Disclosure of Invention
In order to solve the problems of volume change in the process of sodium ion battery antimony-based negative electrode material removal/sodium insertion, easy pulverization of electrode materials after repeated charge and discharge, battery capacity attenuation, poor cycle performance and the like in the prior art, the invention provides the sodium ion battery negative electrode material with reduced graphene oxide loaded with antimony and the preparation method thereof.
The preparation method of the sodium ion battery cathode material with the antimony loaded by the reduced graphene oxide comprises the following specific preparation steps:
the method comprises the following steps: preparing graphene oxide: according to the mass ratio of 4: 3 weighing a certain amount of crystalline flake graphite and NaNO3In a beaker, slowlySlowly adding 200-300 ml of concentrated sulfuric acid (the mass percentage concentration is 98%), and magnetically stirring until the mixture is uniform; slowly adding 30-40 g of potassium permanganate under the magnetic stirring condition, and continuously stirring for 96 hours to obtain a black colloidal substance; sequentially adding 700-800 ml of deionized water and 40-70 ml of hydrogen peroxide (the mass percentage concentration of the hydrogen peroxide is 30%) into the black colloidal substance, and stirring until the mixture is uniform to obtain a yellow solution; centrifuging the obtained yellow solution at a high rotating speed, repeatedly centrifuging at the high rotating speed, and washing with water until the supernatant is neutral; adding the high-speed centrifugation product into deionized water again, stirring uniformly, performing ultrasonic treatment, placing in a centrifuge, centrifuging at a low rotating speed, and collecting the upper-layer gray-brown viscous liquid; repeating the low-speed centrifugation process, pouring the upper-layer gray-brown viscous liquid obtained by multiple times of centrifugation into a dialysis bag, and dialyzing for two weeks to obtain a graphene oxide solution; carrying out rotary evaporation on the graphene oxide solution until the graphene oxide solution is thick, and carrying out freeze drying to obtain graphene oxide; wherein the dosage of the flake graphite is 8-10 g.
Step two: preparing a certain amount of antimony trichloride into an antimony trichloride ethanol solution, and performing ultrasonic treatment for 0.5-1 h to obtain a colorless clear solution; meanwhile, ultrasonically dispersing the graphene oxide prepared in the step one in ethanol for 1-2 hours to obtain a black brown graphene oxide ethanol solution; dropwise adding a small amount of ammonia water (with the mass percentage concentration of 25%) into a graphene oxide ethanol solution (black brown solution), and magnetically stirring for 2-3 h; under the condition of magnetic stirring, slowly dropwise adding the colorless and clear antimony trichloride ethanol solution into a black brown solution containing ammonia water by using an injector, and continuously stirring for 9-12 h to obtain a precursor solution; and drying the precipitate obtained after the centrifugation of the precursor solution at the temperature of between 60 and 80 ℃ to obtain a grey brown precursor solid.
Step three: and (3) placing the gray brown precursor solid in a tubular furnace, heating at the rate of 8-10 ℃/min, performing heat treatment on the gray brown precursor solid for 2-4 hours at the temperature of 550-600 ℃ in a reducing atmosphere with the airflow of 50-80 sccm, and thus obtaining the reduced graphene oxide antimony-loaded sodium-ion battery negative electrode material.
The concentration of the graphene oxide ethanol solution is 1mg/ml, and the volume ratio of the graphene oxide ethanol solution to ammonia water is 200: 1-250: 1; the mass ratio of the graphene oxide to the antimony trichloride is 1: 4-1: 8; the concentration of the antimony trichloride ethanol solution is preferably 0.0006-0.001 mol/L.
In the invention, the high-rotation-speed centrifugation in the step one means that the rotation speed of a centrifuge is 5000-6000 rpm, and the centrifugation time is 5-10 min.
In the invention, the low-rotation-speed centrifugation in the step one means that the rotation speed of the centrifuge is 2000-3000 rpm, and the centrifugation time is 5-10 min.
In the invention, the freeze drying in the step one is carried out at the temperature of minus 50 ℃, the pressure of 20Mpa and the time of 24 hours.
In the invention, the step two of centrifuging the precursor solution means centrifuging the precursor solution under the conditions that the rotating speed of a centrifuge is 8000 rpm-9000 rpm and the centrifuging time is 5-10 min.
In the invention, the slow dropping by using the injector in the step two refers to that: after a colorless clear solution is sucked by a 1mL measuring range injector, the injector is connected with an extension tube, the injector is fixed on a fixed bolt of an injection pump after exhausting and checking that no air bubble exists, the injection pump is started, and the colorless clear solution is dripped at the flow rate of 0.1 mL/min. The above procedure was repeated if the colorless clear solution was used in excess of 1 mL.
In the present invention, the reducing atmosphere in the third step is a mixed atmosphere of hydrogen and argon, preferably a mixed atmosphere of hydrogen and argon at a volume ratio of 5: 95.
The negative electrode material is applied as an electrode of a sodium ion battery, and the result shows that the voltage is 100mA g-1Under the current density, the specific capacity can be kept at 359-502 mAh.g after 10 cycles of circulation-1(ii) a At high current density (2A g)-1) The specific capacity of the Sb-RGO negative electrode material electrode can be stabilized within 147.1-195.6 mAh.g after the circulation is carried out for 100 times-1The method has excellent cycling stability and the coulombic efficiency is more than 97 percent.
The invention has the advantages that:
1. the sodium ion battery cathode material with the antimony loaded by the reduced graphene oxide has excellent cycle rate performance. At 2A g-1After circulating for 100 circles under the high current density, the Sb-rGO can still keep 200mAh g-1And coulombic efficiency was maintained above 97%.
2. The preparation method provided by the invention is used for preparing the sodium ion battery cathode material of the reduced graphene oxide loaded antimony, a surfactant and a reducing agent are not required to be added in the preparation process, the method is simple, the cost is low, and the preparation method is suitable for large-scale preparation.
Detailed Description
The invention provides a sodium ion battery negative electrode material with reduced graphene oxide loaded with antimony and a preparation method thereof, which are described in detail below with reference to the accompanying drawings and examples.
Example 1
The preparation method of the sodium ion battery cathode material with reduced graphene oxide loaded with antimony comprises the following steps:
the method comprises the following steps: and preparing graphene oxide.
Step 101, weighing 10g of flake graphite and 7.5g of NaNO3Slowly adding 300ml of concentrated sulfuric acid (98%) into a beaker, and magnetically stirring until the mixture is uniform; slowly add 40g potassium permanganate with magnetic stirring and continue stirring for 96 hours to obtain a black gum-like material.
102, sequentially adding 800ml of deionized water and 60ml of hydrogen peroxide (30%) into the black colloidal substance, and stirring until the mixture is uniform to obtain a yellow solution; centrifuging the obtained yellow solution at 6000rpm for 5min at high speed to obtain high-speed centrifugation product; further preferably, the high-speed centrifugation process is repeated for 3-5 times, and the high-speed centrifugation product is obtained after the supernatant is washed to be neutral.
Step 103, adding the high-rotation-speed centrifugal product into deionized water again, uniformly stirring, performing ultrasonic treatment for 10min, placing in a centrifuge, performing low-rotation-speed centrifugation, performing centrifugation at 2000rpm for 5min, and collecting the upper-layer gray-brown viscous liquid;
step 104, repeating the step 103 and the low-speed centrifugation process for 3-5 times, pouring the upper-layer viscous liquid collected by multiple times of centrifugation into a dialysis bag, and dialyzing for two weeks to obtain a graphene oxide solution; and (3) carrying out rotary evaporation on the graphene oxide solution until the graphene oxide solution is thick, and carrying out freeze drying to obtain the graphene oxide. The freeze drying is carried out at the temperature of minus 50 ℃, the pressure of 20Mpa and the time of 24 hours. The temperature of the rotary evaporation is lower than 40 ℃.
Step two: weighing 2g of antimony trichloride in a glass bottle, dropwise adding 10ml of ethanol, and carrying out ultrasonic treatment for 0.5h to obtain 10ml of colorless and clear antimony trichloride ethanol solution with the concentration of 0.8M; simultaneously taking 20mg of the graphene oxide prepared in the first step into ethanol, and performing ultrasonic dispersion for 1 hour to obtain 20ml of graphene oxide ethanol solution;
0.1ml of ammonia water (ammonia water solution with the preparation percentage of 25%) is dripped into the graphene oxide ethanol solution, and the mixture is magnetically stirred for 3 hours; under the condition of magnetic stirring, 0.76mL of colorless clear solution is extracted by a 1mL syringe, the syringe is connected with an extension tube, the syringe is fixed on a fixed bolt of an injection pump after exhausting and checking that no air bubble exists, the injection pump is started, the colorless clear solution is dripped at the flow rate of 0.1mL/min, and the stirring is continued for 12 hours, so that a black-gray precursor solution is obtained; centrifuging the dark gray precursor solution at 8000rpm for 5min to obtain precipitate, and drying at 80 deg.C for 12h to obtain dark brown precursor solid powder;
step three: and (3) placing the gray brown precursor solid powder in a tubular furnace, heating at a rate of 10 ℃/min, carrying out heat treatment on the gray brown precursor solid powder for 2 hours at 550 ℃ in a mixed reducing atmosphere consisting of hydrogen and argon in a volume ratio of 5:95, and thus obtaining the sodium-ion battery cathode material with reduced graphene oxide loaded with antimony.
As shown in fig. 1: XRD analysis shows that the product prepared in the third step is the high-crystallinity graphene antimony-loaded sodium ion battery cathode material. Diffraction peaks at 23.6 °, 25.1 °, 28.7 °, 39.8 °, 42 °, 46.8 °, 48.4 °, and 51.6 ° correspond to antimony Sb (003), (101), (012), (104), (015), (006), (202) crystal planes, respectively, and all sharp diffraction peaks can correspond to hexagonal structure antimony of PDF numbers 85-1324. And FIG. 2 is an SEM photograph of the product obtained in the third step, and it can be seen that the reduced graphene oxide is a nearly transparent film, antimony particles are uniformly loaded on the inner surface and the outer surface of the reduced graphene oxide, and the particle size is 80-500 nm. Fig. 3 is a TEM photograph of the negative electrode material prepared in step three, the inset is a sea (electron diffraction) picture, and sea diffraction fringes correspond to the structures of Sb one by one, which proves that Sb particles exist and a large amount of antimony particles are loaded on the surface of a large sheet of reduced graphene oxide.
Preparing a sodium ion battery electrode by applying the reduced graphene oxide antimony-loaded sodium ion battery negative electrode material and testing the performance of the sodium ion battery electrode:
the preparation of the electrode is that the sodium ion battery cathode material of the reduced graphene oxide loaded antimony is used as an active substance, and is mixed with a conductive agent (conductive carbon black) and a binder (sodium carboxymethyl cellulose) according to the weight ratio of 7:2:1 to be used as an electrode material; preparing an electrode material into slurry by taking deionized water as a solvent, and coating the slurry on the rough surface of a clean round copper foil with the diameter of 1.2cm to obtain an electrode slice; and then placing the electrode slice in a vacuum drying oven, and carrying out vacuum drying for 15h at the temperature of 80 ℃ to obtain the sodium-ion battery electrode. The test cell of the invention adopts a CR2032 button cell, takes a sodium metal sheet as a counter electrode, the concentration of the electrolyte is 1M, and the solute is sodium perchlorate (NaClO)4) The solvent is Propylene Carbonate (PC) and Ethylene Carbonate (EC) with the volume ratio of 1: 1. The current density of the multiplying power performance test is 0.2C, 0.4C, 1C, 2C, 5C, 10C and 20C, the current density of the 100-time cyclic charge and discharge test is 4C, wherein 1C is equal to 500mA/g, and the test voltage range is 0.01-0.3V.
FIG. 4 is a graph of specific charge-discharge capacity performance of Sb-rGO negative electrode material electrode under different current densities at 100mAg-1After circulating for 10 circles under the current density, the negative electrode material electrodeThe specific capacity can be stabilized at 416mAh-1Under different current charging and discharging conditions, the coulombic efficiency can still be kept above 97%. FIG. 5 shows Sb-rGO cathode material electrode at 2Ag -1100 cycles of charge-discharge diagram under current density. In 2Ag-1Under the condition of high current density, the specific capacity of the Sb-rGO cathode material electrode prepared by the method can be stabilized at 171mAh-1And the cycle performance is excellent.
Example 2
The preparation method of the reduced graphene oxide loaded antimony negative electrode material comprises the following steps:
the method comprises the following steps: the same as in example 1.
Step two: weighing 2g of antimony trichloride in a glass bottle, dropwise adding 10ml of ethanol, and carrying out ultrasonic treatment for 0.5h to obtain 10ml of colorless and clear antimony trichloride ethanol solution with the concentration of 0.8M; simultaneously measuring 30mg of graphene oxide prepared in the first step, and ultrasonically dispersing the graphene oxide in 40ml of ethanol solution for 1h to obtain a dark brown solution; dropwise adding 0.18ml of ammonia water (25%) into the graphene oxide ethanol solution, and magnetically stirring for 3 hours; under the condition of magnetic stirring, 0.85mL of colorless clear solution is extracted by a 1mL syringe, the syringe is connected with an extension tube, the syringe is fixed on a fixed bolt of an injection pump after exhausting and checking that no air bubble exists, the injection pump is started, the colorless clear solution is dripped at the flow rate of 0.1mL/min, and the stirring is continued for 12 hours, so that a black and gray solution is obtained; centrifuging the dark gray solution at 8500rpm for 8min to obtain precipitate, and drying at 80 deg.C for 10 hr to obtain dark brown powder;
step three: and (3) placing the gray brown powder into a tubular furnace, heating at a speed of 10 ℃/min, carrying out heat treatment on the gray brown powder at a flow rate of 50-80 sccm for 2 hours at 550 ℃ in a mixed reducing atmosphere consisting of hydrogen and argon in a volume ratio of 5:95, and thus obtaining the reduced graphene oxide loaded antimony negative electrode material.
The prepared reduced graphene oxide antimony-loaded sodium ion battery negative electrode material is abbreviated as Sb-rGO negative electrode material, large reduced graphene oxide particles are loaded on the surface of the large reduced graphene oxide, the reduced graphene oxide antimony-loaded negative electrode material prepared in the step three is mixed with a conductive agent (conductive carbon black) and a binder (sodium carboxymethylcellulose) according to the weight ratio of 7:2:1 to be used as an electrode material, and deionized water is used as a solventPreparing the electrode material into slurry, coating the slurry on clean round copper foil with the diameter of 1.2cm to obtain an electrode plate, then placing the electrode plate in a vacuum drying oven, and carrying out vacuum drying for 15h at 80 ℃ to obtain the sodium-ion battery. The test cell of the invention adopts a CR2032 button cell, takes a sodium metal sheet as a counter electrode, the concentration of the electrolyte is 1M, and the solute is sodium perchlorate (NaClO)4) The solvent is Propylene Carbonate (PC) and Ethylene Carbonate (EC) with the volume ratio of 1: 1. The current density of the multiplying power performance test is 0.2C, 0.4C, 1C, 2C, 5C, 10C and 20C, the current density of the 100-time cyclic charge and discharge test is 4C, wherein 1C is equal to 500mA/g, and the test voltage range is 0.01-0.3V.
At 100mAg-1Under the current density, the first discharge specific capacity of the material electrode reaches 810mAh-1And the specific capacity can be kept at 410mAh.g after 10 cycles of circulation-1And excellent sodium storage capacity is shown. Under high current density (2 Ag)-1) The specific capacity of the Sb-RGO negative electrode material electrode can be stabilized at 165.6mAh.g after the circulation for 100 times-1The method has excellent cycling stability and the coulombic efficiency is more than 97 percent.
Example 3:
the method comprises the following steps: preparing graphene oxide:
taking 8g of flake graphite, and mixing the materials in a mass ratio of 4: 3 weighing NaNO3Mixing the two solutions in a beaker, slowly adding 200ml of concentrated sulfuric acid (the mass percent concentration is 98%) into the beaker, and magnetically stirring the mixture until the mixture is uniform;
slowly adding 30g of potassium permanganate under the magnetic stirring condition, and continuously stirring for 96 hours to obtain a black colloidal substance; sequentially adding 800ml of deionized water and 70ml of hydrogen peroxide (the mass percentage concentration of the hydrogen peroxide is 30%) into the black colloidal substance, and stirring the mixture until the mixture is uniform to obtain a yellow solution;
centrifuging the obtained yellow solution at a high rotating speed, and washing with water until the supernatant is neutral; adding the high-speed centrifugation product into deionized water again, stirring uniformly, performing ultrasonic treatment, placing in a centrifuge, centrifuging at a low rotating speed, and collecting the upper-layer gray-brown viscous liquid; repeating the low-speed centrifugation process, pouring the upper-layer gray-brown viscous liquid obtained by multiple times of centrifugation into a dialysis bag, and dialyzing for two weeks to obtain a graphene oxide solution; and (3) carrying out rotary evaporation on the graphene oxide solution until the graphene oxide solution is thick, and carrying out freeze drying to obtain the graphene oxide.
The high-speed centrifugation rotating speed is 5000rpmrpm, and the centrifugation time is 10 min.
The low-speed centrifugation rotating speed is 2000rpm, and the centrifugation time is 5 min.
The freeze drying is carried out at the temperature of minus 50 ℃, the pressure of 20Mpa and the time of 24 hours.
Step two: preparing antimony trichloride into an antimony trichloride ethanol solution, and performing ultrasonic treatment for 0.5h to obtain a colorless clear solution;
meanwhile, ultrasonically dispersing the graphene oxide prepared in the step one in ethanol for 1 hour to obtain a black brown graphene oxide ethanol solution; dropwise adding a small amount of ammonia water (with the mass percentage concentration of 25%) into the graphene oxide ethanol solution (black brown solution), and magnetically stirring for 2 hours; the concentration of the graphene oxide ethanol solution is 1mg/ml, and the volume ratio of the graphene oxide ethanol solution to ammonia water is 200: 1; the mass ratio of the graphene oxide to the antimony trichloride is 1: 4.
Under the condition of magnetic stirring, slowly dropwise adding the colorless and clear antimony trichloride ethanol solution into a black brown solution containing ammonia water by using an injector, and continuously stirring for 9-12 h to obtain a precursor solution; and drying the precipitate obtained after the centrifugation of the precursor solution at the temperature of between 60 and 80 ℃ to obtain a grey brown precursor solid.
Wherein, the precursor solution centrifugation means the centrifugation under the conditions that the rotation speed of a centrifuge is 8000rpm and the centrifugation time is 5 min.
Step three: and (3) placing the gray brown precursor solid in a tubular furnace, heating at the rate of 8 ℃/min, performing heat treatment on the gray brown precursor solid at the temperature of 600 ℃ for 4 hours in a reducing atmosphere to obtain the sodium-ion battery negative electrode material with the reduced graphene oxide loaded with antimony.
The negative electrode material prepared by the steps comprises graphene oxide and antimony particles, wherein the reduced graphene oxide is an approximately transparent film, the antimony particles are uniformly loaded on the inner surface and the outer surface of the reduced graphene oxide, and the particle size is 80-500 nm. The negative electrode material is used as a sodium ion batteryThe electrode, electrode preparation and performance test conditions were the same as in example 1, and the results showed that at 100mAg-1Under the current density, the first discharge specific capacity of the material electrode is 742mAh-1The specific capacity can be kept at 359mAh.g after 10 cycles of circulation-1Under high current density (2 Ag)-1) The specific capacity of the Sb-RGO negative electrode material electrode can be stabilized at 147.1 mAh.g after the circulation for 100 times-1The method has excellent cycling stability and the coulombic efficiency is more than 97 percent.
Example 4:
the method comprises the following steps: preparing graphene oxide:
taking 10g of flake graphite, and mixing the materials in a mass ratio of 4: 3 weighing NaNO3Mixing the two solutions in a beaker, slowly adding 300ml of concentrated sulfuric acid (the mass percent concentration is 98%) into the beaker, and magnetically stirring the mixture until the mixture is uniform;
slowly adding 40g of potassium permanganate under the magnetic stirring condition, and continuously stirring for 96 hours to obtain a black colloidal substance; sequentially adding 700ml of deionized water and 40ml of hydrogen peroxide (the mass percentage concentration of the hydrogen peroxide is 30%) into the black colloidal substance, and stirring the mixture until the mixture is uniform to obtain a yellow solution;
centrifuging the obtained yellow solution at a high rotating speed, repeatedly centrifuging at the high rotating speed, and washing with water until the supernatant is neutral; adding the high-speed centrifugation product into deionized water again, stirring uniformly, performing ultrasonic treatment, placing in a centrifuge, centrifuging at a low rotating speed, and collecting the upper-layer gray-brown viscous liquid; repeating the low-speed centrifugation process, pouring the upper-layer gray-brown viscous liquid obtained by multiple times of centrifugation into a dialysis bag, and dialyzing for two weeks to obtain a graphene oxide solution; and (3) carrying out rotary evaporation on the graphene oxide solution until the graphene oxide solution is thick, and carrying out freeze drying to obtain the graphene oxide.
The high-speed centrifugation rotating speed is 6000rpm, and the centrifugation time is 5 min.
The low-speed centrifugation rotating speed is 3000rpm, and the centrifugation time is 10 min.
The freeze drying is carried out at the temperature of minus 50 ℃, the pressure of 20Mpa and the time of 24 hours.
Step two: preparing a certain amount of antimony trichloride into an antimony trichloride ethanol solution, and performing ultrasonic treatment for 1h to obtain a colorless clear solution;
meanwhile, carrying out ultrasonic dispersion on the graphene oxide prepared in the step one in ethanol for 2 hours to obtain a black brown graphene oxide ethanol solution; dropwise adding a small amount of ammonia water (with the mass percentage concentration of 25%) into the graphene oxide ethanol solution (black brown solution), and magnetically stirring for 3 hours; the concentration of the graphene oxide ethanol solution is 1mg/ml, and the volume ratio of the graphene oxide ethanol solution to ammonia water is 250: 1; the mass ratio of the graphene oxide to the antimony trichloride is 1: 8.
Under the condition of magnetic stirring, slowly dropwise adding the colorless and clear antimony trichloride ethanol solution into a black brown solution containing ammonia water by using an injector, and continuously stirring for 9-12 h to obtain a precursor solution; and drying the precipitate obtained after the centrifugation of the precursor solution at the temperature of between 60 and 80 ℃ to obtain a grey brown precursor solid.
The centrifugation of the precursor solution refers to the centrifugation under the conditions that the rotation speed of a centrifuge is 9000rpm and the centrifugation time is 10 min.
Step three: and (3) placing the gray brown precursor solid in a tubular furnace, heating at a rate of 10 ℃/min, performing heat treatment on the gray brown precursor solid at a temperature of 550 ℃ for 2 hours in a reducing atmosphere to obtain the sodium-ion battery negative electrode material with the reduced graphene oxide loaded with antimony.
The negative electrode material comprises graphene oxide and antimony particles, wherein the reduced graphene oxide is a nearly transparent film, the antimony particles are uniformly loaded on the inner surface and the outer surface of the reduced graphene oxide, and the particle size is 80-500 nm.
The negative electrode material is used as an electrode of a sodium ion battery, the electrode preparation and performance test conditions are the same as those of example 1, and the first discharge capacity of the negative electrode material electrode is up to 773mAh g-1At 100mAg-1Under the current density, the reversible capacity can be stabilized at 502mAh g-1At high current density (2 Ag)-1) The specific capacity of the Sb-RGO negative electrode material electrode can be stabilized at 195.6mAh.g after the circulation for 100 times-1The method has excellent cycling stability and the coulombic efficiency is more than 98 percent.