CN108878841A - A kind of sodium-ion battery anode composite material V2O5/NaV6O15Preparation method - Google Patents

Abstract

The invention discloses a preparation method of V ₂ O ₅ /NaV ₆ O ₁₅ , a positive electrode composite material of a sodium ion battery. The preparation method of the positive electrode composite material V ₂ O ₅ /NaV ₆ O ₁₅ for a sodium ion battery is to disperse the vanadium oxide into an aqueous solution of sodium hydroxide with a concentration of 0.01-0.5 mol/L to obtain a suspension, and to prepare the yellow suspension in Perform hydrothermal reaction at 120-220°C for 2-24h, cool naturally to room temperature, filter and dry to obtain precursor powder, heat the precursor to 300-500°C in air and calcinate to obtain V ₂ O ₅ /NaV ₆ O ₁₅ composite material. The V ₂ O ₅ /NaV ₆ O ₁₅ composite material prepared by the method of the present invention is used as the positive electrode material of a sodium ion battery, has high discharge specific capacity, good cycle performance, and long service life, and the preparation method requires simple equipment and low reaction time. The condition is mild, the time consumption is short, the environment is friendly, the production cost is low, and it is suitable for large-scale industrial production.

Description

A kind of preparation method of sodium ion battery cathode composite material V2O5/NaV6O15

technical field

The invention belongs to the technical field of preparation of positive electrode materials for sodium ion batteries, and in particular relates to a method for preparing a V ₂ O ₅ /NaV ₆ O ₁₅ composite material for the positive electrode materials of sodium ion batteries.

Background technique

Lithium-ion batteries have been widely used in portable electronic devices and electric vehicles due to their high energy density and power density, long cycle life, low self-discharge, and environmental friendliness. However, lithium reserves are very limited, and it is difficult to meet the needs of large-scale development in the future. Therefore, finding a secondary battery that can replace lithium-ion batteries has important practical significance for human life and development.

Sodium and lithium are the same main group elements. Not only do they have similar chemical properties, but also sodium is abundant on the earth and the price is low. Therefore, sodium-ion batteries are a new type of battery that is more suitable for large-scale energy storage than lithium-ion batteries. Energy storage battery. In the sodium-ion battery system, the cathode material plays a decisive role in the safety, energy density, cycle life and cost of the battery. Therefore, finding suitable cathode materials is very important for the development and application of Na-ion batteries.

Vanadium pentoxide (V ₂ O ₅ ) with a layered structure is considered to be a very promising cathode material for sodium-ion batteries due to its large theoretical capacity (236mAh/g), abundant reserves and low price. However, vanadium pentoxide has low electronic conductivity and ionic conductivity, and its structure is unstable during the process of intercalating sodium ions, resulting in low reversible capacity and poor rate performance.

Sodium vanadate (NaV ₆ O ₁₅ ) has a channel structure and good ion transferability, and its structure is relatively stable in the process of sodium ion intercalation, so it has good cycle performance as a cathode material for sodium ion batteries, but its specific capacity is relatively low. Low.

By in situ preparation of V ₂ O ₅ /NaV ₆ O ₁₅ composites, taking advantage of the synergistic effect between V ₂ O ₅ and NaV ₆ O ₁₅ materials, good electrochemical performance is expected to be obtained.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a sodium ion battery positive electrode composite material with simple process, convenient operation, environmental protection, good cycle performance and long service life.

The purpose of the present invention is achieved through the following technical solutions:

The preparation method of the positive electrode composite material V ₂ O ₅ /NaV ₆ O ₁₅ for a sodium ion battery is to disperse the vanadium oxide into an aqueous sodium hydroxide solution with a concentration of 0.01-0.5 mol/L to obtain a suspension, and to prepare the suspension at 120 Perform hydrothermal reaction at -220°C for 2-24h, cool naturally to room temperature, filter and dry to obtain precursor powder, heat the precursor to 300-500°C in air and calcinate to obtain V ₂ O ₅ /NaV ₆ O ₁₅ composite Material.

Specifically, the molar ratio of added vanadium oxide to sodium hydroxide is n(V):n(Na)=8-1.

Specifically, the vanadium oxide is selected from one or more of VO, VO ₂ , V ₂ O ₃ , and V ₂ O ₅ .

Specifically, the heating rate of the calcination is 1-10°C/min, and the calcination time is 0.5-6h.

In the preparation method of the present invention, there is no addition of other impurities and discharge of harmful gases in the whole process, and it is a simple and green preparation method.

After the vanadium oxide selected in the present invention is dispersed in sodium hydroxide solution, sodium is intercalated through hydrothermal reaction to obtain VOx/NayVOz precursor, which can be calcined in air to obtain V ₂ O ₅ /NaV ₆ O ₁₅ composite materials.

The V ₂ O ₅ /NaV ₆ O ₁₅ composite material prepared by the present invention is used as the positive electrode material of the sodium ion battery, has high discharge specific capacity, good cycle performance, long service life, and the preparation method requires simple equipment and reaction conditions Mild, short time-consuming, environmentally friendly, low production cost, suitable for large-scale industrial production.

Description of drawings

FIG. 1 is a refined XRD pattern of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite prepared in Example 1 of the present invention.

Fig. 2 is a SEM image of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite material prepared in Example 1 of the present invention.

Fig. 3 is a TEM image of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite material prepared in Example 1 of the present invention.

Fig. 4 is a cycle performance diagram of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite prepared in Example 1 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific experimental examples, rather than limiting the present invention.

Example 1:

Disperse 0.5g of vanadium dioxide powder into 15mL of aqueous sodium hydroxide solution with a concentration of 0.1mol/L, pour the dispersion into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 180°C for 6 hours, and filter the precipitate after cooling to room temperature. Dry at 60°C to obtain the precursor powder. The precursor is heated to 350°C at a rate of 1°C/min in the air and kept at 350°C for 4 hours. After cooling to room temperature, V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposites are obtained. Material. FIG. 1 shows the refined XRD pattern of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite prepared in Example 1. The XRD results in Figure 1 show that the material synthesized in this example is a composite material composed of V ₂ O ₅ (space group: Pmmn) with an orthorhombic structure and NaV ₆ O ₁₅ (space group: A2/m) with a monoclinic structure , where the mass fractions of V ₂ O ₅ and NaV ₆ O ₁₅ are 68.675% and 31.325%, respectively. What Fig. 2 shows is the SEM image of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposites prepared in Example 1, and Fig. 3 shows the TEM of the V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposites prepared in Example 1 picture. It can be seen from Fig. 2 and Fig. 3 that the V ₂ O ₅ /NaV ₆ O ₁₅ composite material synthesized in this example has a nanoribbon shape. Nanostructures can not only shorten the distance of sodium ion diffusion and electron transmission, but also increase the contact area between electrode materials and electrolyte, reduce polarization, and improve the utilization efficiency of materials, thereby effectively improving the electrochemical performance of electrode materials.

The V ₂ O ₅ /NaV ₆ O ₁₅ composite material prepared by the method of the present invention is used as the positive electrode of the sodium ion battery, and the process of making a button battery is as follows: the V ₂ O ₅ /NaV ₆ O ₁₅ composite material prepared in the embodiment of the present invention After mixing evenly with acetylene black and polyvinylidene fluoride (PVDF) adhesive according to the mass ratio of 7:2:1, disperse in N-methylpyrrolidone (NMP) solution to obtain a pasty mixture; The mixture was coated on aluminum foil and dried under vacuum at 120 °C overnight as the positive electrode of a sodium-ion button cell (model 2025), with metallic sodium flakes as the negative electrode and Whatman glass fiber as the separator, 1M _NaClO dissolved in ethylene carbonate/carbonic acid Dimethyl ester (EC/DMC) (1:1, volume ratio) was used as the electrolyte, and button cells were assembled in a glove box filled with high-purity argon (Mikrouna, MKSS1-1305-0838). The charge and discharge performance test of the battery is carried out at room temperature on a blue electric test system of the model CT2001A produced in Wuhan, and the test voltage range is 4-1.5V (referenced to Na ⁺ /Na).

The V ₂ O ₅ /NaV ₆ O ₁₅ nano-composite material prepared in this example is used as the positive electrode of the sodium ion battery, and the button battery (2025 model) is made according to the above method, and the current at 100mA/g is measured in the blue electric test system The electrochemical performance under density is shown in Figure 4; it can be seen from Figure 4 that the initial discharge specific capacity of the synthesized V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposite material reaches 160mAh/g; the second discharge specific capacity is 145mAh/g, and its capacity retention is as high as 64% after 100 charge-discharge cycles; this indicates that the synthesized V ₂ O ₅ /NaV ₆ O ₁₅ nanocomposites have high specific capacity and good cycle stability.

Example 2:

Disperse 0.5g vanadium dioxide powder into 15mL aqueous sodium hydroxide solution with a concentration of 0.2mol/L, pour the dispersion liquid into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 180°C for 2 hours, and filter the precipitate after cooling to room temperature. Dry at 60°C to obtain the precursor powder. The precursor is heated to 350°C at a heating rate of 5°C/min in the air and kept at 350°C for 4 hours. After cooling to room temperature, V ₂ O ₅ /NaV ₆ O ₁₅ composite is obtained. Material.

Example 3:

Disperse 0.5g of vanadium dioxide powder into 15mL of aqueous sodium hydroxide solution with a concentration of 0.1mol/L, pour the dispersion into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 220°C for 2 hours, and filter the precipitate after cooling to room temperature. Dry at 60°C to obtain the precursor powder. The precursor is heated to 350°C at a heating rate of 1°C/min in the air and kept at 350°C for 4 hours. After cooling to room temperature, V ₂ O ₅ /NaV ₆ O ₁₅ composite is obtained. Material.

Example 4:

Disperse 0.5g of vanadium dioxide powder into 15mL of aqueous sodium hydroxide solution with a concentration of 0.1mol/L, pour the dispersion into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 120°C for 24 hours, and filter the precipitate after cooling to room temperature. Dry at 60°C to get the precursor powder. The precursor is heated to 500°C at a heating rate of 10°C/min in the air and kept at 500°C for 0.5 hours. After cooling to room temperature, V ₂ O ₅ /NaV ₆ O ₁₅ composite is obtained. Material.

Example 5:

Disperse 0.5g vanadium pentoxide powder into 15mL aqueous sodium hydroxide solution with a concentration of 0.1mol/L, pour the dispersion into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 180°C for 6 hours, cool to room temperature, and filter the precipitate , dry at 60°C to get the precursor powder, the precursor is heated up to 350°C at a rate of 1°C/min in the air and kept at 350°C for 4 hours, then cooled to room temperature to obtain V ₂ O ₅ /NaV ₆ O ₁₅ composite material.

Embodiment 6:

Disperse 0.25g of vanadium dioxide and 0.25g of vanadium pentoxide powder into 15mL of 0.1mol/L aqueous sodium hydroxide solution, pour the dispersion into a hydrothermal reaction kettle, conduct a hydrothermal reaction at 180°C for 6 hours, and cool After reaching room temperature, filter the precipitate and dry it at 60°C to obtain the precursor powder. The precursor is heated to 350°C in air at a heating rate of 1°C/min and kept at 350°C for 4 hours. After cooling to room temperature, V ₂ O is obtained. ₅ /NaV ₆ O ₁₅ composites.

Claims (4)

1. a kind of sodium-ion battery anode composite material V₂O₅/NaV₆O₁₅Preparation method, it is characterised in that：

Barium oxide is distributed in the sodium hydrate aqueous solution that concentration is 0.01-0.5mol/L and obtains suspension, suspension is existed 120-220 DEG C of progress hydro-thermal reaction 2-24h, after cooled to room temperature, filtering, dry precursor powder exist presoma It is warming up to 300-500 DEG C of calcining in air, obtains V₂O₅/NaV₆O₁₅Composite material.

2. sodium-ion battery anode composite material V according to claim 1₂O₅/NaV₆O₁₅Preparation method, it is characterised in that： The molar ratio of added barium oxide and sodium hydroxide is n (V):N (Na)=8-1.

3. sodium-ion battery anode composite material V according to claim 1₂O₅/NaV₆O₁₅Preparation method, it is characterised in that： The barium oxide is selected from VO, VO₂、V₂O₃、V₂O₅One of or it is a variety of.

4. sodium-ion battery anode composite material V according to claim 1₂O₅/NaV₆O₁₅Preparation method, it is characterised in that： The heating rate of calcining is 1-10 DEG C/min, calcination time 0.5-6h.