dissolving polystyrene microspheres in water to obtain a polystyrene microsphere solution with a mass fraction of 8% to 15%; ③. Add metal chloride to the graphene oxide solution, then stir and react at a stirring speed of 500r/min-1000r/min for 1h-2h, and then perform ultrasonic dispersion for 1h-2h to obtain a dark mixed solution; The volume ratio of the quality of the metal chloride described in step 23. to the graphene oxide solution is (0.4g～1g): 30mL; ④. Add polystyrene microsphere solution with a mass fraction of 8% to 15% to the dark mixed solution, then stir and react at a stirring speed of 500r/min to 1000r/min for 1h to 2h, and then carry out ultrasonic dispersion for 1h to 2h, obtain mixed solution; The volume ratio of the polystyrene microsphere solution of 8% to 15% and the dark mixed solution in the mass fraction described in step 2.4 is 50:(20 to 40); 3. Drying: Spray-dry the mixed solution obtained in step 2 ④ under stirring at a temperature of 130°C to 180°C to obtain light yellow fluffy powder; Four, annealing treatment: Put the light yellow fluffy powder obtained in step 3 into a tube furnace, and then raise the temperature of the tube furnace from room temperature to 180 °C to 240 °C at a rate of 3 °C/min to 5 °C/min under the protection of an inert gas. Keep warm for 50min~80min, then raise the temperature from 180℃~240℃ to 750℃~850℃ at a rate of 3℃/min~5℃/min, keep warm for 120min~150min, and finally increase the temperature at a rate of 5℃/min~8℃/min The cooling rate was reduced from 750°C to 850°C to 180°C to 240°C, the program was stopped, the temperature was naturally lowered to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode. 2. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1, it is characterized in that the power of the ultrasonic dispersion described in step 2.3. is 100W～150W. 3. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1, it is characterized in that the power of the ultrasonic dispersion described in step 2 ④ is 100W～150W. 4. The preparation method of a graphene/metal carbide porous microsphere electrode according to claim 1, characterized in that the metal chloride described in step 2 ③ is FeCl ₃ ·6H ₂ O or CoCl ₂ . 5. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1, is characterized in that the inert gas described in step 4 is argon. 6. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1, it is characterized in that the concentration of the graphene oxide solution described in step 2 1. is 10g/L～15g/L. 7. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1, it is characterized in that step 2 (2) polystyrene microspheres are dissolved in water, and the obtained mass fraction is 10%～15 % polystyrene microsphere solution. 8. The preparation method of a graphene/metal carbide porous microsphere electrode according to claim 1, characterized in that in step 3, the mixed solution obtained in step 2 ④ is stirred and the temperature is 130 ° C to 160 ° C Spray drying was carried out to obtain light yellow fluffy powder. 9. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1 is characterized in that in step 4, the light yellow fluffy powder that step 3 obtains is put into tube furnace, then inert Under the protection of gas, the tube furnace was raised from room temperature to 200°C at a rate of 3°C/min, kept for 60 minutes, then raised from 200°C to 800°C at a rate of 3°C/min, kept for 120 minutes, and finally heated at 5°C The cooling rate per minute was reduced from 800 °C to 200 °C, the program was stopped, the temperature was naturally cooled to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode. 10. the preparation method of a kind of graphene/metal carbide porous microsphere electrode according to claim 1 is characterized in that in step 4, the light yellow fluffy powder that step 3 obtains is put into tube furnace, then inert Under the protection of gas, raise the tube furnace from room temperature to 180°C to 200°C at a rate of 3°C/min to 4°C/min, keep it warm for 60min to 80min, and then increase the temperature at a rate of 3°C/min to 4°C/min Rise from 180°C to 200°C to 750°C to 800°C, keep warm for 120min to 150min, and finally drop the temperature from 750°C to 800°C to 180°C to 200°C at a rate of 5°C/min to 6°C/min, then the program stops. The temperature was naturally lowered to room temperature, and the annealing treatment was completed to obtain a graphene/metal carbide porous microsphere electrode.