WO2017024719A1

WO2017024719A1 - Preparation method for high capacity lithium-ion battery negative electrode material

Info

Publication number: WO2017024719A1
Application number: PCT/CN2015/098490
Authority: WO
Inventors: 田东
Original assignee: 田东
Priority date: 2015-08-07
Filing date: 2015-12-23
Publication date: 2017-02-16
Also published as: CN105140481A

Abstract

Disclosed is a preparation method for a high capacity lithium-ion battery negative electrode material. The preparation method for the high capacity lithium-ion battery negative electrode material, in which raw materials are proportioned according to parts by weight, comprises the following process steps: (1) titanium dioxide, lithium carbonate, tin nanoparticles, and a resin are mixed into a uniform slurry; (2) a precursor powder is produced via spray drying; and, (3) under the protection of a noble gas, the powder produced in step (2) undergoes a high temperature treatment and is then cooled and sieved to produce the high capacity lithium-ion battery negative electrode material.

Description

Method for preparing high-capacity lithium battery anode material

Technical field

The invention relates to a preparation method of a lithium ion battery anode material, in particular to a preparation method of a lithium ion battery lithium titanate anode material.

Background technique

Lithium-ion batteries, which have been widely used in electronic products such as mobile phones and notebook computers, have large specific energy, high specific power, low self-discharge, good cycle characteristics, fast charging and high efficiency, wide operating temperature range, and no environmental pollution. Advantages, the lithium-ion batteries currently used in the market basically use carbon materials as the negative electrode, but the carbon material is the negative electrode in the practical application, there are some insurmountable weaknesses, for example, reacting with the electrolyte during the first discharge to form a surface. The passivation film causes the electrolyte to be consumed and the first coulombic efficiency is low; the potential of the carbon electrode is very close to the potential of the metal lithium. When the battery is overcharged, the surface of the carbon electrode is liable to precipitate metallic lithium, which may cause a short circuit, thereby causing a short circuit. The battery exploded. In order to solve the safety problem of lithium batteries, a lot of research has been done. As a new type of lithium ion secondary battery anode material, spinel Li4Ti5O12 has the advantages of good cycle performance, no reaction with electrolyte, high safety performance, stable charge and discharge platform, etc., compared with other commercial materials. One of the most excellent lithium ion battery anode materials 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. Metal tin has the advantages of high lithium storage capacity (994 mAh/g) and low lithium ion deintercalation platform voltage, and is a non-carbon negative electrode material with great development potential. In recent years, extensive research has been carried out on such materials and some progress has been made. However, in the process of reversible lithium storage, the volume expansion of metallic tin is remarkable, resulting in poor cycle performance and rapid decay of capacity, so it is difficult to meet the requirements of large-scale production. For this reason, by introducing a non-metallic element such as carbon, the metal tin is stabilized by alloying or compounding, and the volume expansion of tin is slowed down. Carbon can prevent direct contact between tin particles, inhibit the agglomeration and growth of tin particles, and act as a buffer layer.

Summary of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a high-capacity lithium battery anode material to solve the problems raised in the above background art.

In order to achieve the above object, the present invention is implemented by the following technical solutions:

A method for preparing a high-capacity lithium battery anode material, the raw material according to the proportion by weight, comprising the following process steps:

(1) Preparation of precursor slurry: According to the ratio of titanium dioxide: lithium carbonate: nano tin: resin = 100: 38 to 40: 3 to 5: 5 to 10, each component is weighed and dispersed in an organic solvent ethanol to adjust the solid. The content is 20% to 40%, and hexamethylenetetramine with a resin content of 3% to 5% is simultaneously added, and then continuously stirred to obtain a precursor slurry;

(2) atomization, drying, granulation and classification: the precursor slurry prepared in the step (1) is subjected to atomization, drying and granulation, and then subjected to powder classification to obtain an average particle diameter of 5 to 15 μm. Powder

(3) Heat treatment: the powder obtained in the step (2) is heated to a temperature of 800 to 1000 ° C at a rate of 1 to 5 ° C / min under the protection of an inert gas, and then kept for 1 to 5 hours, naturally cooled, and after cooling. After pulverization and sieving, the high-capacity lithium titanate negative electrode material of the present invention is obtained.

Further, the titanium oxide described in the step (1) is one of anatase type titanium dioxide or a gold stone type titanium dioxide.

Further, the nano tin powder described in the step (1) has a particle diameter of not more than 100 nm.

Further, the resin in the step (1) is one or a mixture of one or more of a phenol resin, an epoxy resin, an alkyd resin, a water-soluble polyester resin, an acrylic resin, and a polybutadiene resin.

Further, the inlet temperature of the spray-dried hot air described in the step (2) is from 150 ° C to 200 ° C, and the outlet temperature is from 40 ° C to 70 ° C.

Further, the inert gas in the step (3) is one of nitrogen gas, argon gas and helium gas.

Beneficial effects:

The invention adopts the nano tin powder, avoids the volume effect of the tin powder due to the large particle size during charging and discharging, ensures the stability of the material during the charging and discharging process, and simultaneously performs the composite coating treatment with the lithium titanate. The utility model solves the defects that the capacity of the single lithium titanate negative electrode material is low; the resin has too many small molecules in the resin during the heat treatment process, and the surface of the coated material generates excessive voids during the overflow process, and the voids can be It acts as a buffer to the volume effect of the tin powder to ensure the stability of the material system. By adding a resin curing agent, hexamethylenetetramine, in the previous step, the resin is thermally cured in the spray drying step, so that it is not melted by the second heat, and the problem of serious agglomeration after high-temperature sintering is avoided.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the 100-cycle capacity retention ratio of a material according to Example 1 of the present invention.

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 the ratio of titanium dioxide: lithium carbonate: nano tin: resin = 100:38:3:10, weigh 1000g of titanium dioxide, 380g of carbon Lithium acid, 30g nano tin, 100g resin, according to the ratio of solid content of 30%, weighed 3523g of ethanol solvent, while adding 3g of hexamethylenetetramine with a resin content of 3%, stirring constantly, mixing into a uniform slurry The slurry is sprayed, dried and classified to obtain a powder having an average particle diameter of 10 μm, and then the powder is heated to 1000 ° C at a rate of 50 ° C/min under the protection of an inert gas, and then kept for 3 hours. The temperature is lowered, and after cooling, the negative electrode material of the high-capacity lithium battery of the present invention is obtained.

Example 2

According to the ratio of titanium dioxide: lithium carbonate: nano tin: resin = 100:40:3:10, weigh 1000g of dioxide, 400g of lithium carbonate, 30g of nano tin, 100g of resin, weigh 3570g according to the solid content of 30% In the ethanol solvent, 3 g of hexamethylenetetramine with a resin content of 3% was added at the same time, and the mixture was continuously stirred and mixed into a uniform slurry; the slurry was sprayed, dried, and classified to obtain a powder having an average particle diameter of 10 μm. Then, the powder is heated to 900 ° C under the protection of inert gas at a rate of 3 ° C / min, and then kept for 3 h, and naturally cooled, and after cooling, the negative electrode material of the high-capacity lithium battery of the present invention is obtained.

Example 3

According to the ratio of titanium dioxide: lithium carbonate: nano tin: resin = 100:40:5:10, weigh 1000g of dioxide, 400g of lithium carbonate, 50g of nano tin, 100g of resin, weigh 3,616g according to the ratio of solid content of 30% In the ethanol solvent, 3 g of hexamethylenetetramine with a resin content of 3% was added at the same time, and the mixture was continuously stirred and mixed into a uniform slurry; the slurry was sprayed, dried, and classified to obtain a powder having an average particle diameter of 10 μm. Then, the powder is heated to 950 ° C under the protection of inert gas at a rate of 5 ° C / min, and then kept for 4 h, and naturally cooled, and after cooling, the negative electrode material of the high-capacity lithium battery of the present invention is obtained.

Comparative example 1

According to the ratio of titanium dioxide: lithium carbonate = 100:40, weigh 1000g of dioxide, 400g of lithium carbonate, weigh 3366g of ethanol solvent according to the ratio of solid content of 30%, stir constantly, mix into a uniform slurry; The slurry is sprayed, dried and classified to obtain a powder with an average particle diameter of 6 μm, and then the powder is heated to 1100 ° C at a rate of 20 ° C/min under the protection of an inert gas, and then kept for 3 hours, naturally cooled, and cooled. After sieving, a lithium titanate negative electrode material is obtained.

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 negative electrode materials of the above examples and comparative examples were used: acetylene black: PVDF (polyvinylidene fluoride) = 93:3:4 (weight ratio), add appropriate amount of NMP (N-methylpyrrolidone) into a slurry, coated on copper foil, dried 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, main features, and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited by the foregoing embodiments, and that the present invention is only described in the foregoing description and the description of the present invention, without departing from the spirit and scope of the invention. Various changes and modifications are intended to be included within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and their equivalents.

Claims

A method for preparing a high-capacity lithium battery anode material, wherein the raw materials are in a proportion by weight, and the method comprises the following steps:

(1) Preparation of precursor slurry: According to the ratio of titanium dioxide: lithium carbonate: nano tin: resin = 100: 38 to 40: 3 to 5: 5 to 10, each component is weighed and dispersed in an organic solvent ethanol to adjust the solid. The content is 20% to 40%, and hexamethylenetetramine with a resin content of 3% to 5% is simultaneously added, and then continuously stirred to obtain a precursor slurry;

(2) atomization, drying, granulation and classification: the precursor slurry prepared in the step (1) is subjected to atomization, drying and granulation, and then subjected to powder classification to obtain an average particle diameter of 5 to 15 μm. Powder

(3) Heat treatment: the powder obtained in the step (2) is heated to a temperature of 800 to 1000 ° C at a rate of 1 to 5 ° C / min under the protection of an inert gas, and then kept for 1 to 5 hours, naturally cooled, and after cooling. After pulverization and sieving, the high-capacity lithium battery anode material of the present invention is obtained.
The method for preparing a high-capacity lithium battery anode material according to claim 1, wherein the titanium dioxide in the step (1) is one of an anatase type titanium dioxide or a gold stone type titanium dioxide.
The method for preparing a high-capacity lithium battery anode material according to claim 1, wherein the nano tin powder in the step (1) has a particle diameter of not more than 100 nm.
The method for preparing a high-capacity lithium battery anode material according to claim 1, wherein the resin in the step (1) is a phenol resin, an epoxy resin, an alkyd resin, a water-soluble polyester resin, or an acrylic acid. One or a mixture of one or more of a resin and a polybutadiene resin.
The method for preparing a high-capacity lithium battery anode material according to claim 1, wherein the inlet temperature of the spray-dried hot air in the step (2) is 150 ° C to 200 ° C, and the outlet temperature is 40. °C ~ 70 °C.
The method for preparing a high-capacity lithium battery anode material according to claim 1, wherein the inert gas in the step (3) is one of nitrogen, argon and helium.