CN101456581A

CN101456581A - Method for preparing lithium ion secondary battery cathode material lithium titanate containing rare-earth element

Info

Publication number: CN101456581A
Application number: CNA2009100764866A
Authority: CN
Inventors: 其鲁; 王兴勤; 王昕�
Original assignee: CITIC Guoan Mengguli New Energy Technology Co Ltd
Current assignee: CITIC Guoan Mengguli New Energy Technology Co Ltd
Priority date: 2009-01-05
Filing date: 2009-01-05
Publication date: 2009-06-17

Abstract

The invention belongs to the technical field of lithium ion secondary battery critical material, and relates to a method for preparing a lithium ion secondary battery cathode material containing rare earth elements (such as La, Ce, Pr, Nd, Sm, Dy and Ho), namely spinel lithium titanate. The method adopts titania, a lithium salt and rare earth oxide as raw materials and a high-temperature solid-phase method to synthesize the lithium battery cathode material, namely the spinel lithium titanate, through reaction. An analog battery, which is prepared by synthesizing the lithium metals and rare earth elements which are mixed by a wet-process mechanical ball milling method, has initial specific capacity which reaches 173 mAh/g (0.2Cvs.Li/Li<+>), superior cycle performance and low cost, and is particularly suitable for industrial mass production. The synthesized lithium titanate product has stable performance, superior cycle performance, good consistence and wide application prospect, and the capacity conservation rate of the lithium titanate product is more than 99 percent after the lithium titanate product is cycled for 200 times.

Description

A kind of preparation method who contains the lithium ion secondary battery cathode material lithium titanate of rare earth element

Technical field

The present invention relates generally to a kind of synthetic method that contains rare earth element ion secondary battery cathode material lithium spinel type lithium titanate, belongs to lithium ion battery critical material and technical field.

Background technology

Along with development of science and technology, various portable type electronic products are universal day by day, and developing electromobile etc. are had higher requirement to all many-sides such as the energy density of battery power, work-ing lifes.In all batteries, characteristics such as lithium ion battery has voltage height, specific energy height, has extended cycle life, non-environmental-pollution, be widely used in the portable electric appts such as mobile telephone, notebook computer, also will be used widely in fields such as electromobile, satellite and space flight.But also there are some problems in lithium ion battery at present, for example has certain potential safety hazard, and the electropotential of carbon dioxide process carbon electrode and metallic lithium is close, when battery overcharge, still may form dendrite at carbon electrodes precipitating metal lithium and cause short circuit.So the current potential with respect to lithium electrode is " zero strain " material lithium-titanium composite oxide Li of 1.55v ₄Ti ₅O ₁₂Become the focus of research gradually.Crystalline structure can keep the stability of height to make it have good cycle performance and sparking voltage stably in the process that this material embeds at lithium ion-deviates from.Thereby owing to have the generation that higher electrode voltage has been avoided electrolyte decomposition phenomenon or protective membrane, safety performance is good, and preparation Li ₄Ti ₅O ₁₂Raw material sources abundanter, so Li ₄Ti ₅O ₁₂A kind of more satisfactory lithium ion battery negative material that can replace carbon of can yet be regarded as.

Because the specific conductivity of lithium titanate material is low, can improve its fast charging and discharging performance and high rate during charging-discharging by mixing, as patent 200680009969.9, but electrochemical capacity is relatively poor.

Summary of the invention

The objective of the invention is to use raw material at a low price, short time and lower synthesis temperature, the lithium ionic cell cathode material lithium titanate of synthetic chemical property excellence; This method synthetic product, have higher specific storage and excellent cycle performance, favorable reproducibility, with low cost, preparation technology simple, not high to equipment requirements.

A kind of preparation method of lithium ionic cell cathode material lithium titanate may further comprise the steps:

(1) lithium salts, titanium dioxide and rare earth oxide are carried out batch mixing with ball milling method, add dispersion agent ball milling 0.5～10h, then the uniform slurry of solids of ball milling is removed dispersion agent with microwave drying, obtain presoma until mixing;

(2) presoma for preparing is carried out pyroprocessing in retort furnace, treatment temp is 300～700 ℃, and the treatment time is 0.5～5 hour;

(3) product of step (2) gained is naturally cooled to room temperature after, pulverized 150 mesh sieves;

(4) the crushing screening after product is carried out pyroprocessing, treatment temp is 300～1100 ℃, and the treatment time is 0.5～16 hour, treat naturally cooling after, the institute synthetic materials is taken out, pulverized behind 150 mesh sieves the finished product.

Described lithium salts is a kind of or its mixture in Quilonum Retard, lithium hydroxide and the lithium nitrate; The structure of described titanium dioxide is anatase titanium dioxide or rutile-type; Described rare earth oxide is a kind of or wherein multiple mixture in lanthanum trioxide, cerium oxide, Praseodymium trioxide, Neodymium trioxide, Samarium trioxide, dysprosium oxide and the Holmium trioxide; Described dispersion agent is methyl alcohol or ethanol, or the mixture of methyl alcohol or ethanol and water.

The mol ratio of lithium salts described in the step (1) and titanium dioxide is 0.7～1.2, and is benchmark with the gross weight of lithium salts, titanium dioxide and three kinds of raw materials of rare earth oxide, and rare earth oxide accounts for 0.01～3wt%.

Pyroprocessing described in the step (4) at first is warming up to 300～550 ℃ for to be incubated processing under 3 temperature sections, is incubated 0.5～3 hour, then be warming up to 700～1100 ℃, be incubated 1～10 hour, at last material be cooled to 300 ℃～600 ℃, continue insulation 0.5～3 hour.

A kind of lithium ion battery negative material according to the preceding method preparation, wherein the synthetic lithium titanate material contains one or more rare earth elements, described rare earth element is La, Ce, Pr, Nd, Sm, Dy or Ho, and wherein rare earth element is in oxide compound, and content is 0.01～3wt%.

Of the present invention having the following advantages: 1) institute's synthetic excellent material performance, circulation ratio, high conformity 2) used starting material wide material sources are cheap; 3) generated time is short, can realize the quick preparation of material; 4) preparation technology of material is simple, is adapted to the requirement of commercial scale production.

Description of drawings:

Fig. 1 is 4 synthetic spinels of embodiment Li ₄Ti ₅O ₁₂The SEM figure of material;

Fig. 2 is 4 synthetic spinels of embodiment Li ₄Ti ₅O ₁₂XRD comparison diagram with standard diagram;

Fig. 3 is 4 synthetic spinels of embodiment Li ₄Ti ₅O ₁₂Cyclic curve (the vs.Li/Li of material ⁺);

Fig. 4 is embodiment 4 described spinel Li ₄Ti ₅O ₁₂First charge-discharge voltage curve (vs.Li/Li ⁺).

Embodiment

Describe the present invention in detail below by specific embodiment:

Embodiment 1

Selecting lithium hydroxide, anatase titanium dioxide and cerium oxide for use is raw material, and wherein the mol ratio of lithium hydroxide and anatase titanium dioxide is 0.8:1, and cerium oxide accounts for the 1wt% of three kinds of raw materials.With three kinds of mixing raw materials, add the methyl alcohol dispersion agent, ball milling is 6 hours on ball mill, gets presoma after the microwave drying.It is as follows that presoma is done further processing: under air atmosphere prior under 500 ℃, pyroprocessing 2h, cooling back ball milling is crossed 150 mesh sieves, the after product that sieves is warming up to 800 ℃ of insulation 8h behind the insulation 2h down in 500 ℃ more again under air atmosphere, be cooled to 600 ℃ of insulation 2h subsequently again, cooling back ball milling is crossed 150 mesh sieves and is got the lithium titanate sample.Observe through scanning electronic microscope (SEM), material particles is even, and is tiny; After X-ray powder diffraction (XRD) test is the lithium titanate of single phase spinel structure; PH value is 10.8; Through particle D50 after the sreen analysis is about 5um.

The lithium titanate that will synthesize, acetylene black and electrically conductive graphite, caking agent poly(vinylidene fluoride) PVDF by mass ratio 90:4:6 (wherein acetylene black and electrically conductive graphite and, account for total proportion 4%) mix, be coated on the aluminium foil, be cut into pole piece after the drying.Ionogen LiPF6 salt is dissolved in the mixing solutions of the NSC 11801 that volume ratio is 1:1 (EC)/methylcarbonate (DMC) and forms electrolytic solution, the concentration of electrolytic solution is 1 mol, with the metallic lithium is counter electrode, in being full of the vacuum glove box of argon gas, be assembled into button cell, carry out electrochemical property test.Charge-discharge magnification is 0.2C first, is 1.0C later on for the second time, and voltage range is 0.8～2.5V, and reversible specific capacity is 163mAh/g first, but repeatedly decay appears in circulation back capacity, and 100 times the back capability retention that circulates is 96%.

Embodiment 2

Selecting Quilonum Retard, anatase titanium dioxide and Neodymium trioxide for use is raw material, and wherein the mol ratio of Quilonum Retard and anatase titanium dioxide is 0.85:1, and Neodymium trioxide accounts for the 3wt% of three kinds of raw materials.With three kinds of mixing raw materials, add alcohol dispersant, ball milling is 7 hours on ball mill, gets presoma after the microwave drying.Presoma is done further processing with embodiment 1, observes through scanning electronic microscope (SEM), and material particles is even, and is tiny; After X-ray powder diffraction (XRD) test is the lithium titanate of single phase spinel structure; PH value is 10.5; Through particle D50 after the sreen analysis is about 4um.

The preparation of pole piece, the assembling of button cell and electrochemical property test are with embodiment 1.The first discharge specific capacity of sample is 160mAh/g, the cycle performance excellence of material.

Embodiment 3

Selecting lithium hydroxide, rutile titanium dioxide, Holmium trioxide and cerium oxide for use is raw material, and wherein the mol ratio of lithium hydroxide and rutile titanium dioxide is 0.8:1, and Holmium trioxide and cerium oxide respectively account for the 0.5wt% of raw material total amount.With various mixing raw materials, add the methyl alcohol dispersion agent, ball milling is 6 hours on ball mill, gets presoma after the microwave drying.Presoma is done further processing with embodiment 1.Observe through scanning electronic microscope (SEM), material particles is even, and is tiny; After X-ray powder diffraction (XRD) test is the lithium titanate of single phase spinel structure; PH value is 10.9; Through particle D50 after the sreen analysis is about 5um.

The preparation of pole piece, the assembling of button cell and electrochemical property test are with embodiment 1.The first discharge specific capacity of sample is 150mAh/g, the cycle performance excellence of material.

Embodiment 4

Selecting lithium hydroxide, anatase titanium dioxide and cerium oxide for use is raw material, and wherein lithium hydroxide is 0.9:1 with the mol ratio of, anatase titanium dioxide, and cerium oxide accounts for the 1wt% of raw material total amount.With various mixing raw materials, add the methyl alcohol dispersion agent, ball milling is 8 hours on ball mill, gets presoma after the microwave drying.Presoma is done further processing with embodiment 1.Through sem observation, material granule is evenly tiny; Detect the lithium titanate that product has generated single phase spinel structure through X-ray diffraction; PH value is 10.9; Through particle D50 after the sreen analysis is about 2um.

The preparation of pole piece, the assembling of button cell and electrochemical property test are with embodiment 1.The first discharge specific capacity of sample is 173mAh/g, the cycle performance excellence, and capability retention is 99.3% after 100 circulations.

Claims

1, a kind of preparation method of lithium ionic cell cathode material lithium titanate is characterized in that, comprises the steps:

(1), lithium salts, titanium dioxide and rare earth oxide are carried out batch mixing with ball milling method, add dispersion agent ball milling 0.5～10h, then the uniform slurry of solids of ball milling is removed dispersion agent with microwave drying, obtain presoma until mixing;

(2), the presoma for preparing is carried out pyroprocessing in retort furnace, treatment temp is 300～700 ℃, and the treatment time is 0.5～5 hour;

(3), the product of step (2) gained naturally cooled to room temperature after, pulverize the back and cross 150 mesh sieves;

(4), the crushing screening after product is carried out pyroprocessing, treatment temp is 300～1100 ℃, and the treatment time is 0.5～16 hour, treat naturally cooling after, institute's synthetic materials is taken out, pulverized behind 150 mesh sieves the finished product.

2, method according to claim 1, described lithium salts are a kind of or its mixture in Quilonum Retard, lithium hydroxide and the lithium nitrate; The structure of described titanium dioxide is anatase titanium dioxide or rutile-type; Described rare earth oxide is a kind of or wherein multiple mixture in lanthanum trioxide, cerium oxide, Praseodymium trioxide, Neodymium trioxide, Samarium trioxide, dysprosium oxide and the Holmium trioxide; Described dispersion agent is methyl alcohol or ethanol, or the mixture of methyl alcohol or ethanol and water.

3, method according to claim 1 is characterized in that, the mol ratio of lithium salts and titanium dioxide is 0.7～1.2 in the step (1), and is benchmark with the gross weight of lithium salts, titanium dioxide and three kinds of raw materials of rare earth oxide, and rare earth oxide accounts for 0.01～3wt%.

4, method according to claim 1, it is characterized in that, pyroprocessing described in the step (4) is for being incubated processing under 3 temperature sections, at first be warming up to 300～550 ℃, be incubated 0.5～3 hour, then be warming up to 700～1100 ℃, be incubated 1～10 hour, at last material is cooled to 300 ℃～600 ℃, continues insulation 0.5～3 hour.

5, a kind of lithium ion battery negative material of method preparation according to claim 1, it is characterized in that, the synthetic lithium titanate material contains one or more rare earth elements, described rare earth element is La, Ce, Pr, Nd, Sm, Dy or Ho, wherein rare earth element is in oxide compound, and content is 0.01～3wt%.