阅读说明：本技术 铌钨氧化物电极材料及其制备和应用 (Niobium-tungsten oxide electrode material and preparation and application thereof ) 是由 刘金平 叶一桦 周金泉 于 2020-07-31 设计创作，主要内容包括：本发明涉及一种铌钨氧化物电极材料及其制备方法,其化学式为W<Sub>6</Sub>Nb<Sub>14</Sub>O<Sub>53</Sub>,为多孔微米球结构,微米球结构表面具有丰富的多孔位点,所述铌钨氧化物微米球半径为1～2微米之间。所述的铌钨氧化物电极材料的制备方法,包括如下步骤：将铌盐、氢氟酸、异丙醇、钨盐在室温下搅拌均匀得到混合溶液；将混合溶液密封加热,保持；待混合溶液自然冷却后收集粉末,洗涤后烘干；将烘干后的活性物质收集,在空气中加热后退火。本发明的有益效果：可以使电解液与活性材料充分接触,增加电解液的渗透能力,减小界面电阻,使得整个结构更加稳定,不会因为循环充放电而坍塌；使用简单的低温水热法合成铌钨氧化物材料,具有可重复性高、过程简单等优点。(The invention relates to a niobium tungsten oxide electrode material and a preparation method thereof, wherein the chemical formula of the material is W 6 Nb 14 O 53 The niobium-tungsten oxide microsphere is of a porous microsphere structure, the surface of the microsphere structure is provided with abundant porous sites, and the radius of the niobium-tungsten oxide microsphere is 1-2 micrometers. The preparation method of the niobium-tungsten oxide electrode material comprises the following steps: uniformly stirring niobium salt, hydrofluoric acid, isopropanol and tungsten salt at room temperature to obtain a mixed solution; sealing and heating the mixed solution, and keeping; after the mixed solution is naturally cooled, collecting powder, washing and drying; and collecting the dried active substances, heating in air and then annealing. The invention has the beneficial effects that: can make the electrolyte and the active materialThe electrolyte is fully contacted, the permeability of the electrolyte is increased, the interface resistance is reduced, the whole structure is more stable, and collapse caused by cyclic charge and discharge is avoided; the niobium tungsten oxide material is synthesized by using a simple low-temperature hydrothermal method, and has the advantages of high repeatability, simple process and the like.)

1. Niobium tungsten oxide electrode material with chemical formula W₆Nb₁₄O₅₃The niobium-tungsten oxide microsphere is of a porous microsphere structure, the surface of the microsphere structure is provided with abundant porous sites, and the radius of the niobium-tungsten oxide microsphere is 1-2 micrometers.

2. The method for preparing the niobium tungsten oxide electrode material as claimed in claim 1, comprising the steps of:

(1) uniformly stirring niobium salt, hydrofluoric acid, isopropanol and tungsten salt at room temperature to obtain a mixed solution;

(2) sealing and heating the mixed solution to 220 ℃ at 180 ℃ for 12-48 hours; after the mixed solution is naturally cooled, collecting powder, washing and drying;

(3) collecting the dried active substances, heating in air, and annealing to obtain W₆Nb₁₄O₅₃。

3. The method for preparing niobium tungsten oxide electrode material according to claim 2, wherein said niobium salt is niobium chloride or niobium fluoride and said tungsten salt is tungsten chloride or tungsten fluoride.

4. The method of claim 2, wherein the volume ratio of the amount of the niobium salt to the isopropyl alcohol in the solution is 0.03 to 0.04mol/L, the volume ratio of the amount of the hydrofluoric acid in the solution to the isopropyl alcohol is 13 to 15g/L, and the volume ratio of the amount of the tungsten salt to the isopropyl alcohol in the solution is 0.009 to 0.014 mol/L.

5. The method for preparing niobium tungsten oxide electrode material as claimed in claim 2, wherein said heating temperature is 850-950 ℃.

6. Use of the niobium tungsten oxide electrode material according to claim 1 as negative electrode material for lithium ion batteries.

Technical Field

The invention relates to a niobium-tungsten oxide electrode material and a preparation method thereof, which belong to the fields of electrochemistry, materials science, energy sources and the like and can be applied to a cathode material of an organic lithium ion battery (or other mixed electrochemical energy storage devices).

Background

With the development of the times and the improvement of the living standard of human beings, the technical requirements of people on portable energy storage equipment are higher and higher. Among them, the lithium ion battery has advantages of high energy density, high voltage capacitance, no memory effect, and good cycle stability, so that the secondary battery is successfully commercialized, and has become a main power source of portable electronic devices and electric vehicle systems. Commercial graphite is a lithium ion battery cathode material widely used in commercial applications at present due to its large specific capacity and low cost, but due to its low working potential, a solid electrolyte interface film is easily generated in the charging and discharging process, and lithium dendrite is generated to cause a battery short circuit, which has a very serious safety problem.

Niobium-based oxide becomes a research hotspot of high-performance cathode materials in the current electrochemical energy storage field due to the specific structural advantages and good electrochemical performance of niobium-based oxide, and is rapidly developed into one of the most promising materials in the fields of lithium/sodium ion batteries, fuel cells, super capacitors and the like in recent years. However, the poor intrinsic conductivity of niobium reduces electron transfer during lithium intercalation and deintercalation, which limits the development of niobium-based oxides in terms of high rate capability, high theoretical capacity and cycle performance to some extent.

Disclosure of Invention

The invention aims to provide a novel niobium tungsten oxide electrode material and a preparation method thereof, and the obtained porous microspherical niobium tungsten oxide has good electrochemical performance, especially outstanding high-rate performance and cycle performance, when being used as a negative electrode material of an organic lithium ion battery (or other lithium ion energy storage devices).

In order to achieve the purpose, the invention adopts the technical scheme that: niobium tungsten oxide electrode material with chemical formula W₆Nb₁₄O₅₃The niobium-tungsten oxide microsphere is of a porous microsphere structure, the surface of the microsphere structure is provided with abundant porous sites, and the radius of the niobium-tungsten oxide microsphere is 1-2 micrometers.

The preparation method of the niobium-tungsten oxide electrode material comprises the following steps:

(1) uniformly stirring niobium salt, hydrofluoric acid, isopropanol and tungsten salt at room temperature to obtain a mixed solution;

(2) sealing and heating the mixed solution to 220 ℃ at 180 ℃ for 12-48 hours; after the mixed solution is naturally cooled, collecting powder, washing and drying;

(3) collecting the dried active substances, heating in air, and annealing to obtain W₆Nb₁₄O₅₃。

According to the scheme, the niobium salt is niobium chloride or niobium fluoride, and the tungsten salt is tungsten chloride or tungsten fluoride.

According to the scheme, the volume ratio of the niobium salt substance to the isopropanol in the solution is 0.03-0.04mol/L, the volume ratio of the hydrofluoric acid substance to the isopropanol in the solution is 13-15g/L, and the volume ratio of the tungsten salt substance to the isopropanol in the solution is 0.009-0.014 mol/L.

According to the scheme, the heating temperature is 850-950 ℃.

The electrode material is used as a negative electrode material of a lithium ion battery.

The niobium salt reacts with hydrofluoric acid to be dissolved, Nb5+ ions are formed in the solution, and then the niobium salt is fully mixed and stirred with isopropanol solution containing W6 +. During stirring, air is isolated, and the W6+ is prevented from reacting with oxygen to generate WO 3. Stirring, transferring to a polytetrafluoroethylene lining, and heating in a hydrothermal kettle for reaction. And (3) carrying out hydrothermal reaction to generate niobium tungsten oxide powder containing chloride ions and fluoride ions, washing the powder, drying, and then annealing at high temperature in air to remove the chloride ions and the fluoride ions in the electrode material and improve the crystallinity of the material.

The invention has the beneficial effects that:

(1) the invention synthesizes a new niobium-tungsten oxide electrode material by using a hydrothermal method, and the poor conductivity of the traditional niobium-based oxide is changed by adding tungsten element, so that the niobium-tungsten oxide electrode material has good electrochemical performance in a lithium battery;

(2) the porous microsphere structure can ensure that the electrolyte is fully contacted with the active material, the permeability of the electrolyte is increased, the interface resistance is reduced, the whole structure is more stable, and the collapse caused by cyclic charge and discharge is avoided;

(3) the niobium-tungsten oxide material synthesized by the simple low-temperature hydrothermal method has the advantages of high repeatability, simple process and the like, and can be applied to industrial production, so that the niobium-tungsten oxide material has wide application prospect in the fields of various new energy sources and new materials such as energy storage materials and advanced functional material preparation.

Drawings

FIG. 1 is an X-ray diffraction pattern of a powdered electrode niobium tungsten oxide material at optimum tungsten chloride addition and optimum temperature for production of example 1 in accordance with the invention;

FIG. 2 is an electron microscope image of the niobium tungsten oxide material of the powder electrode at the optimum tungsten chloride addition and the optimum temperature prepared in example 1 of the present invention;

FIG. 3 is a graph showing the comparison of rate capability of tungsten chloride (0.200, 0.230, 0.260g) prepared in example 2 of the present invention in different amounts for synthesizing a negative electrode material of a lithium ion battery;

FIG. 4 is a graph showing the comparison of the rate capability of a lithium ion battery cathode material prepared in example 3 of the present invention with different added niobium salts (niobium pentachloride, niobium pentabromide);

FIG. 5 is a graph comparing rate performance when active materials treated at different annealing temperatures (850, 900, 950 ℃) prepared in example 4 of the present invention are used as negative electrode materials of lithium ion batteries;

FIG. 6 is a graph showing the rate performance of the lithium ion battery negative electrode material with the active material synthesized in the state of the optimum tungsten chloride addition amount (0.230g) and the optimum annealing temperature (900 ℃) prepared in example 5 of the present invention.

FIG. 7 is a graph showing the cycle performance of the lithium ion battery negative electrode material with the active material synthesized in the state of the optimum addition amount (0.230g) of tungsten chloride and the optimum annealing temperature (900 ℃) prepared in example 6 of the present invention.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.