Disclosure of Invention
The technical problem to be solved is as follows: the invention aims to provide a preparation method of a lithium battery cathode material, and the prepared lithium battery cathode material obviously improves the conductivity of SiO due to the unique structure and the hybrid structure supported by conductive carbon, thereby improving the electrochemical performance.
The technical scheme is as follows: a preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 125-130 ℃, refluxing for 10-20h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 100-300mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 7-8min to obtain gold-doped graphene oxide;
(6) dissolving 1.5-5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3h at the temperature of 700 and 800W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, sequentially washing with distilled water and ethanol for 3-5 times, and oven drying at 60 deg.C;
(10) taking out and putting into a tubular furnace, heating to 700 and 750 ℃ at the speed of 5 ℃/min under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Further, the mass of the silica sol in the step (5) is 4 g.
Further, the ultrasonic power in the step (7) is 850W.
Further, the calcination temperature in the step (10) is 730 ℃.
Has the advantages that:
1. the nitric acid reflux oxidation is adopted, so that not only can the graphene oxide be purified and impurities be removed, but also oxygen-containing functional groups can be introduced to the surface of the graphene oxide, the hydrophilicity of the graphene oxide is improved, and the graphene oxide can have greater application potential.
2. The nitric acid oxidation constructs defect sites, some hydrophilic groups such as oxygen-containing functional groups and the like on the surface of the graphene oxide, and gold ions can form stable coordination compounds with various ligands and exist in an ionic form in a solution, so that the deposition doping of the gold ions on the graphene oxide in the solution is realized.
3. According to the invention, the hybrid of the silica sol, the glycine and the gold-doped graphene oxide is successfully prepared through self-assembly of the silica sol, the glycine and the gold-doped graphene oxide in continuous ultrasonic, hydrothermal and thermal treatment, wherein the gold-doped graphene oxide can effectively improve the cycle performance of the carbon-coated silicon dioxide composite material as a LiBs cathode material, and the structural stability of the carbon-coated silicon dioxide composite material is improved. Meanwhile, the unique structure and the hybrid structure supported by conductive carbon obviously improve the conductivity of SiO, thereby improving the electrochemical performance.
Detailed Description
Example 1
A preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 125 ℃, refluxing for 10h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 100mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 7min to obtain gold-doped graphene oxide;
(6) dissolving 1.5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 700W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, washing with distilled water and ethanol for 3 times, and oven drying at 60 deg.C;
(10) taking out, putting into a tubular furnace, heating to 700 ℃ at a speed of 5 ℃/min under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Example 2
A preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 126 ℃, refluxing for 12h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 150mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 7.5min to obtain gold-doped graphene oxide;
(6) dissolving 2.5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 720W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, washing with distilled water and ethanol for 4 times, and oven drying at 60 deg.C;
(10) taking out, putting into a tubular furnace, heating to 720 ℃ at a speed of 5 ℃/min under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Example 3
A preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 127 ℃, refluxing for 15h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 200mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 7.5min to obtain gold-doped graphene oxide;
(6) dissolving 3.5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 750W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, washing with distilled water and ethanol for 4 times, and oven drying at 60 deg.C;
(10) taking out, putting into a tubular furnace, heating to 730 ℃ at the speed of 5 ℃/min under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Example 4
A preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 128 ℃, refluxing for 18h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 250mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 7.5min to obtain gold-doped graphene oxide;
(6) dissolving 4g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 780W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, washing with distilled water and ethanol for 4 times, and oven drying at 60 deg.C;
(10) taking out and putting into a tubular furnace, heating to 740 ℃ at the speed of 5 ℃/min under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Example 5
A preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 130 ℃, refluxing for 20h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(4) taking 75mg of acid graphene oxide, and adding 300mL of water to obtain an acid graphene oxide dispersion liquid;
(5) dripping into gold sol solution, and vibrating and depositing for 8min to obtain gold-doped graphene oxide;
(6) dissolving 5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(7) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 800W;
(8) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(9) naturally cooling to room temperature, washing with distilled water and ethanol for 5 times, and oven drying at 60 deg.C;
(10) taking out and putting into a tubular furnace, heating to 750 ℃ under the protection of nitrogen, and calcining for 2 h;
(11) and naturally cooling to obtain the lithium battery cathode material.
Comparative example 1
This comparative example differs from example 5 in that the acid oxidation treatment was not performed, as follows:
a preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 15ml of sodium citrate solution into 100ml of chloroauric acid solution, heating and boiling for 30min to obtain gold sol solution;
(2) taking 75mg of graphene oxide, and adding 300mL of water to obtain a graphene oxide dispersion solution;
(3) dripping into gold sol solution, and vibrating and depositing for 8min to obtain gold-doped graphene oxide;
(4) dissolving 5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(5) adding gold-doped graphene oxide, and performing ultrasonic treatment for 3 hours at 800W;
(6) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(7) naturally cooling to room temperature, washing with distilled water and ethanol for 5 times, and oven drying at 60 deg.C;
(8) taking out and putting into a tubular furnace, heating to 750 ℃ under the protection of nitrogen, and calcining for 2 h;
(9) and naturally cooling to obtain the lithium battery cathode material.
Comparative example 2
The difference between the comparative example and the example 5 is that the graphene is not doped with gold, and the specific difference is as follows:
a preparation method of a lithium battery negative electrode material comprises the following steps:
(1) adding 75mg of graphene oxide into 100ml of prepared nitric acid solution with the mass fraction of 40%, and ultrasonically oscillating for 20 min;
(2) heating and boiling to 130 ℃, refluxing for 20h, taking out, washing to be neutral, and filtering to obtain acid graphene oxide;
(3) dissolving 5g of silica sol and 5g of glycine in deionized water to obtain a silicon dioxide/glycine solution;
(4) adding acid graphene oxide, and performing ultrasonic treatment for 3 hours at 800W;
(5) transferring to an autoclave, and keeping the temperature at 190 ℃ for 12 h;
(6) naturally cooling to room temperature, washing with distilled water and ethanol for 5 times, and oven drying at 60 deg.C;
(7) taking out and putting into a tubular furnace, heating to 750 ℃ under the protection of nitrogen, and calcining for 2 h;
(8) and naturally cooling to obtain the lithium battery cathode material.
Assembling the battery:
the lithium battery negative electrode material, the conductive agent carbon black and the adhesive acrylic resin are mixed into slurry according to the mass ratio of 6:2:2, the slurry is coated on a Cu foil, then the Cu foil is dried in vacuum for 2 hours at 150 ℃, a copper foil is punched into an electrode plate with a certain diameter by a punching machine after a solvent is removed, the electrode plate is placed in a tablet machine and is set to be 6MPa, and the electrode plate is pressed for more than 5 seconds. Other gas content requirement H in argon filled glove box2Volume fraction of O less than 5X 10-7. And O2Is less than 5 x 10-7Assembling the battery by using a CR2016 button battery as a test model, wherein the negative electrode material adopts the negative electrode material of the lithium battery, the positive electrode adopts a metal lithium sheet, and the electrolyte is 1mol/L LiPF6And ethylene carbonate/dimethyl carbonate (volume ratio 1:1), and Celgard 2400 polypropylene porous membrane was used as a separator.
And (3) testing the electrochemical performance of the battery:
and at normal temperature, a Land battery test system is adopted to perform constant current charge-discharge cycle performance test and multiple rate cycle performance test at a certain current density within 0.01-3V. The specific capacity was measured at a current density of 186mA · h/g.
TABLE 1
|
Coulomb efficiency/%
|
Specific capacity mA.h/g
|
Example 1
|
99.2
|
901.7
|
Example 2
|
99.4
|
906.4
|
Example 3
|
99.5
|
912.4
|
Example 4
|
99.7
|
921.8
|
Example 5
|
99.5
|
920.1
|
Comparative example 1
|
94.5
|
834.6
|
Comparative example 2
|
95.0
|
801.2 |