CN104733698B - A kind of method preparing Vanadium sesquioxide cladding lithium titanate anode material - Google Patents

Abstract

The invention relates to the technical field of manufacturing lithium ion batteries, in particular to a method for preparing a vanadium trioxide-coated lithium titanate negative electrode material. Dissolve lithium acetate and polyvinylpyrrolidone PVP in 500 mL of distilled water, add nano-titanium dioxide, stir magnetically for 1 hour to obtain a slurry, and spray dry to obtain a lithium titanate precursor; the precursor is heat-treated in an air atmosphere until the reaction is complete to obtain pure titanic acid Lithium anode material: dissolving ammonium metavanadate and glycine in distilled water, adding pure lithium titanate anode material, magnetically stirring for 1 hour, evaporating the solvent, and vacuum drying to obtain a vanadium trioxide-coated lithium titanate precursor; the precursor The body is heat-treated in an argon atmosphere until the reaction is completed, and the target product is vanadium trioxide-coated lithium titanate negative electrode material.

Description

A method for preparing vanadium trioxide-coated lithium titanate negative electrode material

technical field

The invention relates to the technical field of manufacturing lithium ion batteries, in particular to a method for preparing a vanadium trioxide-coated lithium titanate negative electrode material.

Background technique

Commercialized lithium-ion battery anode materials mostly use various lithium-intercalated carbon materials. The disadvantages are: react with the electrolyte to form a surface passivation film, resulting in electrolyte consumption and low initial Coulombic efficiency; lithium dendrites are precipitated, making the battery A short circuit can pose a serious safety hazard. Spinel-type lithium titanate (Li ₄ Ti ₅ O ₁₂ ) has obvious advantages as a new type of lithium-ion battery anode material: zero strain, excellent cycle performance; high redox potential (1.5VvsLi), not with Commonly used electrolyte reacts, good safety; environment friendly, easy to prepare, low cost and so on. However, the low conductivity of Li ₄ Ti ₅ O ₁₂ leads to poor high-rate performance, which greatly restricts its promotion and application, especially in the field of power batteries, which is attracting worldwide attention. The high-rate working characteristics of the material determine its performance. Therefore, improving the high-rate performance of Li ₄ Ti ₅ O ₁₂ has become one of the core topics that researchers are focusing on. In-depth research on this type of material and actively promoting its industrialization is the key to solving the problem of long-life and safe lithium-ion batteries for electric vehicles. The rapid industrialization of this type of material not only has great economic benefits, but also has abyss. It is beneficial to the sustainable development of our country and even the global economy.

Contents of the invention

In order to improve the poor electronic conductivity of Li ₄ Ti ₅ O ₁₂ , the present invention proposes a method for preparing vanadium trioxide-coated lithium titanate negative electrode material, so as to improve its specific capacity under high rate conditions.

Technical scheme of the present invention:

1) Stirring and mixing: Weigh a certain amount of lithium acetate and polyvinylpyrrolidone (PVP), dissolve them in 500 mL of distilled water; add a certain amount of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry.

2) Spray drying: the slurry in step 1) was spray-dried at 110° C. to obtain a lithium titanate precursor.

3) High-temperature cracking: heat-treat the lithium titanate precursor in step 2) in an air atmosphere until the reaction is complete to obtain a pure lithium titanate negative electrode material; wherein, the heat treatment is calcined at 750° C. for 8 hours.

4) Preparation of vanadium trioxide-coated lithium titanate precursor: weigh a certain amount of ammonium metavanadate and glycine, dissolve in 500 mL of distilled water; add the pure lithium titanate negative electrode material described in step 3), and stir magnetically for 1 h; After evaporating the solvent at 100° C., vacuum drying at 80° C. for 1 h to obtain a vanadium trioxide-coated lithium titanate precursor.

5) High-temperature treatment: heat-treat the vanadium trioxide-coated lithium titanate precursor described in step 4) in an argon atmosphere until the reaction is completed, and obtain the target product vanadium trioxide-coated lithium titanate negative electrode material; wherein, the The above heat treatment is firing at 600°C for 6h.

The beneficial effects of the present invention are:

Coating vanadium trioxide on the surface of lithium titanate improves the electronic conductivity of Li ₄ Ti ₅ O ₁₂ , thereby achieving the purpose of obtaining the composite material with high rate performance.

The vanadium trioxide-coated lithium titanate negative electrode material prepared by the invention has a pure phase, uniform grain distribution, high rate performance and good cycle performance. When the coating amount of vanadium trioxide is 2%, the discharge capacities at 0.2C and 10C are 173mAhg ^-1 and 154mAhg ^-1 respectively; after 200 cycles at 10C, the discharge capacity remains at 96.8%.

Description of drawings

Fig. 1 is the X-ray diffraction figure of embodiment 1, embodiment 2, embodiment 3 and embodiment 4 samples. In Fig. 1, the abscissa is 2θ/°, and θ is the diffraction angle.

Fig. 2 is the transmission electron micrograph of embodiment 3.

Fig. 3 is the cycle performance of the samples of Example 1, Example 2, Example 3 and Example 4 at different magnifications. In Figure 3, the abscissa is the number of cycles, the ordinate is the specific capacity/mAhg ^-1 , and the charge and discharge rates are 0.2C (corresponding to 0-10 cycles), 0.5C (corresponding to the cycle number of 11-20 times), 1C (the corresponding number of cycles is 21-30 times), 2C (the corresponding number of cycles is 31-40 times), 5C (the corresponding number of cycles is 41-50 times), 10C ( The corresponding number of cycles is 51-60 times).

Figure 4 is the cycle performance of the negative electrode material of Example 3 at 10C. In Fig. 4, the abscissa is the number of cycles, and the ordinate is the specific capacity/mAhg ^-1 .

detailed description

The method for preparing vanadium trioxide-coated lithium titanate negative electrode material in the present invention is specifically implemented according to the following steps:

1) Stirring and mixing: Weigh a certain amount of lithium acetate and polyvinylpyrrolidone PVP (molecular weight 40000 (avg)), dissolve in 500 mL of distilled water; add a certain amount of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry.

2) Spray drying: the slurry in step 1) was spray-dried at 110° C. to obtain a lithium titanate precursor.

3) High-temperature cracking: heat-treat the lithium titanate precursor in step 2) in an air atmosphere until the reaction is complete to obtain a pure lithium titanate negative electrode material; wherein, the heat treatment is calcined at 750° C. for 8 hours.

4) Preparation of vanadium trioxide-coated lithium titanate precursor: weigh a certain amount of ammonium metavanadate and glycine, dissolve in 500 mL of distilled water; add the pure lithium titanate negative electrode material described in step 3), and stir magnetically for 1 h; After evaporating the solvent at 100° C., vacuum drying at 80° C. for 1 h to obtain a vanadium trioxide-coated lithium titanate precursor.

5) High-temperature treatment: heat-treat the vanadium trioxide-coated lithium titanate precursor described in step 4) in an argon atmosphere until the reaction is completed, and obtain the target product vanadium trioxide-coated lithium titanate negative electrode material; wherein, the The above heat treatment is firing at 600°C for 6h.

Example 1

Preparation of Li ₄ Ti ₅ O ₁₂ Anode Material

Weigh 0.06mol of lithium acetate and 1.5g of polyvinylpyrrolidone (PVP), dissolve them in 500mL of distilled water; add 0.075mol of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry; spray dry the slurry at 110°C to obtain a lithium titanate precursor ; The lithium titanate precursor was calcined at 750° C. for 8 hours in an air atmosphere to obtain a pure lithium titanate negative electrode material. The X-ray diffraction pattern is shown in Figure 1.

Example 2

Preparation of Li ₄ Ti ₅ O ₁₂ Anode Material Coated with 1% Vanadium Trioxide

Weigh 0.06mol of lithium acetate and 1.5g of polyvinylpyrrolidone (PVP), dissolve them in 500mL of distilled water; add 0.075mol of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry; spray dry the slurry at 110°C to obtain a lithium titanate precursor ; The lithium titanate precursor was roasted at 750°C for 8 hours in an air atmosphere to obtain a pure lithium titanate negative electrode material; weighed 0.109g ammonium metavanadate and 0.01mol glycine, dissolved in 500mL distilled water; added pure lithium titanate negative electrode Materials, magnetically stirred for 1h; after evaporating the solvent at 100°C, vacuum drying at 80°C for 1h to obtain the vanadium trioxide-coated lithium titanate precursor; the vanadium trioxide-coated lithium titanate precursor was Calcining at 600° C. for 6 h to obtain a negative electrode material of vanadium trioxide-coated lithium titanate. The X-ray diffraction pattern is shown in Figure 1.

Example 3

Preparation of Li ₄ Ti ₅ O ₁₂ Anode Material Coated with 2% Vanadium Trioxide

Weigh 0.06mol of lithium acetate and 1.5g of polyvinylpyrrolidone (PVP), dissolve them in 500mL of distilled water; add 0.075mol of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry; spray dry the slurry at 110°C to obtain a lithium titanate precursor ; The lithium titanate precursor was roasted at 750°C for 8 hours in an air atmosphere to obtain a pure lithium titanate negative electrode material; weighed 0.220g ammonium metavanadate and 0.01mol glycine, dissolved in 500mL distilled water; added pure lithium titanate negative electrode Materials, magnetically stirred for 1h; after evaporating the solvent at 100°C, vacuum drying at 80°C for 1h to obtain the vanadium trioxide-coated lithium titanate precursor; the vanadium trioxide-coated lithium titanate precursor was Calcining at 600° C. for 6 h to obtain a negative electrode material of vanadium trioxide-coated lithium titanate. See Figure 1 for the X-ray diffraction diagram, and Figure 2 for the transmission electron microscope diagram.

Example 4

Preparation of Li ₄ Ti ₅ O ₁₂ Anode Material Coated with 3% Vanadium Trioxide

Weigh 0.06mol of lithium acetate and 1.5g of polyvinylpyrrolidone (PVP), dissolve them in 500mL of distilled water; add 0.075mol of nano-titanium dioxide, and stir magnetically for 1 hour to obtain a slurry; spray dry the slurry at 110°C to obtain a lithium titanate precursor ; The lithium titanate precursor was roasted at 750°C for 8 hours in an air atmosphere to obtain a pure lithium titanate negative electrode material; weighed 0.333g ammonium metavanadate and 0.01mol glycine, dissolved in 500mL distilled water; added pure lithium titanate negative electrode Materials, magnetically stirred for 1h; after evaporating the solvent at 100°C, vacuum drying at 80°C for 1h to obtain the vanadium trioxide-coated lithium titanate precursor; the vanadium trioxide-coated lithium titanate precursor was Calcining at 600° C. for 6 h to obtain a negative electrode material of vanadium trioxide-coated lithium titanate. The X-ray diffraction pattern is shown in Figure 1.

The diffraction peaks of the samples obtained in Example 1, Example 2, Example 3 and Example 4 in Figure 1 are consistent with those reported in the literature, indicating that the coating of vanadium trioxide will not affect the Li ₄ Ti ₅ O ₁₂ phase.

It can be seen from FIG. 2 that in the sample obtained in Example 3, the surface of lithium titanate is coated with vanadium trioxide with a thickness of 4 nm.

The composite negative electrode material prepared by the invention can be used to prepare negative electrodes for lithium ion batteries by using a slurry coating method. The specific operation is to mix the active ingredient (Li ₄ Ti ₅ O ₁₂ ), the conductive agent Super-Pcarbon, and the binder LA132 in a mass ratio of 85:10:5, and then evenly coat it on the aluminum foil, and dry it under vacuum at 100°C Obtain the negative electrode sheet.

Electrochemical performance test:

The material prepared in the above examples is used as the active ingredient to make the negative electrode (the preparation method of the negative electrode is as above), metal lithium is used as the positive electrode, Celgard2400 is used as the diaphragm, and EC/DEC/DMC of 1mol/LLiPF ₆ (volume ratio is 1:1:1) The solution is an electrolyte. Assemble it into a CR2032 button battery, and conduct a constant current charge and discharge performance test on the battery test system. The charging voltage range is 1-3V. Cycle performance diagrams are shown in Figures 3 and 4.

Figure 3 shows the cycle performance of the samples prepared according to Example 1, Example 2, Example 3 and Example 4 at 0.2C, 0.5C, 1C, 2C, 5C, and 10C. It can be seen from Figure 3 that as the coating amount of vanadium trioxide increases, the discharge capacity of Li ₄ Ti ₅ O ₁₂ at various charge and discharge rates first increases and then decreases, and the coating amount of vanadium trioxide is 2 % has the best electrochemical performance, and the discharge capacities of Li ₄ Ti ₅ O ₁₂ /C at 0.2C and 10C are 173mAh/g and 154mAh/g, respectively.

Fig. 4 is the circulation of the sample prepared in Example 3 at 10C. It can be seen that after 100 cycles, the discharge capacity remains at 96.8%, indicating that the vanadium trioxide-coated lithium titanate has good cycle performance at 10C.

Claims (6)

1. a kind of prepare Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：The concrete step of methods described Suddenly it is,

1) stirring mixing

Quilonorm (SKB) and Polyvinylpyrrolidone PVP are dissolved in 500mL distilled water, add nano titanium oxide, magnetic agitation 1h Obtain slurry；

2) it is spray-dried

By step 1) gained slurry spraying be dried to obtain lithium titanate precursor；

3) Pintsch process

By step 2) gained lithium titanate precursor is heat-treated to reaction in air atmosphere and completes, and obtains pure lithium titanate anode material；

4) Vanadium sesquioxide cladding lithium titanate precursor preparation

Ammonium metavanadate and glycine are dissolved in 500mL distilled water, add step 3) the pure lithium titanate anode material of gained, magnetic force stirs Mix 1h, vacuum drying after solvent evaporated obtains Vanadium sesquioxide cladding lithium titanate precursor；

5) high-temperature process

By step 4) gained Vanadium sesquioxide cladding lithium titanate precursor is heat-treated to reaction in argon gas atmosphere and completes, and obtains target Product Vanadium sesquioxide coats lithium titanate anode material.

2. prepare as claimed in claim 1 Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：Step 2) be spray-dried described in is to be spray-dried at 110 DEG C.

3. prepare as claimed in claim 1 Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：Step 3) heat treatment described in is roasting 8h at 750 DEG C.

4. prepare as claimed in claim 1 Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：Step 4) solvent evaporated described in is solvent evaporated at 100 DEG C.

5. prepare as claimed in claim 1 Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：Step 4) vacuum drying described in is vacuum dried 1h at being 80 DEG C.

6. prepare as claimed in claim 1 Vanadium sesquioxide coat lithium titanate anode material method it is characterised in that：Step 5) heat treatment described in is roasting 6h at 600 DEG C.