Preparation method of high-rate vanadium-doped negative electrode material

Abstract

The invention discloses a high-magnification vanadium-doped negative electrode material preparation method, which comprises: dissolving niobium oxalate in a strong acid solution, adding ammonium ferric citrate to the acidic niobium oxalate solution to obtain a reaction solution, transferring to a reaction kettle, carrying out a constant temperature reaction, placing in a box-type furnace, and calcining to obtain the high-magnification vanadium-doped negative electrode material. And calcining and doping vanadium ions to obtain the vanadium-doped negative electrode material. The iron-niobium oxide is selected as the negative electrode material and calcined to dope the vanadium element in the iron-niobium oxide, and the negative electrode material can still maintain relatively good cycling stability, rate capability and safety in a high-voltage environment by utilizing the lithium intercalation stability of the iron-niobium oxide, a lithium storage mechanism and a relatively high working voltage platform of the iron-niobium oxide; and the migration potential barrier of lithium ions in the iron-niobium oxide is reduced by doping vanadium ions, so that the rate capability of the iron-niobium oxide and the cycling stability under the high rate condition are improved.

Description

Technical Field

[0001] The invention relates to the field of lithium batteries, and in particular to a method for preparing a high-rate vanadium-doped negative electrode material. Background Art

[0002] Lithium-ion battery is a secondary battery that mainly relies on the movement of lithium ions between the positive electrode and the negative electrode to work. + Insertion and deinsertion back and forth between the two electrodes: During charging, Li + It is extracted from the positive electrode and embedded in the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. Secondary batteries represented by lithium-ion batteries have the advantages of high operating voltage, high energy density, good safety and no memory effect, and have achieved great success in the fields of portable electronic devices, new energy vehicles and hybrid vehicles.

[0003] In recent years, as new energy vehicles have been widely loved by consumers, their penetration rate has continued to increase, and the technology of lithium-ion batteries has also been continuously improved. Improving the energy density and fast charging level of lithium-ion batteries is an important way to improve the efficiency of new energy vehicles. As the charging power of new energy vehicles increases from 250kW to 350kW, and the charging voltage increases from 400V to 800V, the negative electrode materials currently used in lithium-ion batteries on the market cannot provide lithium-ion batteries with good rate performance, first coulomb efficiency and cycle performance under high-voltage environments. To this end, it is necessary to develop a new negative electrode material to solve the above problems. Summary of the invention

[0004] In view of this, the present invention aims to address the deficiencies in the prior art, and its main purpose is to provide a method for preparing a high-rate vanadium-doped negative electrode material, which can effectively solve the problem that the existing lithium-ion battery negative electrode materials cannot provide lithium-ion batteries with good rate performance, first coulombic efficiency and cycle performance under high-voltage environments.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a high-rate vanadium-doped negative electrode material comprises the following steps:

[0007] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 24-48 hours, the reaction temperature is 100-200° C., and then centrifugally washing and drying to obtain a synthetic product;

[0008] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination, the calcination time is 5-7 hours, the calcination temperature is 950-1150° C., and after natural cooling, iron niobium oxide is obtained;

[0009] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 300-400 r / min for 1-2 h. After ball milling, the ball milling product is evaporated to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 5-7 h, the calcination temperature is 950-1150° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0010] As a preferred solution, the strong acid solution consists of 15 ml of pure water and 1 ml of concentrated nitric acid.

[0011] As a preferred embodiment, the concentration of the concentrated nitric acid is 8 mol / L.

[0012] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0013] By selecting iron niobium oxide as the negative electrode material and calcining it to dope vanadium into the iron niobium oxide, and by utilizing the stability of lithium insertion, lithium storage mechanism and higher working voltage platform of iron niobium oxide, the negative electrode material can still maintain good cycle stability, rate performance and safety under high-voltage environment. Combined with reducing the migration barrier of lithium ions in iron niobium oxide by doping with vanadium ions, the rate performance of iron niobium oxide and the cycle stability under high-rate conditions are improved.

[0014] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with specific embodiments. DETAILED DESCRIPTION

[0015] The present invention discloses a method for preparing a high-rate vanadium-doped negative electrode material, comprising the following steps:

[0016] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 24-48 hours, the reaction temperature is 100-200° C., and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0017] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination, the calcination time is 5-7 hours, the calcination temperature is 950-1150° C., and after natural cooling, iron niobium oxide is obtained;

[0018] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 300-400 r / min for 1-2 h. After ball milling, the ball milling product is evaporated to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 5-7 h, the calcination temperature is 950-1150° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0019] The following is a detailed description with reference to a number of embodiments.

[0020] Example 1

[0021] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 24 hours, the reaction temperature is 150° C., and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0022] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination at a temperature of 1000° C. for 6 hours, and naturally cooling to obtain iron niobium oxide;

[0023] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol being 1:20:80, and ball milling at a speed of 300 r / min for 1.5 h. After ball milling, rotary evaporation is performed to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 6 h, the calcination temperature is 1000° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0024] Example 2

[0025] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 48 hours, the reaction temperature is 180°C, and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0026] (2) placing the synthetic product obtained in step (1) in a box furnace for calcination, the calcination time is 5.5 hours, the calcination temperature is 1100° C., and after natural cooling, iron niobium oxide is obtained;

[0027] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol being 1:20:80, and ball milling at a speed of 400 r / min for 1.8 h. After ball milling, rotary evaporation is performed to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 6 h, the calcination temperature is 1000° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0028] Example 3

[0029] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 36 hours, the reaction temperature is 100° C., and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0030] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination, the calcination time is 5 hours, the calcination temperature is 1050° C., and after natural cooling, iron niobium oxide is obtained;

[0031] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 300 r / min for 2 h. After ball milling, rotary evaporation is performed to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 6 h, the calcination temperature is 950° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0032] Example 4

[0033] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 38 hours, the reaction temperature is 200°C, and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0034] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination at a temperature of 1000° C. for 7 hours, and naturally cooling to obtain iron niobium oxide;

[0035] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 400 r / min for 1 h. After ball milling, the ball milling product is evaporated to dryness by rotary evaporation to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 5 h, the calcination temperature is 950° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0036] Example 5

[0037] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 30 hours, the reaction temperature is 180°C, and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0038] (2) placing the synthetic product obtained in step (1) in a box furnace for calcination, the calcination time is 6 hours, the calcination temperature is 950° C., and after natural cooling, iron niobium oxide is obtained;

[0039] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 300 r / min for 1.5 h. After ball milling, rotary evaporation is performed to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 7 h, the calcination temperature is 1000° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

[0040] Example 6

[0041] (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 40 hours, the reaction temperature is 150° C., and then centrifugation washing is performed, and drying is performed to obtain a synthetic product; wherein the strong acid solution is composed of 15 ml of pure water and 1 ml of concentrated nitric acid, and the concentration of the concentrated nitric acid is 8 mol / L.

[0042] (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination, the calcination time is 6 hours, the calcination temperature is 1150° C., and after natural cooling, iron niobium oxide is obtained;

[0043] (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol being 1:20:80, and ball milling at a speed of 300 r / min for 1.5 h. After ball milling, rotary evaporation is performed to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination. The calcination time is 6 h and the calcination temperature is 1150° C. After natural cooling, a vanadium-doped negative electrode material is obtained.

[0044] Performance tests were performed on the above multiple embodiments, and the test results are shown in Table 1.

[0045]

[0046]

[0047] Table 1

[0048] It can be seen from the above test results that the negative electrode material prepared by the preparation method of the present invention can still maintain a relatively high gram capacity and capacity retention rate under high rate conditions, and the charge transfer resistance is very low, which is very suitable for high-power charging of new energy vehicles.

[0049] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-rate vanadium-doped negative electrode material, characterized in that: The following steps are included: (1) dissolving niobium oxalate in a strong acid solution to obtain an acidic niobium oxalate solution, then adding ammonium ferric citrate to the acidic niobium oxalate solution, stirring it fully to dissolve it, and obtaining a reaction solution, wherein the mass ratio of niobium oxalate to ammonium ferric citrate is 100:3, transferring the obtained reaction solution to a reactor for isothermal reaction, the reaction time is 24-48 hours, the reaction temperature is 100-200° C., and then centrifugally washing and drying to obtain a synthetic product; (2) placing the synthetic product obtained in step (1) in a box-type furnace for calcination, the calcination time is 5-7 hours, the calcination temperature is 950-1150° C., and after natural cooling, iron niobium oxide is obtained; (3) placing vanadium oxide and the iron niobium oxide obtained in step (2) into a ball mill, adding anhydrous ethanol, wherein the mass ratio of vanadium oxide, iron niobium oxide and anhydrous ethanol is 1:20:80, and ball milling is performed at a speed of 300-400 r / min for 1-2 h. After ball milling, the ball milling product is evaporated to dryness to obtain a ball milling product, and then the ball milling product is placed in a box furnace for calcination, the calcination time is 5-7 h, the calcination temperature is 950-1150° C., and after natural cooling, a vanadium-doped negative electrode material is obtained.

2. The method for preparing a high-rate vanadium-doped negative electrode material according to claim 1, characterized in that: The strong acid solution consists of 15 ml of pure water and 1 ml of concentrated nitric acid.

3. The method for preparing a high-rate vanadium-doped negative electrode material according to claim 2, characterized in that: The concentration of the concentrated nitric acid is 8 mol / L.

Images