CN107017404A - A kind of preparation method of nitrogen-doped carbon supported cobaltosic oxide electrode material - Google Patents

Abstract

A preparation method of a nitrogen-doped carbon-supported cobalt tetroxide electrode material. Firstly, a cobalt source is uniformly mixed with an ionic liquid; Continue to raise the temperature to 600°C-1600°C for 60-360min, cool to room temperature; then raise the temperature to 200°C-700°C in an air atmosphere, keep it for 20-120min, and obtain nitrogen-doped carbon-supported cobalt tetroxide electrode material after cooling. The preparation process of the invention is simple, the tricobalt tetroxide particles are small, the dispersibility is good, and the nitrogen content in the carbon matrix and the loading capacity of the tricobalt tetroxide are adjustable. Since the nitrogen-doped carbon matrix has good conductivity and can effectively prevent the volume effect of cobalt tetroxide particles during charge and discharge, the prepared nitrogen-doped carbon-supported cobalt tetroxide material has high lithium storage capacity when used as a negative electrode material for lithium-ion batteries and good cycle performance.

Description

A preparation method of nitrogen-doped carbon-supported cobalt tetroxide electrode material

technical field

The invention relates to the preparation technology of electrode materials, in particular to the preparation of nitrogen-doped carbon-loaded tricobalt tetroxide electrode materials, and belongs to the technical field of energy materials and new materials.

Background technique

As a new type of anode material for lithium-ion batteries, metal oxide materials have the advantages of high theoretical capacity, abundant reserves, low cost, and high chemical stability, but their poor electrical conductivity leads to low charge and discharge rates for such materials. At the same time, the huge volume expansion and large initial irreversible capacity during the charging and discharging process limit the commercial application of such materials. In recent years, people have attempted to prepare metal oxide nanomaterials with specific morphologies in an attempt to reduce the volume change of the material during charge and discharge. In addition, researchers have tried to prepare composite metal oxide electrode materials. By doping different oxide particles, the porosity of the material can be increased, the wetting ability of the electrolyte to the electrode material can be significantly improved, and the stability of the electrode material can be improved. synergistic effect. However, the effect of improving the charge-discharge performance and cycle performance of such materials is still unsatisfactory. Researchers therefore try to prepare various carbon-supported metal oxide electrode materials. Carbon loading can not only improve the conductivity of the electrode material, but also buffer the volume change of the material during charging and discharging.

Chinese patent CN101811696A discloses a graphene-loaded tricobalt tetroxide nanocomposite material and a preparation method thereof. Get the graphene oxide solution, divalent cobalt salt, and polymer surfactant to mix. Then mix with the alkaline solution with oxidant, stir or ultrasonic for 0.2~5 hours, transfer to a high temperature reaction kettle, anneal at 100~250℃ for 3~30 hours to obtain the product, wash and dry to obtain graphene-supported cobalt trioxide nanometer composite material. The size of cobalt tetroxide is controllable, and the reduction of graphene oxide and the generation of cobalt tetroxide are completed simultaneously.

Chinese patent CN105513834A discloses a preparation method and application of a bacterial cellulose graphene paper loaded tricobalt tetroxide flexible electrode material. Prepare bacterial cellulose slurry; prepare bacterial cellulose graphite paper, prepare a reaction solution containing cobalt salt, soak the bacterial cellulose graphene paper in the reaction solution containing cobalt salt, and make bacterial cellulose graphene paper loaded with three cobalt tetroxide flexible Electrodes, used in supercapacitors. The active material has high specific capacity and excellent mechanical properties of the flexible electrode, and the prepared supercapacitor has good capacitance.

The above invention uses carbon substrates with different shapes to modify the cobalt tetroxide material, but does not involve the composition control of the carbon substrate.

Contents of the invention

The purpose of the present invention is to improve the electrical conductivity of the carbon material through nitrogen atom doping, and at the same time provide lithium ion intercalation active sites to improve lithium storage capacity, cycle performance and rate performance.

The invention is a preparation method of a nitrogen-doped carbon-supported cobalt tetroxide electrode material, the steps of which are as follows:

(1) Mixing: Weigh the carbon source and cobalt source in a mortar according to the mass ratio of 10:1-100:1, grind and mix to obtain a viscous liquid mixture;

(2) Carbonization: put the above liquid mixture into a tube furnace, raise the temperature to 100-400°C for 10-60min in an argon atmosphere, then raise the temperature to 600-1600°C for 60-360min, cool to room temperature, and obtain the precursor body;

(3) Oxidation: The above precursor is heated to 200-700°C in an air atmosphere, kept for 20-120min and then cooled to room temperature to prepare nitrogen-doped carbon-supported cobalt tetroxide electrode material.

The advantage of the invention is that the electrode material of tricobalt tetroxide is modified by adjusting and controlling the composition of the carbon matrix. The ionic liquid containing nitrogen is used as the carbon source. First, the cobalt salt is mixed with the ionic liquid. The cobalt salt is dissolved in the ionic liquid or chemically reacts with the ionic liquid to ensure that the cobalt source and the carbon source are uniformly mixed at the molecular level; After high-temperature carbonization and oxidation, a nitrogen-doped carbon-supported cobalt tetroxide material is obtained. The method for preparing the nitrogen-doped carbon-supported cobalt tetroxide material has a simple process, small particles of cobalt tetroxide and good dispersion, and the nitrogen content in the carbon matrix and the loading capacity of the cobalt trioxide are adjustable.

Description of drawings

Fig. 1 is the process flow diagram of the present invention for preparing nitrogen-doped carbon-supported cobalt tetroxide electrode material, Fig. 2 is the XRD figure of the nitrogen-doped carbon-supported cobalt tetroxide electrode material prepared by the present invention, Fig. 3 is the nitrogen-doped carbon-supported electrode material prepared by the present invention The discharge specific capacity cycle curve of cobalt tetraoxide electrode material.

detailed description

The invention is a preparation method of a nitrogen-doped carbon-supported cobalt tetroxide electrode material, the steps of which are as follows:

(1) Mixing: Weigh the carbon source and cobalt source in a mortar according to the mass ratio of 10:1-100:1, grind and mix to obtain a viscous liquid mixture;

(2) Carbonization: put the above liquid mixture into a tube furnace, raise the temperature to 100-400°C for 10-60min under an argon atmosphere, then raise the temperature to 600-1600°C for 60-360min, cool to room temperature, and obtain the precursor body;

(3) Oxidation: The above precursor is heated to 200-700°C in an air atmosphere, kept for 20-120min and then cooled to room temperature to prepare nitrogen-doped carbon-supported cobalt tetroxide electrode material.

The carbon source described in the above preparation method is an ionic liquid, specifically 1-butyl-3-methylimidazolium tetrafluoroborate, or 1-butyl-3-methylimidazolium dihydrogen phosphate, or 1-butyl Base-3-methylimidazolium nitrate, or 1-butyl-3-methylimidazolium bromide, or 1-ethyl-3-methylimidazolium bromide, or 1-butyl-3-methylhydroxide Imidazolium salt, or 1-dodecyl-3-methylimidazolium hydroxide, or 1-butyl-3-methylimidazolium chloride, or 1-ethyl-3-methylimidazolium dinitrile ammonium salt , or 1-butyl-3-methylimidazole dinitrile amine salt, or 1-octyl-3-methylimidazole dinitrile amine salt, or 1-butyl-2,3-dimethylimidazole dinitrile amine salt, or N-ethylpyridine dinitrile amine salt, or 1-nitrile propyl-3-methylimidazolium chloride salt, or 1-nitrile propyl-3-methylimidazole dinitrile amine salt, or 1-nitrile propyl Base-3-methylimidazole nitrate, or 1-allyl-3-butylimidazole dinitrile amine salt, or 1-allyl-3-hexylimidazolium chloride, or 1-allyl-3- Hexylimidazolium bromide, or a combination of the above ionic liquids.

The cobalt source described in the above preparation method is cobalt nitrate, or cobalt acetate, or cobalt acetylacetonate, or cobalt oxalate, or cobalt sulfate, or cobalt carbonate, or a combination of the above cobalt salts.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

Example 1:

Put 20g of 1-butyl-3-methylimidazolium tetrafluoroborate and 1g of cobalt acetate in a mortar, grind and mix them evenly, put them into a crucible, heat them in a tube furnace to 100°C for 30min under the protection of argon, Then raise the temperature to 700°C for 120 minutes, cool to room temperature; then raise the temperature to 600°C for 30 minutes in an air atmosphere, and cool to room temperature to obtain a nitrogen-doped carbon-supported tricobalt tetroxide electrode material. The electrochemical performance test of the obtained nitrogen-doped carbon-supported cobalt tetroxide electrode material was carried out using CR2025 button cells. 8:1:1 mix evenly, add appropriate amount of NMP (N-methylpyrrolidone) and grind it evenly in an agate mortar to form a viscous jelly mixture, then evenly spread it on a 0.02mm thick copper foil, place it in 100 ℃ vacuum drying for 10 hours, punched into a disc with a diameter of 9mm, the counter electrode is a metal lithium sheet, and the electrolyte is 1mol.L ^- LiPF ₆ /EC:DMC (1:1), wherein EC is ethylene carbonate, DMC is dicarbonate Methyl ester, the diaphragm uses celgard2400 diaphragm, and the assembly is carried out in a glove box filled with an inert atmosphere. The assembled battery is tested for charge and discharge performance with the blue electric battery test system. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material is 866.5mAh/g, and the capacity remains at 457.3 mAh/g after 20 cycles.

Example 2:

Put 20g of 1-butyl-3-methylimidazolium dinitrile ammonium salt and 1g of cobalt acetate in a mortar, grind and mix them evenly, put them into a crucible, heat them in a tube furnace to 100°C for 30min under the protection of argon, and then Raise the temperature to 900°C for 120 minutes, cool to room temperature; then raise the temperature to 450°C for 45 minutes in an air atmosphere, and cool to room temperature to obtain a nitrogen-doped carbon-supported cobalt tetroxide electrode material (see Figure 2 for XRD). The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 904.2mAh/g, and the capacity remained at 679.3 mAh/g after 20 cycles (see Figure 3).

Example 3:

Put 100g of 1-butyl-3-methylimidazolium dihydrogen phosphate and 1g of cobalt acetate in a mortar, grind and mix them evenly, put them into a crucible, heat them in a tube furnace to 100°C for 30min under the protection of argon, and then Raise the temperature to 900°C for 120 minutes, cool to room temperature; then raise the temperature to 450°C for 45 minutes in an air atmosphere, and cool to room temperature to obtain a nitrogen-doped carbon-supported tricobalt tetroxide electrode material. The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 824.8mAh/g, and the capacity remained at 459.5mAh/g after 20 cycles.

Example 4:

Put 15g of 1-butyl-2,3-dimethylimidazolium dinitrile amine salt, 15g of 1-butyl-3-methylimidazolium hydroxide and 1g of cobalt nitrate in a mortar and grind them evenly before putting them into a crucible , heated to 150°C for 30 minutes under the protection of argon in a tube furnace, then heated to 1000°C for 120 minutes, cooled to room temperature; then heated to 450°C for 60 minutes in an air atmosphere, and cooled to room temperature to obtain nitrogen-doped carbon Load tricobalt tetroxide electrode material. The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 1024.3mAh/g, and the capacity remained at 639.2mAh/g after 20 cycles.

Example 5:

Put 15g of N-ethylpyridine dinitrile amine salt, 15g of 1-butyl-3-methylimidazolium hydroxide and 1g of cobalt nitrate in a mortar, grind and mix them evenly, put them in a crucible, and place them in a tube furnace with argon Heating to 150°C for 30 minutes under gas protection, then raising the temperature to 1000°C for 120 minutes, cooling to room temperature; then raising the temperature to 450°C for 60 minutes in an air atmosphere, and cooling to room temperature to obtain nitrogen-doped carbon-supported tricobalt tetroxide electrode material. The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 624.3mAh/g, and the capacity remained at 369.2mAh/g after 20 cycles.

Embodiment 6:

Put 30g of 1-cyanopropyl-3-methylimidazolium chloride salt and 3g of cobalt acetate in a mortar, grind and mix them evenly, put them into a crucible, heat them in a tube furnace to 150°C for 30min under the protection of argon, and then Raise the temperature to 1000°C for 120 minutes, cool to room temperature; then raise the temperature to 450°C for 60 minutes in an air atmosphere, and cool to room temperature to obtain a nitrogen-doped carbon-supported tricobalt tetroxide electrode material. The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 986.7mAh/g, and the capacity remained at 714.7mAh/g after 20 cycles.

Embodiment 7:

Put 20g of 1-butyl-3-methylimidazolium tetrafluoroborate and 1g of cobalt sulfate in a mortar, grind and mix them evenly, put them into a crucible, and heat them in a tube furnace to 100°C for 30min under the protection of argon. Then raise the temperature to 800°C for 120 minutes, cool to room temperature; then raise the temperature to 600°C for 30 minutes in an air atmosphere, and cool to room temperature to obtain a nitrogen-doped carbon-supported tricobalt tetroxide electrode material. The battery was assembled according to the method of Example 1 and tested. Under the condition of charge and discharge rate of 0.1C, the initial discharge specific capacity of the material was 486.7mAh/g, and the capacity remained at 312.2mAh/g after 20 cycles.

Claims (3)

1. A preparation method for a nitrogen-doped carbon-loaded cobalt tetroxide electrode material, characterized in that the steps are: (1) Mixing: Weigh the carbon source and cobalt source in a mortar according to the mass ratio of 10:1-100:1, grind and mix to obtain a viscous liquid mixture; (2) Carbonization: put the above liquid mixture into a tube furnace, raise the temperature to 100-400°C for 10-60min in an argon atmosphere, then raise the temperature to 600-1600°C for 60-360min, cool to room temperature, and obtain the precursor body; (3) Oxidation: The above precursor is heated to 200-700°C in an air atmosphere, kept for 20-120min and then cooled to room temperature to prepare nitrogen-doped carbon-supported cobalt tetroxide electrode material. 2. The preparation method of nitrogen-doped carbon-loaded cobalt tetroxide electrode material according to claim 1, characterized in that said carbon source is an ionic liquid, specifically 1-butyl-3-methylimidazolium tetrafluoroborate , or 1-butyl-3-methylimidazolium dihydrogen phosphate, or 1-butyl-3-methylimidazolium nitrate, or 1-butyl-3-methylimidazolium bromide, or 1-ethyl -3-methylimidazolium bromide, or 1-butyl-3-methylimidazolium hydroxide, or 1-dodecyl-3-methylimidazolium hydroxide, or 1-butyl-3-chloride -Methylimidazolium salt, or 1-ethyl-3-methylimidazole dinitrile amine salt, or 1-butyl-3-methylimidazole dinitrile amine salt, or 1-octyl-3-methylimidazole dinitrile Nitrile amine salt, or 1-butyl-2,3-dimethylimidazole dinitrile amine salt, or N-ethylpyridine dinitrile amine salt, or 1-nitrile propyl-3-methylimidazolium chloride salt, or 1-Nitropropyl-3-methylimidazole dinitrile amine salt, or 1-nitrile propyl-3-methylimidazole nitrate, or 1-allyl-3-butylimidazole dinitrile amine salt, or 1 - Allyl-3-hexylimidazolium chloride, or 1-allyl-3-hexylimidazolium bromide, or a combination of the above ionic liquids. 3. The preparation method of nitrogen-doped carbon-supported cobalt tetroxide electrode material according to claim 1, characterized in that said cobalt source is cobalt nitrate, or cobalt acetate, or cobalt acetylacetonate, or cobalt oxalate, or cobalt sulfate, Or cobalt carbonate, or a combination of the aforementioned cobalt salts.