CN102412390A

CN102412390A - Preparation method of Li4Ti5O12 wrapped natural graphite for lithium ion battery cathode

Info

Publication number: CN102412390A
Application number: CN201110307334XA
Authority: CN
Inventors: 路密; 郑晓冬
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-12
Filing date: 2011-10-12
Publication date: 2012-04-11

Abstract

A preparation method of Li4Ti5O12 wrapped natural graphite for lithium ion battery cathode, belonging to the technical field of energy material, wherein the method includes: dispersing the natural graphite into a certain amount of ethanol, adding the stoichiometric tetrabutyl titanate, stirring them to fully absorb on the surface of the natural graphite, slowly adding the water soluble lithium salt, hydrolyzing the tetrabutyl titanate into the TiO2, heating them in the stirring process to volatilize the solvent, uniformly depositing the lithium salt on the surface of the natural graphite, processing the mixtures for 10 h at 800 degrees centigrade under the protection of inert gas to obtain the Li4Ti5O12 wrapped natural graphite. The method has simple process without pollution.

Description

A kind of preparation is used for the Li of lithium ion battery negative 4Ti 5O 12The method of coated natural graphite

Technical field

The invention belongs to the energy and material technical field, be specifically related to a kind of employing spinel-type Li ₄Ti ₅O ₁₂Native graphite is carried out the surface coat, in the hope of improving its chemical property and being used for the method for lithium ion battery negative material.

Background technology

Lithium ion battery is present state-of-the-art chargeable chemical power source system, in digital products such as mobile phone, notebook computer, obtains using the most widely, and is expected to be used widely in the pure electric automobile field of electric tool, hybrid vehicle.But along with the highly-integrated functions of digital product, the specific energy of required battery needs raising by a relatively large margin, and to the electrokinetic cell with uses such as electric tools, except the requirement of energy density, price is one of important considerations.Advantages such as native graphite has specific energy height (greater than 360mAh/g), tap density is high, reserves are abundant, low price both can satisfy the digital product requirement high to the energy density of battery, can also satisfy the requirement that electrokinetic cell reduces price.Therefore, native graphite is one of negative material of the tool potentiality of lithium ion battery.But the coulombic efficiency cycle performance low, material of the circulation first of native graphite is relatively poor, has directly influenced the process of its large-scale commercial applicationsization.Present business-like method is the method that adopts material with carbon element to coat; This method need be heat-treated under higher temperature (greater than 1500 ℃); Higher temperature need consume a large amount of electric energy and handle in the surperficial organic layer carbonisation and also can produce multiple pollutant; Therefore, searching low temperature, green clad material and cladding process have the obvious practical meaning.

Summary of the invention

It is a kind of with spinel-type Li that the object of the invention provides ₄Ti ₅O ₁₂Native graphite is carried out the method for surface coating modification, and with the chemical property that improves native graphite and simplify technology, pollution abatement cuts down the consumption of energy.

The following technical scheme of the concrete employing of the present invention:

A kind of preparation is used for the Li of lithium ion battery negative ₄Ti ₅O ₁₂The method of coated natural graphite is characterized in that, comprises the steps:

Natural graphite powder is scattered in the absolute ethyl alcohol of submergence amount; Stirring also adds the butyl titanate that calculates required stoichiometric proportion according to surperficial covering amount; Stir more than 10 hours to guarantee that butyl titanate is fully adsorbed by graphite surface; The butyl titanate that be adsorbed on graphite surface this moment progressively hydrolysis is produced titanium dioxide; The aqueous solution that slowly adds lithium salts afterwards, heating makes solvent evaporates, and the mixture that obtains at last (mixture of graphite, titanium dioxide and lithium salts) 800 ℃ of processing under inert gas shielding obtained spinel-type Li in 12 hours ₄Ti ₅O ₁₂Coated natural graphite;

Wherein, said graphite and Li ₄Ti ₅O ₁₂Weight ratio be 1-10: 90-99, the mol ratio of lithium salts and butyl titanate is 4: 5.

Described lithium salts is a kind of in lithium acetate, lithium acetate, lithium carbonate, the lithium nitrate.

Described inert gas is argon gas or nitrogen.

Described Li ₄Ti ₅O ₁₂Content be 1-100%.

Among the present invention, absolute ethyl alcohol just serves as solvent, only needs and can the abundant submergence of native graphite be got final product; The water of dissolving lithium salts is mainly used in the hydrolysis of butyl titanate, only needs to guarantee that the abundant hydrolysis of butyl titanate gets final product, and therefore the consumption of absolute ethyl alcohol and water is not done requirement, but consider the cost that practices every conceivable frugality, the consumption of absolute ethyl alcohol and water can not be too many.

Compared with prior art, the invention has the beneficial effects as follows: heat treatment temperature is low, helps reducing the energy consumption of material, thereby reduces the cost of material; Reversible capacity, the cycle performance of gained composite material is improved, irreversible capacity descends; Because Li ₄Ti ₅O ₁₂Be distributed in the surface and hole of graphite, the tap density of material is improved, thereby improve the volume of battery specific energy.

Description of drawings

Fig. 1 is that content is 0%, 1%, 5% and 10%Li ₄Ti ₅O ₁₂The native graphite sem photograph that coats;

Fig. 2 is that content is 0%, 1%, 5% and 10%Li ₄Ti ₅O ₁₂The native graphite X-ray diffractogram that coats;

Fig. 3 is native graphite and 1%Li ₄Ti ₅O ₁₂The native graphite that coats is dressed up the first charge-discharge curve chart of button cell;

Fig. 4 is native graphite and 1%Li ₄Ti ₅O ₁₂The native graphite that coats is dressed up the cycle discharge curve chart of button cell.

Like Fig. 1, shown in 2, Li ₄Ti ₅O ₁₂Be evenly distributed in the native graphite surface, and Li ₄Ti ₅O ₁₂Existence do not change the character of native graphite, only be near 18.4 °, Li to have occurred ₄Ti ₅O ₁₂Diffraction maximum, show that this is a kind of native graphite-Li ₄Ti ₅O ₁₂Composite system.The required heat treatment temperature of the method for this coating is low, in heat treatment process except CO ₂Outer do not have other pollutant and produce, and is a kind of cheapness, that be easy to amplify production, free of contamination native graphite surface method for coating.

Embodiment

Further set forth the present invention below in conjunction with specific embodiment.

Embodiment

A kind of native graphite coats total weight 1%Li ₄Ti ₅O ₁₂Method; Described method is that the native graphite that at first takes by weighing respective amount is measured a certain amount of absolute ethyl alcohol then and is placed in the container in container; The amount of absolute ethyl alcohol is crossed native graphite with submergence and is as the criterion; Add the butyl titanate of aequum afterwards and stirred 10 hours so that butyl titanate fully is adsorbed on the native graphite surface, slowly splash into an amount of water-soluble lithium acetate afterwards, the adding of water is for making tetrabutyl titanate hydrolysis; Water dissolving lithium acetate is in order to make lithium acetate in dry run subsequently, fully be adsorbed on the native graphite surface; After treating that tetrabutyl titanate hydrolysis is accomplished, heating in whipping process is so that dissolving is volatilized, and the mixture that obtains at last 800 ℃ of processing under argon shield obtained 1%Li in 10 hours ₄Ti ₅O ₁₂The native graphite that coats.

Like Fig. 3, shown in 4,1%Li ₄Ti ₅O ₁₂The reversible capacity first of material is brought up to 357.5mAh/g from the 318.1mAh/g of native graphite after coating, and coulombic efficiency brings up to 88.6% from 87.3% of native graphite first; To bring up to performance that the 359.1mAh/g. another one significantly improves be total irreversible capacity loss to high reversible capacity is reduced to 103.9mAh g-1 from the 122.8mAh/g of native graphite from the 337.4mAh/g of native graphite.

The content that adopts the preparation of identical method is 5% and 10%Li ₄Ti ₅O ₁₂ESEM and X-ray diffractogram also in Fig. 1 and Fig. 2, list.

The Li that in like manner can prepare other content ₄Ti ₅O ₁₂-native graphite compound.

Claims

1. one kind prepares the Li that is used for lithium ion battery negative ₄Ti ₅O ₁₂The method of coated natural graphite is characterized in that, comprises the steps:

Natural graphite powder is scattered in the absolute ethyl alcohol of submergence amount; Stirring also adds the butyl titanate that calculates required stoichiometric proportion according to surperficial covering amount; Stir more than 10 hours; The aqueous solution that slowly adds lithium salts afterwards, heating makes solvent evaporates, and the mixture that obtains 800 ℃ of processing under inert gas shielding obtained spinel-type Li in 12 hours ₄Ti ₅O ₁₂Coated natural graphite;

2. preparation according to claim 1 is used for the Li of lithium ion battery negative ₄Ti ₅O ₁₂The method of coated natural graphite is characterized in that, described lithium salts is a kind of in lithium acetate, lithium acetate, lithium carbonate, the lithium nitrate.

3. preparation according to claim 1 is used for the Li of lithium ion battery negative ₄Ti ₅O ₁₂The method of coated natural graphite is characterized in that, described inert gas is argon gas or nitrogen.

4. preparation according to claim 1 is used for the Li of lithium ion battery negative ₄Ti ₅O ₁₂The method of coated natural graphite is characterized in that, described Li ₄Ti ₅O ₁₂Content be 90-99%.