WO2016202162A1

WO2016202162A1 - Method for synthesizing lithium-ion negative-electrode material li4ti5o12/c

Info

Publication number: WO2016202162A1
Application number: PCT/CN2016/083771
Authority: WO
Inventors: 田东
Original assignee: 田东
Priority date: 2015-06-16
Filing date: 2016-05-28
Publication date: 2016-12-22
Also published as: CN104993118A

Abstract

A method for synthesizing a lithium-ion negative-electrode material Li₄Ti₅O₁₂/C comprises the following steps: 1) mixing titanium dioxide and an organic carbon source by adding water, performing spray granulation after ball-milling treatment, and pre-treating the obtained powder in an inert atmosphere, to obtain carbon-coated titanium dioxide powder; 2) dissolving a lithium source in water, adding the titanium dioxide powder obtained in the step 1), and performing spray granulation after ball-milling treatment, to obtain dry powder; 3) treating the dry powder obtained in the step 2) in an inert atmosphere, and then performing high-temperature heat treatment and air classification, thus obtaining the lithium-ion negative-electrode material Li₄Ti₅O₁₂/C. Coating titanium dioxide with carbon first can prevent the agglomeration of lithium titanate during subsequent high-temperature treatment, and therefore can prevent the formation of excessively large lithium titanate grains, thereby effectively improving the diffusion rate of lithium ions during charging and discharging, improving the electrical conductivity of the material, and making full use of the electrical properties of lithium titanate.

Description

Method for synthesizing lithium ion anode material Li4Ti5O12/C

Technical field

The invention relates to a lithium ion battery anode material, in particular to a method for synthesizing a lithium ion anode material Li ₄ Ti ₅ O ₁₂ /C prepared by a carbon coating titanium dioxide process.

Background technique

At present, with the shortage of global petroleum resources and the deteriorating climate environment, the development of human society faces severe challenges. The development of clean and energy-efficient new energy vehicles has been highly valued by countries around the world. The development of new energy vehicles is the key to their power supply. Lithium-ion batteries have the advantages of high energy density, small self-discharge, no memory effect, wide operating voltage range, long service life and no environmental pollution. They are the main power source for new energy vehicles. The key electrode material of lithium ion battery is the final determinant of battery performance, and the negative electrode material plays an important role in improving the performance of lithium ion battery. Therefore, the development of high-performance, low-cost anode materials is of great significance to promote the development of new energy vehicles and related emerging industries.

The current anode material is mainly graphite, and its specific capacity is close to the theoretical value of 372 mAh/g. It is difficult to have room for improvement. Therefore, finding a high specific capacity anode material instead of carbon has become an important development direction. Li ₄ Ti ₅ O _{12 is} a new type of negative electrode material for lithium ion secondary batteries. Compared with other commercial materials, Li ₄ Ti ₅ O ₁₂ has the advantages of good cycle performance, no reaction with electrolyte, high safety performance, and stable charge and discharge platform. It is one of the most excellent anode materials for lithium-ion batteries that has received much attention in recent years. Compared with carbon negative electrode materials, lithium titanate has many advantages. Among them, the deintercalation of lithium ions in lithium titanate is reversible, and the crystal form of lithium ion in the process of inserting or extracting lithium titanate is not Changed, volume change is less than 1%, so it is called "zero strain material", which can avoid the structure damage caused by the back and forth expansion of the electrode material in the charge and discharge cycle, thereby improving the cycle performance and service life of the electrode, reducing the The number of cycles increases and the specific capacity is greatly attenuated, which has better cycle performance than the carbon negative electrode; however, since lithium titanate is an insulating material, its electrical conductivity is low, resulting in the rate performance in the application of lithium battery. The problem is poor. At the same time, the theoretical specific capacity of lithium titanate material is 175mAh/g, the actual specific capacity is more than 160mAh/g, and it has the disadvantages of low gram capacity. Therefore, it is necessary to modify lithium titanate.

Summary of the invention

The object of the present invention is to provide a method for synthesizing a lithium ion anode material Li ₄ Ti ₅ O ₁₂ /C prepared by a carbon-coated titanium dioxide process, which is simple in process route and suitable for large-scale industrial production.

The invention comprises the following steps:

1) mixing titanium dioxide and an organic carbon source with water, ball milling treatment, spray granulation, and the obtained powder is pretreated in an inert atmosphere to obtain carbon coated titanium dioxide powder;

2) dissolving the lithium source in water, adding the titanium dioxide powder obtained in the step 1), and then ball-milling and then spray granulating to obtain a dry powder;

3) The dry powder obtained in the step 2) is treated in an inert atmosphere, and then subjected to a high-temperature heat treatment, and the lithium ion negative electrode material Li ₄ Ti ₅ O ₁₂ /C is obtained by gas flow classification.

In the step 1), the titanium dioxide is one of anatase type titanium dioxide or a gold stone type titanium dioxide.

In the step 1), the organic carbon source may be one of water-soluble organic substances, and the water-soluble organic substance may be selected from the group consisting of glucose, sucrose, fructose, polyethylene glycol, polyacrylic acid, and shell polymerization. One of sugar and the like; the time of the ball milling treatment is 5 to 10 h; the temperature of the pretreatment is 400 to 500 ° C, and the pretreatment time is 5 to 8 h.

In the step 2), the lithium source may be one of a water-soluble lithium salt lithium acetate and lithium hydroxide; the ball milling treatment time is 2 to 3 hours.

In steps 1) and 2), the titanium dioxide and lithium sources are n(Li):n(Ti)=0.84-0.87 in terms of element moles; in step 1), the mass of the organic carbon source is titanium dioxide mass 10% to 15%; in steps 1) and 2), the water is used without brine, wherein the amount of water added in step 1) can be 3-4 times that of titanium dioxide by mass ratio, and step 2) The amount of addition is 3-4 times the mass of the carbon dioxide coated titanium dioxide powder by mass ratio.

In the steps 1) and 3), the inert atmosphere may be nitrogen gas or argon gas or the like.

In the step 3), the treatment temperature is 500 to 600 ° C, the treatment time is 10 to 20 h; the high temperature heat treatment temperature is 750 to 850 ° C, and the high temperature heat treatment time is 2 to 20 h.

Compared with the conventional method for synthesizing lithium ion negative electrode material Li ₄ Ti ₅ O ₁₂ , the invention has the advantages that carbon dioxide coating is first performed on the synthetic raw material titanium dioxide to avoid agglomeration of lithium titanate due to high temperature treatment in the later stage, and titanium is prevented. The production of lithium acid crystallites is too large, which can effectively increase the diffusion rate of lithium ions in charge and discharge over-symmetry. The organic carbon source soluble in water is used to make the carbon source more uniformly coated on the surface of the particle, and the nano-carbon coating layer with high conductivity after the organic substance is sintered and pyrolyzed greatly improves the conductivity of the material and ensures titanium. The performance of lithium acid battery performance.

detailed description

In order to make the technical means, the creative features, the workflow, and the method of use of the present invention easy to understand and understand, the present invention will be further described below in conjunction with specific embodiments.

Example 1

According to n(Li):n(Ti)=0.84, weigh 694g of lithium acetate and 1000g of titanium dioxide, add 100g of organic carbon source glucose according to the weight of titanium dioxide 10%, add titanium dioxide and glucose to add 3L of brine-free mixture, and grind it for 8h. After spray granulation, the obtained powder was pretreated at 500 ° C for 7 h in an inert atmosphere to obtain a carbon-coated titanium oxide powder. Lithium acetate was dissolved in 3.5 L of anhydrous saline, and carbon-coated titanium dioxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in a N ₂ atmosphere, and further heated to 800 ° C for 5 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 1.2%.

Example 2

According to n (Li): n (Ti) = 0.87, weigh 261 g of lithium hydroxide and 1000 g of titanium dioxide, add 150 g of organic carbon source sucrose according to the weight of titanium dioxide 15%, add titanium dioxide and sucrose to add 3.5 L of brine-free mixture, ball mill After 8 h of treatment, spray granulation, the obtained powder was pretreated at 500 ° C for 8 h in an inert atmosphere to obtain a carbon-coated titanium dioxide powder. Lithium hydroxide was dissolved in 3.5 L of anhydrous saline, and carbon-coated titanium dioxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 600 ° C for 8 h in a N ₂ atmosphere, and further heated to 800 ° C for 4 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 1.6%.

Example 3

According to n (Li): n (Ti) = 0.85, weigh 255g of lithium hydroxide and 1000g of titanium dioxide, add 100g of organic carbon source polyethylene glycol according to 10% by weight of titanium dioxide, add titanium dioxide and polyethylene glycol to add 3.0L The mixture was uniformly mixed without brine, ball milled for 3 hours, spray granulated, and the obtained powder was pretreated at 500 ° C for 8 hours in an inert atmosphere to obtain a carbon-coated titanium dioxide powder. Lithium hydroxide was dissolved in 3.5 L of anhydrous saline, and carbon-coated titanium dioxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in a N ₂ atmosphere, and further heated to 820 ° C for 6 h, cooled, sieved, and classified by air flow to obtain a product.

The resulting product had a carbon content of 2.3%.

Example 4

According to n (Li): n (Ti) = 0.86, weigh 710g of lithium acetate and 1000g of titanium dioxide, add 150g of organic carbon source polyacrylic acid according to the weight of titanium dioxide 15%, add titanium dioxide and polypropylene to add 3.6L of brine-free mixing, After ball milling for 8 h, spray granulation, the obtained powder was pretreated at 500 ° C for 8 h in an inert atmosphere to obtain a carbon-coated titanium dioxide powder. Lithium acetate was dissolved in 3.5 L of anhydrous saline, and carbon-coated titanium dioxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in a N ₂ atmosphere, heated to 880 ° C for 8 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product had a carbon content of 2.6%.

Example 5

According to n (Li): n (Ti) = 0.87, weigh 261 g of lithium hydroxide and 1000 g of titanium dioxide, add 100 g of organic carbon source glucose according to 10% by weight of titanium dioxide, add titanium dioxide and glucose to add 3.6 L of brine-free mixture, ball mill After 8 h of treatment, spray granulation, the obtained powder was pretreated at 500 ° C for 8 h in an inert atmosphere to obtain a carbon-coated titanium dioxide powder. Lithium hydroxide was dissolved in 4.0 L of anhydrous saline, and carbon-coated titanium dioxide powder was added thereto to be uniformly stirred, ball-milled for 3 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in a N ₂ atmosphere, and further heated to 880 ° C for 5 h, cooled, sieved, and classified by air flow to obtain a product.

The resulting product had a carbon content of 2.3%.

Comparative example 1

According to n(Li):n(Ti)=0.84, 694 g of lithium acetate and 1000 g of titanium dioxide were weighed, added with 3 L of brine-free mixture, and ball-milled for 8 hours, and spray-granulated to obtain a dry powder. The powder was placed in a rotary kiln, sintered at 650 ° C for 8 h in a N ₂ atmosphere, and further heated to 800 ° C for 5 h, cooled, sieved, and classified by gas flow to obtain a product.

The resulting product has a carbon content of zero.

Electrochemical performance test

In order to test the performance of the lithium titanate negative electrode material of the modified lithium ion battery prepared by the method of the present invention, the half cell test method was used for testing, and the anode materials of the above examples and comparative examples were used: acetylene black: PVDF (polyvinylidene fluoride) = 93:3:4 (weight ratio), adding appropriate amount of NMP (N-methylpyrrolidone) to make a slurry, coating on copper foil, drying at 110 ° C for 8 hours under vacuum to make a negative electrode sheet; The electrode and the electrolyte were 1 mol/L LiPF6/EC+DEC+DMC=1:1:1, and the polypropylene microporous membrane was a separator, which was assembled into a battery. The charge-discharge voltage is 1.0-2.5V, and the charge-discharge rate is 0.5C. The battery performance can be tested. The test results are shown in Table 1.

Table 1 compares the performance of negative electrode materials in different examples and comparative examples.

The basic principles and main features of the present invention and the advantages of the present invention are shown and described above, and those skilled in the art should understand that the present invention is not limited by the above embodiments, and that the above embodiments and descriptions are merely illustrative of the present invention. The present invention is subject to various modifications and improvements without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The requirements and their equivalents are defined.

Claims

A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C, which comprises the following steps:

1) mixing titanium dioxide and an organic carbon source with water, ball milling treatment, spray granulation, and the obtained powder is pretreated in an inert atmosphere to obtain carbon coated titanium dioxide powder;

2) dissolving the lithium source in water, adding the titanium dioxide powder obtained in the step 1), and then ball-milling and then spray granulating to obtain a dry powder;

3) The dry powder obtained in the step 2) is treated in an inert atmosphere, and then subjected to a high-temperature heat treatment, and the lithium ion negative electrode material Li 4 Ti 5 O 12 /C is obtained by gas flow classification.
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 1), the titanium dioxide is one of an anatase type titanium dioxide or a gold stone type titanium dioxide. .
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 1), the organic carbon source is one of water-soluble organic substances. The water-soluble organic substance is selected from the group consisting of glucose, sucrose, fructose, polyethylene glycol, polyacrylic acid, and chitosan.
The method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 1), the time of the ball milling treatment is 5 to 10 h; the temperature of the pretreatment The temperature is 400 to 500 ° C, and the pretreatment time is 5 to 8 hours.
The method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 2), the lithium source is a lithium hydroxide lithium hydroxide or lithium hydroxide. One type; the ball milling treatment time is 2 to 3 hours.
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the steps 1) and 2), the titanium dioxide and the lithium source are n (Li) in terms of element moles ): n (Ti) = 0.84 to 0.87.
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 1), in the step 1), the mass of the organic carbon source is titanium dioxide mass 10% to 15%.
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in steps 1) and 2), in steps 1) and 2), the water is used without The brine, wherein the amount of water added in the step 1) is 3 to 4 times the mass ratio of the titanium dioxide, and the amount of water in the step 2) is 3 to 4 times the mass of the carbon dioxide coated titanium dioxide powder.
A method of synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the steps 1) and 3), the inert atmosphere is nitrogen or argon.
A method for synthesizing a lithium ion negative electrode material Li 4 Ti 5 O 12 /C according to claim 1, wherein in the step 3), the temperature of the treatment is 500 to 600 ° C, and the treatment time is 10 to 20h; the temperature of the high temperature heat treatment is 750-850 ° C, and the heat treatment time is 2-20 h.