阅读说明：本技术 一种铜掺杂钒酸盐电极材料及其制备方法和应用 (Copper-doped vanadate electrode material and preparation method and application thereof ) 是由 袁勋龙 董轶凡 夏帆 于 2020-06-08 设计创作，主要内容包括：本发明公开了一种三维网络结构铜掺杂钒酸盐电极材料的制备方法,包括以下步骤：步骤1、将钠源、钒源、铜源用水溶解,得混合液；步骤2、将柠檬酸饱和溶液加入到混合液中,加热,烘干,得干凝胶前躯体；步骤3、将干凝胶前驱体进行煅烧,得三维网络结构铜掺杂钒酸盐电极材料；还提供一种三维网络结构铜掺杂钒酸盐电极材料的制备方法制备的三维网络结构铜掺杂钒酸盐电极材料,还提供一种三维网络结构铜掺杂钒酸盐电极材料制备的钠离子电池正极极片。本发明具有制备工艺简单、电化学性能良好的有益效果。(The invention discloses a preparation method of a copper-doped vanadate electrode material with a three-dimensional network structure, which comprises the following steps: step 1, dissolving a sodium source, a vanadium source and a copper source in water to obtain a mixed solution; step 2, adding the citric acid saturated solution into the mixed solution, heating and drying to obtain a dry gel precursor; step 3, calcining the xerogel precursor to obtain the copper-doped vanadate electrode material with the three-dimensional network structure; the three-dimensional network structure copper-doped vanadate electrode material prepared by the preparation method of the three-dimensional network structure copper-doped vanadate electrode material is also provided, and the sodium ion battery positive pole piece prepared by the three-dimensional network structure copper-doped vanadate electrode material is also provided. The invention has the advantages of simple preparation process and good electrochemical performance.)

1. A preparation method of a copper-doped vanadate electrode material with a three-dimensional network structure is characterized by comprising the following steps: step 1, dissolving a sodium source, a vanadium source and a copper source in water to obtain a mixed solution;

step 2, adding a citric acid solution into the mixed solution, heating and drying to obtain a dry gel precursor, wherein the ratio of the mole number of vanadium elements in a vanadium source to the mole number of citric acid in the citric acid solution is 1-1.5: 3-3.5;

and 3, calcining the xerogel precursor to obtain the copper-doped vanadate electrode material with the three-dimensional network structure.

2. The preparation method of the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the molar ratio of vanadium element, sodium element and copper element in the vanadium source, the sodium source and the copper source is 1-1.5: 1: 1.

3. The method for preparing the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the ratio of the sum of the molar numbers of the vanadium element, the sodium element and the copper element in the vanadium source, the sodium source and the copper source to the molar number of the citric acid in the citric acid solution is 1: 1.

4. The method for preparing the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the vanadium source is one or more of ammonium metavanadate, vanadium pentoxide, vanadyl nitrate and ammonium vanadate.

5. The method for preparing the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the sodium source is one or more of sodium carbonate, sodium bicarbonate, sodium nitrate and sodium hydroxide.

6. The method for preparing the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the copper source is copper nitrate trihydrate.

7. The method for preparing the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the heating temperature in the step 2 is 80-100 ℃, and the heating time is 4-5 h; and (3) drying at the temperature of 80-100 ℃ in the step (2) for 18-24 h.

8. The preparation method of the three-dimensional network structure copper-doped vanadate electrode material according to claim 1, wherein the calcination in the step 3 is carried out in a muffle furnace, the calcination temperature is 400-600 ℃, and the calcination time is 4-7.5 h.

9. The three-dimensional network structure copper-doped vanadate electrode material prepared by the method according to any one of claims 1 to 8.

10. A positive electrode plate of a sodium-ion battery, characterized in that the three-dimensional network structure copper-doped vanadate electrode material of claim 9 is used as an active material of the positive electrode plate of the sodium-ion battery.

Technical Field

The invention relates to the technical field of sodium ion battery materials. More specifically, the invention relates to a copper-doped vanadate electrode material, and a preparation method and application thereof.

Background

Today, the resource is scarce, the advanced energy storage technology becomes one of the standards for measuring the comprehensive national power of a country. In the current energy storage battery system, the lithium ion battery attracts much attention due to its rather high energy density and system flexibility, and has been widely applied in various engineering fields such as electric vehicles, aerospace and the like. However, lithium ion batteries also have certain safety problems, and the high cost and insufficient resources limit the future application of lithium ion batteries, especially in large-scale energy storage systems. Therefore, it is becoming more important to develop battery systems that can replace lithium ion batteries.

It is worth mentioning that the sodium element in the same main group with lithium in the periodic table has the physical and chemical properties similar to lithium, and the sodium element has quite abundant reserves in nature and simple extraction, and is expected to meet the requirement of large-scale energy storage in the future. Compared with the lithium ion battery, the sodium salt raw material of the sodium ion battery has rich reserves and low price; and the sodium ion battery can use low-concentration electrolyte, thereby reducing the cost; because sodium ions do not form alloy with aluminum, the negative electrode can adopt aluminum foil as a current collector, the cost can be further reduced, and the weight is reduced; the sodium ion battery has no over-discharge characteristic and allows the sodium ion battery to discharge to zero volts. However, sodium also has some disadvantages compared to lithium. The most significant disadvantage is that the radius and relative atomic mass of sodium ions are both larger than those of lithium ions, while the standard electrode potential of sodium ions is slightly higher than that of lithium ions. These together result in a sodium ion battery with a lower voltage, a lower diffusion coefficient and Na⁺The intercalation/deintercalation has a significant influence on the crystal structure of the electrode. Therefore, how to find the sodium ion battery electrode material with high capacity, long service life and satisfactory rate performance has important research significance.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide a preparation method of the copper-doped vanadate electrode material with the three-dimensional network structure, the preparation process is simple, the electrochemical performance of the copper-doped vanadate electrode material with the three-dimensional network structure prepared by the preparation method is good, and the application of the copper-doped vanadate electrode material with the three-dimensional network structure on the positive pole piece of the sodium-ion battery is further provided, so that the capacity and the cycling stability of the sodium-ion battery are further improved.

To achieve these objects and other advantages in accordance with the present invention, there is provided a method for preparing a three-dimensional network structure copper-doped vanadate electrode material, comprising the steps of:

step 1, dissolving a sodium source, a vanadium source and a copper source in water to obtain a mixed solution;

step 2, adding a citric acid saturated solution into the mixed solution, heating and drying to obtain a dry gel precursor, wherein the ratio of the mole number of vanadium elements in a vanadium source to the mole number of citric acid in a citric acid solution is 1-1.5: 3-3.5;

and 3, calcining the xerogel precursor to obtain the copper-doped vanadate electrode material with the three-dimensional network structure.

Preferably, the molar ratio of vanadium element, sodium element and copper element in the vanadium source, the sodium source and the copper source is 1-1.5: 1: 1.

Preferably, the ratio of the sum of the number of moles of vanadium, sodium and copper in the vanadium, sodium and copper sources to the number of moles of citric acid in the citric acid solution is 1: 1.

Preferably, the vanadium source is one or more of ammonium metavanadate, vanadium pentoxide, vanadyl nitrate and ammonium vanadate.

Preferably, the sodium source is one or more of sodium carbonate, sodium bicarbonate, sodium nitrate and sodium hydroxide.

Preferably, the copper source is copper nitrate trihydrate.

Preferably, the heating method in the step 2 is water bath heating, the heating temperature is 80-100 ℃, and the heating time is 4-5 hours; and (3) drying at the temperature of 80-100 ℃ in the step (2) for 18-24 h.

Preferably, the calcination in the step 3 is carried out in a muffle furnace, the calcination temperature is 400-600 ℃, and the calcination time is 4-7.5 h;

also provides a preparation method of the three-dimensional network structure copper-doped vanadate electrode material.

The positive pole piece of the sodium-ion battery is also provided, and a copper-doped vanadate electrode material with a three-dimensional network structure is used as an active material of the positive pole piece of the sodium-ion battery.

The invention at least comprises the following beneficial effects:

in the preparation process of the three-dimensional network structure copper-doped vanadate electrode material, citric acid is added as a metal ion complexing agent, so that metal hydroxide precipitation is not easy to generate; by using a simple hydrothermal method, Na is made⁺、Cu²⁺And VO^3-Self-assembly into NaCu (VO)₃)₃And further polymerized into NaCuV_xO_y·zH₂O (xerogel precursor) adopts a hydrothermal method, so that the reaction temperature is low, the reaction time is short, the granularity of a reaction product is uniform, the size is small, and the reaction process is easy to control; the xerogel precursor is calcined in the air to obtain NaCuV_xO_y·zH₂O is calcined to fully generate Cu-doped NaVO₃And obtaining Cu-doped NaVO after calcination₃High purity and good crystallinity, and the Cu-doped NaVO is generated by calcination₃A three-dimensional network structure; the prepared three-dimensional network structure copper-doped vanadate electrode material not only has excellent electrochemical storage performance, but also has excellent cycling stability, and a novel preparation method is provided for preparing a high-performance electrode material of a sodium-ion battery.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is an XRD pattern of a copper-doped vanadate electrode material with a three-dimensional network structure according to example 1 of the present invention;

FIG. 2 is an SEM image of a three-dimensional network structure copper-doped vanadate electrode material according to example 1 of the invention;

FIG. 3 is an SEM image of a three-dimensional network structure copper-doped vanadate electrode material according to example 1 of the invention;

FIG. 4 is a SAED diagram of a three-dimensional network structure copper-doped vanadate electrode material according to example 1 of the present invention;

FIG. 5 shows that the three-dimensional network structure of the copper-doped vanadate electrode material of example 1 is 0.5Ag^-1A plot of cycling performance at current density;

FIG. 6 shows a three-dimensional network structure of 2Ag doped vanadate electrode material in accordance with example 1 of the present invention^-1Coulombic efficiency plots at current density;

FIG. 7 shows that the three-dimensional network structure of the copper-doped vanadate electrode material of example 1 is formed at 0.1, 0.2, 0.5, 1 and 2Ag^-1Graph of rate performance at current density.

Detailed Description

The present invention is further described in detail below with reference to the drawings and examples so that those skilled in the art can practice the invention with reference to the description.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

< example 1>

The preparation method of the three-dimensional network structure copper-doped vanadate electrode material comprises the following steps:

step 1, mixing 1.0 × 10^-3mol of NH₄VO₃、5.0×10^-4mol of Na₂CO₃And 1.0X 10^-3mol of Cu (NO)₃)₂·3H₂Adding O into a beaker filled with 50mL of distilled water, and fully stirring until the mixture is dissolved to form a mixed solution;

step 2, adding the mixture containing 3X 10^-3The preparation method comprises the following steps of (1) heating and stirring a citric acid saturated solution of mol citric acid in a water bath at 80 ℃ for 5 hours, and then drying in a ventilation drying oven at 80 ℃ for 24 hours to form a dry gel precursor;

and 3, putting the dry gel precursor into a muffle furnace for calcining at 500 ℃ for 6 hours to obtain the copper-doped vanadate electrode material with the three-dimensional network structure.

The three-dimensional network structure copper-doped vanadate electrode material prepared in example 1 was subjected to an X-ray diffractometer test having an X-ray diffraction pattern (XRD) and Cu-doped LiVO as shown in FIG. 1₃Very similar (Cu doped NaVO)₃There is no corresponding PDF card for the moment), but the peak position shifts somewhat, due to Na⁺Radius ratio of (Li)⁺Large radius of (3), Cu-doped LiVO₃The positions and the intensities of most diffraction peaks of the diffraction peaks are the same as those of JCPDS18-0726And (4) matching.

Scanning electron microscope tests are carried out on the three-dimensional network structure copper-doped vanadate electrode material prepared in the embodiment 1, the test patterns are shown in fig. 2 and fig. 3, and Scanning Electron Microscope (SEM) pictures show that the obtained product is granular, the particle size range is wide, and the morphology size is 0.1-0.5 μm; cu doped NaVO can be clearly seen₃The particles are interconnected and interwoven to form a porous network structure.

The Selected Area Electron Diffraction (SAED) test was performed on the three-dimensional network structure copper-doped vanadate electrode material prepared in example 1, and the test spectrum is shown in fig. 4, and it can be seen from the Selected Area Electron Diffraction (SAED) graph that the synthesized sample has a single crystal structure.

< example 2>

This example is essentially the same as example 1 except that in step 1, VO is added₂NO₃Is 1.5X 10^-3mol、NaHCO₃Is 1 × 10^-3mol; in step 2, a catalyst containing 3.5X 10 carbon atoms is added^-3The temperature of the hydrothermal reaction of the citric acid solution of the mol citric acid is 100 ℃, the time is 4 hours, the drying temperature is 100 ℃, and the drying time is 18 hours.

The three-dimensional network structure copper-doped vanadate electrode material is subjected to X-ray test, scanning electron microscope test, selective area electron diffraction and button cell electrochemical performance test, and the X-ray test shows that the prepared product is Cu-dopedHetero NaVO₃Scanning electron microscope tests show that the obtained products are granular, are connected with each other and are staggered to form a three-dimensional network structure, and a Selected Area Electron Diffraction (SAED) image can clearly show that the synthesized sample is of a single-crystal structure.

< example 3>

This example is substantially the same as example 1 except that in step 1, (NH) is added₄)₃VO₄Is 1 × 10^-3mol，NaHCO₃Is 1 × 10^-3mol; in step 2, the calcination temperature was 400 ℃ and the calcination time was 7.5 h.

The three-dimensional network structure copper-doped vanadate electrode material is subjected to X-ray test, scanning electron microscope test, selective area electron diffraction and button cell electrochemical performance test, and the X-ray test shows that the prepared product is Cu-doped NaVO₃Scanning electron microscope tests show that the obtained products are granular, are connected with each other and are staggered to form a three-dimensional network structure, and a Selected Area Electron Diffraction (SAED) image can clearly show that the synthesized sample is of a single-crystal structure.

< example 4>

This example is essentially the same as example 1 except that in step 1, V is added₂O₅Is 5.0X 10^-4And the calcining temperature is 600 ℃, and the calcining time is 4 h.

The three-dimensional network structure copper-doped vanadate electrode material is subjected to X-ray test, scanning electron microscope test, selective area electron diffraction and button cell electrochemical performance test, and the X-ray test shows that the prepared product is Cu-doped NaVO₃Scanning electron microscope tests show that the obtained products are granular, are connected with each other and are staggered to form a three-dimensional network structure, and a Selected Area Electron Diffraction (SAED) image can clearly show that the synthesized sample is of a single-crystal structure.

< comparative example 1>

Based on NaVO₃The positive electrode material of the sodium ion battery is 100mA g^-1The initial specific discharge capacity measured under the current density is 211mAh g^-1Initial chargingThe specific capacity is 219mAh g^-1At 2A g^-1The coulombic efficiency measured at the current density was 82%.

< comparative example 2>

Based on V₂O₅The sodium ion battery of the nano-wire anode material is 100mA g^-1The initial specific discharge capacity measured under the current density is 318mAh g^-1Initial charging specific capacity of 257mAh g^-1At 2A g^-1The coulombic efficiency measured at the current density was 51%.

< electrochemical Performance test >

Electrochemical performance tests were performed on the three-dimensional network structure copper-doped vanadate electrode materials prepared in examples 1 to 4, and active materials (Cu-doped NaVO) were selected₃) The mass ratio of the conductive agent (acetylene black) to the binder (polytetrafluoroethylene solution) is 7:2: 1. Firstly, weighing 35mg of active substance and 10mg of acetylene black in agate grinding, adding a proper amount of isopropanol, continuously grinding until no granular sensation exists, finally adding 6.5 mu L of polytetrafluoroethylene solution to bond the active substance and the acetylene black together, then pressing the mixture into a membrane with uniform thickness on a roll-to-roll machine, and then forming the membrane with the area of about 1cm²The small disks were dried in an oven at 80 ℃ for 24 h. Using the pressed diaphragm as an anode, a metal sodium sheet as a cathode, a stainless steel mesh as a current collector, a housing as a CR2016 type battery housing, diaphragm paper as a Celgard 2400 microporous polypropylene film, and 1.0mol/L NaClO as electrolyte₄The lithium ion battery was assembled in an argon-filled glove box with a solution of Ethylene Carbonate (EC)/dimethyl carbonate (DMC) (volume ratio EC: DMC ═ l: l), and the battery was allowed to stand for one day before the battery performance test was performed. The results are shown in Table 1.

Initial discharge specific capacity of the button cell assembled by the three-dimensional network structure copper-doped vanadate electrode material prepared in the embodiments 1 to 4 is 100mA g^-1Initial specific discharge capacity in a charge-discharge test performed at a current density;

initial charging specific capacity of the button cell assembled by the three-dimensional network structure copper-doped vanadate electrode material prepared in the embodiments 1-4 at 100mA g^-1Initial in charge and discharge test conducted at Current DensityInitial charging specific capacity;

charge-discharge specific capacity coulombic efficiency of button cell assembled by three-dimensional network structure copper-doped vanadate electrode material prepared in embodiments 1-4 is 2A g^-1The cycle performance test parameters are carried out under the current density, and the cycle times are 500 times;

the rate capability of the button cell assembled by the three-dimensional network structure copper-doped vanadate electrode material prepared in the embodiments 1-4 is 0.1A g^-1、0.2A g^-1、0.5A g^-1、1A g^-1And 2A g^-12Ag in charge and discharge test performed at Current Density^-1Initial specific charge capacity;

TABLE 1