CN102442695A - Preparation method of lithium titanate material of lithium ion battery - Google Patents

Abstract

The present invention discloses a method for preparing lithium titanate material for lithium ion batteries, which comprises the following steps: A: mixing lithium salt and titanium dioxide at a molar ratio of 0.84, adding a dispersant, grinding and mixing, and then vacuum drying to obtain a precursor; B: heating the obtained precursor to 800-950°C at a heating rate of 1-10°C/min under nitrogen or air conditions and reacting for 12-24h; C: cooling the sintered product, adding additives thereto, grinding and mixing, and then heating to 400-600°C at a heating rate of 1-10°C/min under nitrogen or air conditions and keeping the temperature for 2-10h, and then crushing after cooling to obtain lithium titanate negative electrode material for lithium ion batteries. The lithium titanate prepared by the above preparation method has a uniform particle size distribution, greatly improves the electronic conductivity of the material, and effectively improves the rate charge and discharge performance and cycle stability of the material.

Description

A kind of preparation method of lithium titanate material of lithium ion battery

technical field

The invention relates to a preparation method of a lithium titanate material for a lithium battery, and belongs to the technical field of preparation of lithium secondary battery materials. the

Background technique

Spinel-type lithium titanate (Li ₄ Ti ₅ O ₁₂ ) has a voltage of 1.55V, and has obvious advantages as a negative electrode material for lithium-ion batteries: lithium titanate is a zero-strain material, and the material is The volume change of lithium titanate is very small; the stability of the crystal structure improves the cycle performance and service life of the electrode; it reduces the specific capacity attenuation caused by the increase of the number of cycles; the high chemical diffusion coefficient of lithium titanate makes the negative electrode material can be Fast, multi-cycle charge and discharge. Commonly used pure lithium titanate materials have low conductivity and poor high-rate performance, so the materials need to be modified.

Lithium titanate-related patents include: Publication No. CN1978524A Preparation method of lithium titanate/polyacene compound for fast charging battery material, the preparation method is to combine lithium source, titanium precursor, self-made polyacene or synthetic Phenolic resin, lithium titanate composite material obtained by high-temperature heat treatment, the specific capacity of the first discharge at 0.3C rate is 155-162mAh/g, and the specific capacity of the first discharge at 9C rate is 95-110mAh/g. Publication No. CN101402469A uses a one-step solid phase method to synthesize lithium titanate with a spinel structure, and reacts at a temperature range of 700-1300° C. for 4-36 hours to obtain lithium titanate with a cycle specific capacity of 100-160mAh/g. The patent publication number is CN101456581A. Using titanium dioxide, lithium salts, and rare earth oxides as raw materials, lithium titanate, a negative electrode material for lithium batteries, is synthesized by a high-temperature solid-state method. The specific capacity at 0.2C is as high as 173mAh/g for the first time, and the cycle performance is excellent. the

Contents of the invention

The purpose of the present invention is to provide a preparation method of a lithium titanate material for a lithium ion battery that can improve the electronic conductivity of the lithium titanate material, improve the rate charge and discharge performance and cycle stability of the lithium titanate material. the

Its technical solution is: a preparation method of lithium titanate material for lithium ion battery, characterized in that it comprises the following steps:

A: Mix lithium salt and titanium dioxide at a molar ratio of 0.84, add a dispersant to grind and mix, and then dry in vacuum to obtain a precursor;

B: The prepared precursor is heated up to 800-950°C under nitrogen or air at a heating rate of 1-10°C/min and reacted for 12-24 hours;

C: After cooling the sintered product, add additives to it for grinding and mixing, then raise the temperature to 400-600°C under nitrogen or air at a heating rate of 1-10°C/min and keep it warm for 2-10h, and powder after cooling Lithium titanate negative electrode material for lithium ion battery. the

Its technical effect is: the present invention improves its electrical conductivity by adding additives to modify the lithium titanate material during the sintering process, so the particle size distribution of the prepared lithium titanate is uniform, greatly improving the electronic conductivity of the material, effectively improving The rate charge-discharge performance and cycle stability of the material were improved. After testing: the charge and discharge capacity reaches 173.5mAh/g at 0.5C rate, 162.6mAh/g at 1C, and 131.5mAh/g at 10C, and the capacity retention rate is above 98% after 100 cycles at each rate . Compared with pure lithium titanate, the modified lithium titanate has higher capacity, better cycle stability and longer service life under high current; and its process is simple, suitable for industrial production. the

Description of drawings

Fig. 1 is the X-ray diffraction spectrum of the lithium titanate prepared in embodiment 1;

Fig. 2 is the SEM figure of the lithium titanate prepared in embodiment 1;

Fig. 3 is the first charge-discharge curve under each rate of lithium titanate prepared in embodiment 1;

FIG. 4 is a rate performance diagram of lithium titanate prepared in Example 1. FIG. the

Detailed ways

Example 1. the

Take 200g Li ₂ CO ₃ and 500g anatase TiO ₂ , add absolute ethanol as a dispersant, grind and mix, and then vacuum dry to obtain a precursor;

The prepared precursor was heated to 900°C under nitrogen at a heating rate of 5°C/min and reacted for 20h;

After cooling the sintered product, add aluminum nitrate to it, grind and mix, then raise the temperature to 500°C under nitrogen at a rate of 5°C/min and keep it warm for 10 hours, and then pulverize it to obtain lithium titanate negative electrode of lithium ion battery Material. the

The lithium titanate sample obtained above is analyzed by X-ray diffraction to obtain the XRD spectrum of lithium titanate as shown in Figure 1, as can be seen from the figure, the XRD pattern of the sample is basically the same as the lithium titanate standard sample , without the appearance of impurity peaks. the

It can be seen from the SEM electron microscope photo in Figure 2 that the distribution of lithium titanate material is relatively uniform without obvious agglomeration phenomenon, the average particle size is about 2.0 μm, and its porous morphology is conducive to the circulation of the material. the

The lithium titanate sample prepared above, acetylene black, and polyvinylidene fluoride (PVDF) were uniformly mixed in a mass ratio of 90:5:5, rolled to form a film, dried in vacuum at 80°C for 10 hours, assembled into a half-cell, electrolyzed The liquid is LiPF ₆ (EC:DEC=1:1). Using the Land battery test system, the test voltage is 1.0-2.5V, as shown in Figure 3, the first discharge capacity at 0.5C rate reaches 173.5mAh/g, the first discharge capacity at 1C reaches 162.6mAh/g, and the first discharge capacity at 10C is 131.5mAh/g, it can be seen that when the lithium titanate prepared in this example is used as the negative electrode material of the lithium ion battery, its charge-discharge specific capacity is high, and the high-rate discharge performance is superior.

As can be seen from the rate performance diagram of the lithium titanate prepared in this example as shown in Figure 4: when the lithium titanate prepared in this example is used as a negative electrode material for a lithium ion battery, at different rates, 20 times After cycling, the capacity retention rate is above 98%. the

Example 2. the

Weigh 129.5g LiOH, 500g anatase TiO ₂ , add acetone as a dispersant, mix and mill in a ball mill for 5 hours, and then vacuum dry to obtain a precursor; Raise the temperature to 950°C under the air and react for 12 hours; after the sintered product is cooled, add 6.2g of manganese nitrate to it, grind and mix, then raise the temperature to 600°C under the air at a heating rate of 8°C/min and keep it warm for 5 hours. After cooling, it is pulverized to obtain a lithium titanate negative electrode material for a lithium ion battery.

Referring to Example 1, the battery was assembled and tested in the same manner. The lithium titanate prepared in this example had an initial discharge capacity of 170mAh/g at a rate of 0.5C, and a capacity retention rate of 98.3% after 20 cycles. the

Example 3. the

Weigh 372.7g LiNO ₃ , 500g anatase TiO ₂ and water into a ball mill, mix and ball mill for 6 hours, then vacuum-dry to obtain a precursor; heat up the prepared precursor in air at a heating rate of 1°C/min to 800°C and react for 20 hours; after the sintered product is cooled, add 26.1g of chromium acetate to it, grind and mix, then raise the temperature to 450°C in the air at a heating rate of 1°C/min and keep it warm for 8 hours, and then pulverize it after cooling The lithium titanate negative electrode material of the lithium ion battery is obtained.

Referring to Example 1, the battery was assembled and tested in the same manner. The lithium titanate prepared in this example had an initial discharge capacity of 171.2mAh/g at a rate of 0.5C, and a capacity retention rate of 98.6% after 20 cycles. the

Example 4:

Weigh 200g Li ₂ CO ₃ , 500g anatase TiO ₂ and acetone (dispersant) into a ball mill for mixing and ball milling for 5 hours, then vacuum dry to obtain a precursor; heat the prepared precursor at a rate of 5°C/min , heated to 800°C under nitrogen and reacted for 24 hours; after the sintered product was cooled, 21g of zirconia was added to it, ground and mixed, and then heated to 600°C under nitrogen at a heating rate of 5°C/min and kept for 6 hours , and after cooling, the lithium titanate negative electrode material of the lithium ion battery can be obtained by pulverizing.

Referring to Example 1, the same method was used to assemble and test the battery. The lithium titanate prepared in this example had an initial discharge capacity of 174.7mAh/g at a rate of 0.5C, and a capacity retention rate of 99.1% after 20 cycles. the

Example 5. the

Weigh 129.5g LiOH and 500g anatase TiO ₂ , use absolute ethanol as a dispersant, put them into a ball mill for mixing and ball milling for 6 hours, and then vacuum dry to obtain a precursor; heat the prepared precursor at a rate of 2°C/min rate, heated to 950°C under air and reacted for 20h; after the sintered product was cooled, 31.5g of molybdenum chloride was added to it, ground and mixed, and then heated to 550°C under air at a rate of 2°C/min. Keep it warm for 6 hours, and then pulverize it after cooling to obtain lithium titanate negative electrode material for lithium ion battery.

Example 6. the

Weigh 200g Li ₂ CO ₃ , 500g anatase TiO ₂ , use acetone as a dispersant, put them into a ball mill for mixing and ball milling for 6 hours, and vacuum dry to obtain a precursor; the prepared precursor is heated at a rate of 8°C/min , heated to 850°C under air and reacted for 15h; after the sintered product was cooled, 7g of zinc chloride was added to it, ground and mixed, and then heated to 500°C under air at a heating rate of 8°C/min and kept for 6h , and after cooling, the lithium titanate negative electrode material of the lithium ion battery can be obtained by pulverizing.

Referring to Example 1, the battery was assembled and tested in the same manner. The lithium titanate prepared in this example had an initial discharge capacity of 170.6mAh/g at a rate of 0.5C, and a capacity retention rate of 98.5% after 20 cycles. the

Claims (4)

1. the preparation method of a lithium ion battery lithium titanate material is characterized in that comprising the steps:

A: lithium salts and titanium oxide are pressed 0.84 mixed in molar ratio, add the dispersion agent ground and mixed, vacuum-drying then obtains presoma;

B:, under nitrogen or air conditions, be warming up to 800～950 ℃ and react 12～24h with the temperature rise rate of the presoma that makes by 1～10 ℃/min;

C: after the cooling of the product behind the sintering; Add the additive ground and mixed therein; Again with the temperature rise rate of 1～10 ℃/min, under nitrogen or air conditions, be warming up to 400～600 ℃ and be incubated 2～10h, cooling back powder essence promptly gets lithium titanate anode material for lithium ion battery.

2. the preparation method of lithium ion battery lithium titanate material according to claim 1 is characterized in that: said lithium salts is one or more in Quilonum Retard, Lithium Hydroxide MonoHydrate, Lithium Oxide 98min, lithium nitrate or the lithium oxalate.

3. the preparation method of lithium ion battery lithium titanate material according to claim 1 is characterized in that: described dispersion agent is a kind of in absolute ethyl alcohol, water or the acetone.

4. the preparation method of lithium ion battery lithium titanate material according to claim 1; It is characterized in that: the said additive that in step C, adds is a kind of in nitrate salt, muriate, oxide compound, carbonate, oxalate or the acetate compound, and add-on is the 0.1-5% of lithium salts and titanium oxide mole number.

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