CN100426568C

CN100426568C - Method of synthesizing lithium ion cathode material lithium titanium oxide using solvent heating method

Info

Publication number: CN100426568C
Application number: CNB2006100121976A
Authority: CN
Inventors: 赵海雷; 李玥; 仇卫华; 李雪
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2006-06-12
Filing date: 2006-06-12
Publication date: 2008-10-15
Anticipated expiration: 2026-06-12
Also published as: CN1868891A

Abstract

The present invention relates to a method for synthesizing lithium ion cathode material lithium titanium oxide by a solvent heating method, which belongs to the field of a lithium ion battery. The process has the steps that an alcoholic solution with anhydrous lithium hydroxide and butyl titanate is put in an autoclave which is heated to 100 to 180 DEG C, constant temperature is kept for 10 to 72 hours, and after an air or water cooling process, a reaction system carries out filtration, washing and drying, and then an amorphous lithium titanium oxide powder body is obtained. The present invention has the advantages of simple preparation equipment and process, and low cost, and is suitable for industrialization large-scale production; the synthesizing sample has a stable structure and excellent cycle performance, and the conservation rate of the capacity of 20 cycles is 100 %.

Description

The method of solvent-thermal method synthesizing lithium ion cathode material lithium titanium oxide

Technical field

The invention belongs to the lithium ion battery field, a kind of method of solvent-thermal method synthesizing lithium ion cathode material lithium titanium oxide is provided especially.

Background technology

Characteristics such as lithium ion battery has energy density height, operating voltage height, load characteristic is good, charging rate is fast, have extended cycle life, memoryless, safety non-pollution are widely used in fields such as portable communication apparatus, Aero-Space, space military affairs, energy storage facility at present.At present, the fast development of portable electric appts, EV (electric automobile), HEV (hybrid-electric car) and space technology is had higher requirement at aspects such as specific capacity, cycle life, fail safes to secondary cell.The chemical property of improvement and raising battery can be started with from many-sides such as electrode material, electrolyte.

At present the negative material of commercialization lithium ion battery is a carbon materials, because it is very approaching with the current potential of lithium metal to insert behind the lithium current potential of carbon electrode, and most electrolyte is instability under this current potential, and electrolyte easily decomposes at electrode surface.When over-charging of battery, carbon electrodes is easily separated out very active lithium metal, and it and electrolyte reaction produce combustible gas mixture.Under limiting case, excessive lithiated carbon anode can catch fire and produce blast, thereby causes very big potential safety hazard for battery, particularly electrokinetic cell.Simultaneously, also there is the common insertion problem of electrolyte in graphite electrode, and this also will influence the cyclical stability of electrode.At this moment, seek embed lithium under than the positive slightly current potential of carbon negative pole current potential, cheap and easy to get, safe and reliable novel negative material is necessary and urgent.Wherein electronegative potential transition metal oxide and composite oxides have caused people's extensive attention, Li as the negative material of lithium ion battery ₄Ti ₅O ₁₂It is one of material of wherein extensively being paid close attention to.

Novel negative material Li ₄Ti ₅O ₁₂The theoretical specific capacity of electrode is 175mAh/g, is 1.5V with respect to the voltage platform of lithium, is higher than most of electrolytical recovery voltages, so Li ₄Ti ₅O ₁₂Has extraordinary security performance as lithium ion battery negative material.With LiMn ₂O ₄Perhaps LiCoO ₂Electrode composition battery can provide the voltage about 2.5V, is NI-G or Ni-MH battery 2 times.In addition, lithium embeds and Li when taking off embedding ₄Ti ₅O ₁₂Cell parameter and change in volume very little, be a kind of zero strain material, so, Li ₄Ti ₅O ₁₂Has superior cycle performance, efficiency for charge-discharge no better than 1.Thereby Li ₄Ti ₅O ₁₂It is a kind of lithium ion battery negative material of safe, function admirable.

Prepare Li at present ₄Ti ₅O ₁₂Take traditional solid reaction process mostly, with TiO ₂, Li ₂CO ₃Or LiOHH ₂O is a raw material, synthetic about 800-1000 ℃ (Prosini P P and Mancini R, Solid State Ionics, 2001,144:185-192).Though this method has the advantage of large-scale production, resulting material generally has agglomeration, the particle size distribution inequality, and particle is bigger, the internal resistance of battery is big, polarization is more serious so cause.So improved solid phase synthesis adopts the high-energy ball milling batch mixing, though obtain meticulous Li ₄Ti ₅O ₁₂Particle, but this method energy consumption is bigger.Sol-gel process prepares Li ₄Ti ₅O ₁₂Be present synthesis of nano Li ₄Ti ₅O ₁₂Main method.The researcher is arranged to the synthetic Li of this method ₄Ti ₅O ₁₂Conditions such as mechanism, pH value of solution value, complexing agent consumption, sintering processing and temperature carried out system research (U.S.20040197657A1) (U.S.09595958) (U.S.20040202934A1).Nanometer Li ₄Ti ₅O ₁₂Because its tiny grain is brilliant and homogeneous granules distributes, under electric current greatly, show higher capacity and cyclical stability preferably, all more stable as its resistance of electrode, current density and reactiveness, overall performance is good.But the shortcoming of this kind method is except adopting expensive metal organic salt, synthetic complex technical process, and the condition strictness, synthetic powder still needs to carry out high-temperature process going out organic group, and the discharging efficiency first of gained powder is not high.Adopting low-temperature hydrothermal lithium ion exchange process also successful at present is the forerunner with nanotube (line, rod, band) metatitanic acid, has synthesized good nanotube, the nano wire Li of chemical property ₄Ti ₅O ₁₂(J.Li and Z, tangetal, Electrochemistry Communications, 2005,7:894-899).In addition, A.Singhal etc. has synthesized nanoscale TiO with vapor phase method ₂Particle is then by CF-CVC (combustion flame-chemical vapor condensation) method and LiNO ₃Synthesizing superfine Li ₄Ti ₅O ₁₂Powder (Singhal A and Skandan G, J PowerSources, 2004,129:38-44).But these method complex process all are not suitable for industrial mass production.

In a word, nanometer Li ₄Ti ₅O ₁₂Have good cyclical stability, especially when high current charge-discharge, show excellent performance.But at synthesis of nano Li ₄Ti ₅O ₁₂The aspect lacks easily row of a kind of operation, is fit to industrialized production method.The invention provides a kind of amorphous Li ₄Ti ₅O ₁₂Synthetic method, this method is with low cost, and is reliable and stable, technology is simple.The amorphous Li of preparation ₄Ti ₅O ₁₂Show good cyclical stability and high magnification characteristic preferably.

Summary of the invention

The object of the present invention is to provide solvent thermal to synthesize amorphous Li ₄Ti ₅O ₁₂The method of ion cathode material lithium.Make under anhydrous lithium hydroxide and the butyl titanate low temperature and in alcoholic solution, react, obtain unbodied Li-Ti oxide.

Technology of the present invention is:

A, select for use and analyze pure or industrial butyl titanate and anhydrous LiOH powder is prepared by atomic ratio Li/Ti=0.8～1.2;

B. the addition of lithium is placed on reactant and solvent in the autoclave at 0.01～4mol/100ml solvent, and the cumulative volume of reaction system is 60%～80% of a reaction vessel volume; The employing monohydric alcohol is a solvent.

C, solvent thermal synthesis condition are: autoclave is heated to 100～180 ℃, is incubated 10～72 hours, with the autoclave air cooling or be cooled to room temperature.

D. open autoclave, product is filtered, and adopt solvent wash 2-6 time, 50-100 ℃ of oven dry down, can obtain amorphous Li then ₄Ti ₅O ₁₂Powder.

Cleaning solvent of the present invention is: monoalcohol solvent.

The invention has the advantages that preparation equipment and technology are simple, it is capable of reducing energy consumption to need not high-temperature process, and cost is low, is fit to large-scale industrial production.The synthetic sample Stability Analysis of Structures, the cyclical stability excellence, 20 circulation volume conservation rates are near 100%.

Description of drawings

Fig. 1 is the synthetic amorphous Li-Ti oxide XRD figure of solvent thermal of the present invention, and it is solvent with ethanol, and the Li/Ti atomic ratio is 1, and 120 ℃ of insulations of solvent thermal air cooling in 48 hours prepares Li ₄Ti ₅O ₁₂Powder.

Fig. 2 is the capacity one cycle-index curve of the present invention at 48 hours synthetic amorphous Li-Ti oxides of 120 ℃ of insulations.Wherein the Li/Ti atomic ratio is 0.8, and charging and discharging currents density is 1C.

Fig. 3 is the capacity one cycle-index curve of the present invention at 24 hours synthetic amorphous Li-Ti oxides of 140 ℃ of insulations.Wherein the Li/Ti atomic ratio is 0.8, and charging and discharging currents density is: preceding 10 times for 1C, middle 10 times is 10C, reverts to 1C again last 10 times.

Embodiment

Example 1: with anhydrous LiOH (purity＞95%) and butyl titanate (purity＞98%) is raw material, respectively gets 0.1mol, is dissolved in the 100ml absolute ethyl alcohol.It is the poly-tetrafluoro liner self-tightening type autoclave of 200ml that mixed liquor is placed volume, and autoclave is placed 120 ℃ of insulating boxs (the still internal pressure can reach 423.9kPa), be incubated air cooling after 48 hours, sample after the absolute ethanol washing filter 23 is inferior, 50 ℃ of oven dry.To the Li that obtains ₄Ti ₅O ₁₂Powder carries out the XRD material phase analysis, and the result shows that synthetic Li-Ti oxide tool impalpable structure tentatively possesses Li ₄Ti ₅O ₁₂Characteristic peak.

With the conductive agent acetylene black of synthetic amorphous Li-Ti oxide adding 10wt%, the polyfluortetraethylene of binding element of 5wt% is made slurry, suppresses film forming, blocks into the circular pole piece of diameter 1cm, forms test cell with lithium metal.Test cell is carried out the constant current charge-discharge experiment, and charging and discharging currents is 1C, and the charging/discharging voltage scope is controlled between 1.0～2.3V.The reversible capacity of the amorphous negative material of preparation is about 80mAh/g, and is except that 20% irreversible capacity first, undamped through 20 circulation volumes.

Example 2: with anhydrous LiOH (purity＞95%) and butyl titanate (purity＞98%) is raw material, gets 0.08mol and 0.1mol respectively, is dissolved in the 100ml absolute ethyl alcohol.It is the poly-tetrafluoro liner self-tightening type autoclave of 200ml that mixed liquor is placed volume, and autoclave is placed 140 ℃ of insulating boxs (the still internal pressure can reach 747.4kPa), be incubated air cooling after 24 hours, sample after the absolute ethanol washing filter 23 is inferior, 50 ℃ of oven dry.To the Li that obtains ₄Ti ₅O ₁₂Powder carries out the XRD material phase analysis, and the result shows that synthetic Li-Ti oxide tool impalpable structure tentatively possesses Li ₄Ti ₅O ₁₂Characteristic peak.

With the conductive agent acetylene black of synthetic amorphous Li-Ti oxide adding 10wt%, the polyfluortetraethylene of binding element of 5wt% is made slurry, suppresses film forming, blocks into the circular pole piece of diameter 1cm, forms test cell with lithium metal.Test cell is carried out the constant current charge-discharge experiment, voltage range is controlled between 1.0～2.3V, charging and discharging currents adopts 1C preceding 10 times, then the electric current with 10C charges and discharge 10 times, getting back to 1C then again charges and discharge 10 times, the amorphous Li-Ti oxide negative material of preparation shows good cyclical stability, and behind the 10C high current charge-discharge, discharging and recharging its capacity under 1C again can 100% recovery.

Claims

1, a kind of method of solvent-thermal method synthesizing lithium ion cathode material lithium titanium oxide is characterized in that: technology is:

B. the addition of lithium is placed on reactant and solvent in the autoclave at 0.01～4mol/100ml solvent, and the cumulative volume of reaction system is 60%～80% of a reaction vessel volume; Solvent is-unit's alcohol;

C, solvent thermal synthesis condition are: autoclave is heated to 100～180 ℃, is incubated after 10～72 hours, with the autoclave air cooling or be cooled to room temperature;

D. open autoclave, product is filtered, and adopt solvent wash 2-6 time, 50-100 ℃ of oven dry down, obtain amorphous Li then ₄Ti ₅O ₁₂Powder.

2, in accordance with the method for claim 1, it is characterized in that: cleaning solvent is: the unary alcohol solvent.