CN108448085A - Lithium titanate-carbon nano tube compound material and preparation method thereof, lithium ion battery - Google Patents
Lithium titanate-carbon nano tube compound material and preparation method thereof, lithium ion battery Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- H—ELECTRICITY
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Abstract
The present invention relates to the preparation methods of lithium titanate carbon nano tube compound material, including forerunner's preparation step：Carbon nanotube, organic titanium source and lithium source are placed in the dicyandiamide solution of absolute alcohol and reacted, the presoma of lithium titanate carbon nano tube compound material is obtained；Calcining step：Presoma is calcined, lithium titanate carbon nano tube compound material is obtained.Its lithium titanate of composite material prepared by the method for the present invention is uniform graininess, and compound uniformity is more preferable, lithium titanate particle is tiny, and materials conductive rate is obviously improved, when as lithium ion battery negative material, excellent big high rate performance and electrochemical cycle stability are shown.Lithium battery the present invention also provides lithium titanate carbon nano tube compound material and to be made of the material.
Description
Technical field
The present invention relates to a kind of electrode material technical field, especially a kind of lithium titanate-carbon nano tube compound material and its
Preparation method.
Background technology
Lithium ion battery has the characteristics that energy density is high, has extended cycle life, memory-less effect, pollution-free to bad border,
Through being widely used on portable electronic device and power vehicle, the most widely used cathode material of commercial Li-ion batteries at present
Material is graphite, however, in charge and discharge process, graphite cathode has a lower voltage platform, negative terminal surface during removal lithium embedded
It is easy to form Li dendrite, battery diaphragm can be punctured, so as to cause the serious security risk such as short circuit.Safety problem be current lithium from
Sub- battery is badly in need of the critical issue solved.
Lithium titanate (the Li of spinel structure4Ti5O12, LTO) exist in charge and discharge processReaction,
From Li4Ti5O12It is transformed into Li7Ti5O12, but the cell parameter for reacting front and back the two is very close, has " zero strain " characteristic,
And the discharge voltage plateau of LTO is 1.55V (vs Li/Li+), there can be high safety to avoid the generation of Li dendrite,
It is a kind of ideal lithium ion battery negative material.
However, Li4Ti5O12The intrinsic conductivity of material is 10-13S cm-1, the diffusion coefficient of lithium ion is about 10-9~
10-13cm2s-1, poor and weak conductivity and the diffusion of lower lithium ion largely limit its answering under conditions of high current
With.In order to solve this problem, many researchers attempt the nanometer Li for being prepared for different morphologies4Ti5O12, such as it is hexahedral
The core-shell particles etc. of structure microspheres, nanometer sheet composition.These methods are mainly by Li4Ti5O12Nanosizing, shorten lithium ion and
The transmission path of electronics, to improve the kinetics of material.Another method is by Li4Ti5O12With conduct electricity very well
Carbon material progress is compound, can not only improve the electric conductivity of material, polarization phenomena and mesh effectively under the conditions of reduction high current
The Main way of preceding research.For example, a Chinese patent application discloses a kind of preparation side of carbon coating lithium titanate composite material
Method, process are to prepare lithium titanate material using solid phase method first, then again by the lithium titanate material and carbon source of above-mentioned gained
Mixing, obtains presoma by hydro-thermal reaction, then obtains carbon coating lithium titanate composite material using high-temperature heat treatment.It is another
Part Chinese patent application discloses a kind of preparation method of carbon coating lithium titanate composite material, and process is first by lithium source, carbon
Source is dissolved in the water to form premixed liquid, and a certain amount of organic titanium source is then added thereto, in being formed by stirring, Centrifugal dispersion
Mesosome gel, then nanocomposite is formed with broken by high-temperature calcination.
However, the method for the preparation carbon coating lithium titanate of above-mentioned first patent application publication is sufficiently complex, and it is first
Lithium titanate is prepared using solid phase method, lithium titanate prepared by this method is easy to agglomerate, using hydro-thermal method reaction process,
High-temperature heat treatment obtains carbon encapsulated material, the carbon encapsulated material that this kind of method obtains be not easy uniformly, the consistency of material it is poor.And
The method that above-mentioned second patent application discloses need to form intermediate gel by stirring and centrifugal method, form gelinite
During, the uniformity of gel component it is difficult to ensure that, cause the uniformity of the carbon encapsulated material prepared below consistent with material
Property it is poor, and the granular size of material be difficult control, it is difficult to realize industrialized production.
Invention content
Preparation process in order to solve existing carbon coating lithium titanate composite material is complicated, compound uniformity is poor, material one
Cause property is difficult to ensure, the problems such as chemical property is unstable, and it is simple that the present invention provides a kind of preparation method, compound uniformity is good,
Material consistency and the high lithium titanate carbon nano-composite material of nanosizing degree, to effectively improve the electric conductivity of lithium titanate material,
Method simple reaction process is easily controllable, is suitable for large-scale production promotes and applies.
In order to solve the above problem of the prior art, the present invention provides a kind of system of lithium titanate-carbon nano tube compound material
Preparation Method, the method includes：
Forerunner's preparation step：Carbon nanotube, organic titanium source and lithium source are placed in the dicyandiamide solution of absolute alcohol and reacted, is obtained
Obtain the presoma of the lithium titanate-carbon nano tube compound material；
Calcining step：The presoma is calcined, the lithium titanate-carbon nano tube compound material is obtained.
In an embodiment of the invention, forerunner's preparation step includes：
The organic titanium source of certain amount of substance is added in absolute alcohol and is configured to the anhydrous alcohol solution containing organic titanium, by an earnest
The lithium source of quality is added in absolute alcohol and is configured to the anhydrous alcohol solution containing lithium；
The carbon nanotube of certain mass is added in one of aforementioned two kinds of solution and is homogenized and is operated
To the first solution, then another kind is defined as the second solution in aforementioned two kinds of solution；
Second solution is added in first solution, and the amount of substance ratio of titanium and lithium in mixed system is made to be 5:
4~5:4.2, after being heated to 120~180 DEG C of reaction 16-36h in a sealed meter environment, solid particulate matter is isolated, the titanium is obtained
The presoma of sour lithium-carbon nano tube compound material.
Wherein, organic titanium source is organic acid, the Organic Alcohol of titanium or the organic ester of titanium of titanium；The organic ester of the titanium is metatitanic acid
Isopropyl ester, butyl titanate, tetraethyl titanate or tetrabutyl titanate.
Preferably, the organic titanium is configured to the anhydrous alcohol solution of 0.15~0.2mol/L with absolute alcohol；Preferably 0.15
The anhydrous alcohol solution of~0.18mol/L.
Wherein, described to homogenize operation to be ultrasonically treated 2h~4h.
Wherein, lithium source is lithium acetate, lithium hydroxide or lithia.The lithium source and absolute alcohol be configured to 0.3mol/L~
The anhydrous alcohol solution of 0.6mol/L；The preferably anhydrous alcohol solution of 0.4~0.45mol/L.
Preferably, in forerunner's preparation step, keep carbon nanotube, organic titanium source and lithium source three molten in absolute alcohol
Liquid carries out solvent-thermal method reaction, obtains precursor powder.Wherein, the solvent-thermal method refers in enclosed system such as autoclave, with
Organic matter or non-aqueous solvent are solvent, under the self-generated pressure of certain temperature and solution, original stock reacted one
Kind synthetic method.The more excellent condition of solvent-thermal method reaction is, is 120 DEG C~140 DEG C in sealed environment and temperature, and the reaction time is
20~28 hours.Reaction time and temperature condition can influence the titanium loaded in carbon nanotube in final product to a certain extent
The quality and lithium titanate granule size of sour lithium.
In an embodiment of the invention, the absolute alcohol is the alcohol being in a liquid state under room temperature.
In an embodiment of the invention, the absolute alcohol is selected from least one of following：Ethyl alcohol, propyl alcohol and butanol.
In an embodiment of the invention, the carbon nanotube is oxidized property acid treated carbon nanotube.
In an embodiment of the invention, the oxidizing acid is the mixture of sulfuric acid, nitric acid or sulfuric acid and nitric acid.Example
Such as, sulfuric acid is 1 by volume with nitric acid：3 mix.
In an embodiment of the invention, the oxidizing acid, which is handled, is：A certain amount of carbon nanotube is taken to be added to oxidation
Property acid solution in, be heated to reflux a period of time, be dried to obtain after filtering acid processing carbon nanotube.
In an embodiment of the invention, the calcining step is：Before the lithium titanate-carbon nano tube compound material
It drives body to be placed in inert atmosphere, and is calcined at 650-850 DEG C, obtain Li4Ti5O12Carbon nano tube compound material.
Wherein, the inert gas is argon gas or nitrogen, and the preferred temperature of calcining is 750 DEG C -780 DEG C, 4~8h of time.
The present invention also provides a kind of lithium titanate-carbon nano tube compound materials comprising carbon nanotubes and in carbon nanotubes table
Face fabricated in situ and the lithium titanate nano particle for being loaded on carbon nanotubes surface；The grain size of the lithium titanate nano particle is 50
~200nm, the lithium titanate are Li4Ti5O12。
The present invention also provides a kind of lithium ion battery, the negative material in the lithium ion battery is aforementioned arbitrary embodiment party
Lithium titanate-carbon nano tube compound material prepared by method.
In this application, LTO is Li4Ti5O12Abbreviation, refer to lithium titanate；CNTs is the contracting of Carbon nano-tubes
It writes, refers to carbon nanotube；LTO-CNTs is Li4Ti5O12The abbreviation of-CNTs refers to lithium titanate-carbon nano tube compound material.
Lithium titanate-carbon nano tube compound material prepared according to the methods of the invention, synthesis lithium titanate-carbon nanotube are compound
In material, carbon nanotube accounts for the 0.01~10% of gross mass.
Lithium titanate-carbon nano tube compound material prepared according to the methods of the invention, in lithium ion battery negative material
Application.
The present invention preparation method, the advantage is that, the method reaction step simple reaction mild condition, prepare answer
During condensation material, the operation for obtaining gel is not centrifuged, Material cladding uniformity is good, and lithium titanate particle is tiny and divides
Cloth is uniform, and composite material conductive rate is obviously improved.
The technical effects of the invention are that：
(1) in preparation method of the present invention, there are one preprocessing process, i.e., oxidized sour (such as sulphur of property for the carbon nanotube used
Acid or nitric acid etc.) after processing, more polar oxygen-containing groups (such as hydroxyl, carboxyl) are formed in carbon nano tube surface, make reaction
The lithium titanate of middle synthesis can preferably be bonded connection with the polar group of carbon nano tube surface, and be disperseed.
(2) in preparation method of the present invention, using the solvent of low proton ability, such as absolute ethyl alcohol, the prior art is substituted
Basic solvent of the water as reaction environment system, in entire reaction process, due to absolute ethyl alcohol compared to water have it is weaker
Protonation ability reduces the protonation of butyl titanate significantly, keeps the lithium titanate particle granularity of synthesis thinner and grain size point
Cloth is evenly.
(3) preparation method of the invention is during obtaining precursor powder, wherein the carbon nanotube in the first solution exists
In alcoholic solution (such as：Absolute ethyl alcohol makees solvent) through homogenizing, stirring forms the suspension of carbon nanotube, then, the first solution and the
The life reaction of two solution hybrid concurrencies, wherein organic titanium and lithium are continuously generated metatitanic acid lithium dimer during the reaction, and lithium titanate divides
Son is accumulated and is grown up on carbon nanotube suspended particulate, deposited, and obtains solid particle precursor powder.Since liquid-liquid type reacts
System has the characteristics that ensure product uniformity, the in addition uniformity of carbon nano tube suspension particle, so as to get Li4Ti5O12-
The compound uniformity of carbon nano tube compound material is more preferable, the consistency of material more preferably, the conductivity shown i.e. chemical property
It is more excellent.
(4) it when being used as lithium ion battery negative material according to the composite material for preparing of the present invention, shows excellent big
High rate performance and electrochemical cycle stability have high discharge capacity.In preparation method, the addition one side of carbon nanotube is not
Conductive network can be only provided；Lithium titanate grain size can be obviously reduced in the addition of what is more important, another aspect carbon nanotubes,
So that lithium carbonate is in granular form (non-sheet is dendritic), so as to shorten ion transmission distance therefore can in terms of two bigger journey
The electric conductivity of the raising material of degree.When lithium titanate-carbon nano tube compound material of preparation is used for lithium ion battery negative material, electricity
Pond shows higher discharge capacity, good electrochemical cycle stability, disclosure satisfy that high rate charge-discharge demand, has good
Good safety.In charge and discharge process, lithium titanate Li4Ti5O12Li can be changed7Ti5O12, but react both front and back structure cell
Parameter is very close, the characteristic with " zero strain ", therefore can avoid the generation of Li dendrite, has very high safety, is one
The ideal lithium ion battery negative material of kind.
Description of the drawings
Fig. 1 is the flow diagram according to synthetic method preferred embodiment of the present invention.
Fig. 2A is the scanning electron microscope (SEM) photograph of the nanometer LTO prepared by comparative example.
Fig. 2 B are the Li prepared according to the experimental example 3 of synthetic method of the present invention4Ti5O12The scanning electricity of-CNTs composite materials
Mirror figure.
Fig. 3 is the Li prepared according to the experimental example 3 of synthetic method of the present invention4Ti5O12The transmission electron microscope of-CNTs composite materials
Figure.
Fig. 4 is the TEM figures for the lithium titanate-carbon nano tube compound material being prepared using water as solvent.
Fig. 5 is Li prepared by embodiment 34Ti5O12The X-ray diffraction pattern of-CNTs composite materials.
Specific implementation mode
In order to preferably explain the present invention, in order to understand, below in conjunction with the accompanying drawings, by specific implementation mode, to this hair
It is bright to be described in detail.
Scheme provided by the invention includes forerunner's preparation step and calcining step substantially.Wherein forerunner's preparation step is logical
It crosses carbon nanotube, organic titanium source and lithium source being placed in the dicyandiamide solution of absolute alcohol and react, it is compound to obtain lithium titanate-carbon nanotube
The presoma of material；Calcining step calcines presoma, obtains lithium titanate-carbon nano tube compound material.
More specific method is:It takes a certain amount of carbon nanotube to be added to oxidizing acid solution, heats, be condensed back to
Stream is dried to obtain the carbon nanotube of acid processing.It is added aforementioned containing organic titanium source, the nothing of lithium source through the processed carbon nanotube of acid
In water-alcohol solution and through the operation that homogenizes, anhydrous alcohol solution is then subjected to solvent-thermal method reaction, detaches solid particulate matter, is obtained
Precursor powder；Precursor powder is placed in the lower high-temperature heat treatment of inert gas atmosphere protection, obtains target product Li4Ti5O12-
Carbon nano tube compound material.
One preferred embodiment of the synthetic method of the present invention, as shown in Figure 1, including step：
S1：It takes a certain amount of carbon nanotube to be added in oxidizing acid solution, heats, then condensing reflux, it is dry
Obtain the carbon nanotube of acid processing；
S2：The organic titanium source of certain amount of substance is added in nonaqueous liquid alcohol and is configured to the alcoholic solution containing organic titanium, by one
The carbon nano-tube material for determining quality is added in the alcoholic solution of aforementioned organic titanium, and carries out the operation that homogenizes, and obtains the first solution；
Organic titanium source be titanium organic acid or titanium Organic Alcohol, preferably isopropyl titanate, butyl titanate, tetraisopropyl titanate,
Tetraethyl titanate or tetrabutyl titanate；Organic titanium source can be configured to the anhydrous alcohol solution of 0.15~0.2mol/L；Preferably 0.15~
The anhydrous alcohol solution of 0.18mol/L.The operation therein that homogenizes, which can be used, is ultrasonically treated 2h~4h.Wherein carbon nanotube preferably one
The carbon nanotube that kind caliber is 20nm~50nm, and the ratio between the amount of substance (with the substance gauge of Ti) of carbon nanotube and organic titanium source
It is 1:(5~100), preferably 1：(5-30).
S3：The lithium source of certain amount of substance is added in nonaqueous liquid alcohol and is configured to the alcoholic solution containing lithium, obtains the second solution；
Wherein lithium source is that lithium acetate, lithia or lithium hydroxide are configured to 0.3mol/L~0.6mol/L's using absolute alcohol as solvent etc.
Anhydrous alcohol solution, preferred concentration are the anhydrous alcohol solution of 0.4~0.45mol/L.
Wherein, the solvent absolute alcohol that step S2 and step S3 are used may be selected to be ethyl alcohol, propyl alcohol or butanol etc. at normal temperatures
For the alcohol of liquid.
S4：Under strong magnetic stirring, the second solution is added in the first solution, in sealed environment and 120~180 DEG C of temperature
Solvent-thermal method is carried out under the conditions of degree and reacts 16-36h, is detached solid particulate matter, is obtained precursor powder.Preferably, solvent-thermal method
The condition of reaction is sealed environment and temperature at 120 DEG C~140 DEG C, and the reaction time is 20~28 hours.It is added in the second solution
When to the first solution, it need to ensure that the ratio between amount of substance of organic titanium source and lithium source meets 5:4~5:4.2.
S5：Precursor powder is placed in inert gas atmosphere and protects lower 650-850 DEG C of high-temperature heat treatment, obtains target product
LTO-CNTs composite materials.Wherein, it is preferred that inert gas may be selected to be argon gas or nitrogen, nitrogen etc., and high-temperature process temperature is
750 DEG C~780 DEG C, 3~8h of duration.
When the ratio between amount of substance (with the substance gauge of Ti) of carbon nanotube and organic titanium source is 1:When (5-100), most throughout one's life
At product LTO/CNTs composite materials in, the mass percent of carbon nanotube is 0.01%~10%.
It should be noted that the sequence of step S2 and step S3 can exchange in the above implementation steps, can obtain expected
Technique effect.
In addition, carbon nanotube can also be added in the anhydrous alcohol solution containing the lithium sources such as lithium acetate or lithium hydroxide, then
The first solution is obtained after matter processing, and the anhydrous alcohol solution containing organic titanium source is defined as the second solution.That is, carbon nanotube
Both it can be added in the alcoholic solution of lithium source, can also be added in the alcoholic solution of organic titanium, as long as uniform carbon nanotubes can be obtained
Suspension.Pay attention to：In the first solution and the second solution hybrid reaction, in order to make the titanium being continuously generated in reaction process
Sour lithium can load on carbon nanotube suspended particulate, the second solution of not carbon nanotubes should be slowly added dropwise or using compacted
Dynamic pump is added slowly in the first solution of carbon nanotubes suspended particulate, if being otherwise added dropwise in turn, reaction can be caused to start to give birth to
At a large amount of lithium titanates nowhere load and deposit, affect the compound uniformity of lithium titanate-carbon nano-tube material.
In the synthetic method of the present invention, it is more that the used oxidized property low-kappa number of carbon nanotube makes surface have
Oxygen-containing group provides the bonding action with lithium titanate；Using absolute ethyl alcohol as reaction dissolvent system, metatitanic acid four is reduced significantly
The protonation of butyl ester makes product grain grain size reduce, improves the uniformity；Synthesis presoma be in anhydrous alcohol solution while synthesis while
The process loaded on carbon nanotube suspended particulate keeps lithium titanate evenly compound with carbon nanotube, and the consistency of material is more
It is good.
In the synthetic method of the present invention, the addition of carbon nanotube can not only provide three-dimensional conductive network, Er Qie
Two solution are mixed with the first solution when reacting, and the lithium titanate of generation can be attached to the carbon nanotube in carbon nanotube suspension
On particle, carbon nanotube can not only provide conductive network structure, and the particle size of lithium titanate can further be promoted to become
It is small, make grain size of the lithium titanate with very little on the composite material of acquisition, shortens lithium ion transport path, therefore can be in terms of two
Effectively improve composite material conductivity.Lithium-ion electric is used for using lithium titanate/carbon/carbon nano tube composite material prepared by this method
Pond negative material has high discharge capacity, good electrochemical cycle stability, meets high rate charge-discharge demand, is used for lithium
Ion battery cathode material has good safety.
In order to help to understand, and the preparation method and its technique effect further illustrated the present invention, below in conjunction with specific reality
Example, comparative example and the battery assembling experiment as negative electrode material is applied to be described as follows.
Experimental example 1：Synthesis (the titanium source of lithium titanate/carbon/carbon nano tube composite material:Isopropyl titanate)：
(1) carbon nanotube of 0.200g is taken to be added to the mixed solution (V of 50ml concentrated nitric acids and the concentrated sulfuric acidH2SO4：V(HNO3)=
1：1) in, heat treatment, then condensing reflux, freeze-drying obtains the carbon nanotube of acid processing.
(2) 0.05mol isopropyl titanates are added drop-wise to magnetic stirring in the absolute ethyl alcohol of 300mL dropwise and obtain mixed solution
A1, the processed carbon nanotube (caliber 30nm) of above-mentioned acid is then added to above-mentioned A1In solution, it is subsequently placed in high-power ultrasonic
Ultrasonic homogenation handles 3h in instrument, obtains the first solution；
(3) by the CH of 0.0405mol3COOLi·2H2O is dissolved into 100mL absolute ethyl alcohols and obtains B1Solution is (molten for second
Liquid), under strong magnetic stirring, by B1Solution is slowly dropped in the first solution, continues to stir 4h at room temperature；
(4) it is positioned in reaction kettle again, is warming up to 180 DEG C of progress solvent-thermal methods in a sealed meter environment and reacts 20h, it is molten at this time
Solid particulate matter is formed below agent, is then filtered by vacuum, dried, and precursor powder is obtained.
(5) above-mentioned precursor powder is placed in 650C high-temperature heat treatment 7h~8h in the tube furnace under the conditions of nitrogen atmosphere,
Obtain target product LTO-CNTs composite materials.Granular LTO can be observed by electronic scanner microscope and be distributed in CNTs
Network structure in, form uniform composite material.
Experimental example 2：Synthesis (the titanium source of lithium titanate/carbon/carbon nano tube composite material:Tetrabutyl titanate)：
(1) it takes the carbon nanotube of 0.200g to be added in 50ml concentrated sulfuric acid solutions, heats, then condensing reflux, cold
Freeze the carbon nanotube for being dried to obtain acid processing；
(2) by the CH of 0.0398mol3COOLi·2H2O is dissolved into 100mL absolute ethyl alcohols and obtains mixed solution A1, then
The processed carbon nanotube (caliber 20nm) of above-mentioned acid is added to above-mentioned A1In solution, it is subsequently placed in high-power ultrasonic instrument and surpasses
Sound homogenize process 3h, obtains the first solution；
(3) 0.05mol tetrabutyl titanates are added drop-wise to magnetic stirring in 300mL ethyl alcohol dropwise and obtain B1Solution (is second
Solution), under strong magnetic stirring, by B1Solution is slowly dropped in the first solution, continues to stir 2h at room temperature；
(4) it is positioned in reaction kettle again, is warming up to 120C progress solvent-thermal methods in a sealed meter environment and reacts 36h, it is molten at this time
Solid particulate matter is formed below agent, is then filtered by vacuum, dried, and precursor powder is obtained.
(5) above-mentioned precursor powder is placed in 850C high-temperature heat treatment 4h~5h in the tube furnace under the conditions of nitrogen atmosphere,
Obtain target product LTO-CNTs composite materials.Granular LTO can be observed by electronic scanner microscope and be distributed in CNTs
Network structure in, form uniform composite material.
Experimental example 3：Synthesis (the titanium source of lithium titanate/carbon/carbon nano tube composite material:Butyl titanate)：
(1) carbon nanotube of 0.200g is taken to be added to the mixed solution (V of 50ml concentrated nitric acids and the concentrated sulfuric acidH2SO4：V(HNO3)=
1：3) in, heat treatment, then condensing reflux, freeze-drying obtains the carbon nanotube of acid processing.
(2) 17.015g butyl titanates (0.05mol) magnetic stirring in 300mL absolute ethyl alcohols is added drop-wise to dropwise to obtain
Mixed solution A1, the processed carbon nanotube (caliber 20-50nm) of above-mentioned acid is then added to above-mentioned A1In solution, then set
Ultrasonic homogenation handles 2h~3h in high-power ultrasonic instrument, obtains the first solution；
(3) by 4.336g CH3COOLi·2H2O (about 0.04mol), which is dissolved into 100mL absolute ethyl alcohols, obtains B1Solution
(i.e. the second solution), under strong magnetic stirring, by B1Solution is slowly dropped in the first solution, continues to stir 2h at room temperature；
(4) it is positioned in reaction kettle again, is warming up to 150C in a sealed meter environment and carries out solvent-thermal method reaction for 24 hours, it is molten at this time
Solid particulate matter is formed below agent, is then filtered by vacuum, dried, and precursor powder is obtained.
(5) above-mentioned precursor powder is placed in 800C high-temperature heat treatment 4h~5h in the tube furnace under the conditions of nitrogen atmosphere,
Obtain target product LTO-CNTs composite materials.
By product manufactured in the present embodiment using X-ray diffraction spectra instrument test knot, the results are shown in Figure 5, shows as 2
θ=18.37 °, 35.6 °, 43.27 °, 47.38 °, 57.23 °, 62.86 °, 66.09 ° there is strong characteristic peak, indicate carbon nanometer
Pipe surface is covered with crystallization than more completely Li4Ti5O12Particle.The figure can characterize through the embodiment of the present invention 3, can get really
Li4Ti5O12- CNTs composite materials.
Comparative example：The building-up process of nanometer LTO：
17.015g butyl titanates (0.05mol) are added drop-wise to magnetic stirring in 300mL absolute ethyl alcohols dropwise to be mixed
Solution A；
By 4.336g CH3COOLi·2H2O (about 0.04mol), which is dissolved into 100mL absolute ethyl alcohols, obtains B solution, strong
Under power magnetic stirring, B solution is slowly dropped in solution A, continues to stir 2h at room temperature, then seal 150C solvent thermal reactions
24h；Then it is filtered by vacuum, dried, obtain precursor powder.Above-mentioned precursor powder is placed in 800C high temperature in tube furnace
It is heat-treated 4h, obtains product lithium titanate Li4Ti5O12(being abbreviated as LTO).
The LTO of comparative example synthesis and the LTO-CNTs composite materials that embodiment 3 synthesizes are scanned Electronic Speculum and transmission electricity
Mirror is tested, to observe the microscopic appearance of two kinds of materials.Such as the scanning electron microscope (SEM) photograph that Fig. 2A is the nanometer LTO that comparative example synthesizes, Fig. 2 B
It is the Li that embodiment 3 synthesizes4Ti5O12The scanning electron microscope (SEM) photograph of-CNTs composite materials.As can be seen, LTO particles wherein in Fig. 2A
Size is in 300~500nm, and the LTO in Fig. 2 B is uniformly distributed in CNTs three-dimensional net structures, is formed uniform compound
The size of material, wherein LTO particles is about 50~200nm.It is the Li that embodiment 3 synthesizes referring back to Fig. 34Ti5O12/ CNTs is multiple
The transmission electron microscope picture of condensation material, it is equal with nano particle state that the transmission electron microscope of wherein composite material, which more clearly illustrates LTO,
It is attached to the surface of carbon nanotube evenly, LTO nanoparticle sizes are about in 50~200nm.It further can be explained, the present invention is multiple
The synthetic method of condensation material can significantly refine the grain diameter of LTO, make it have more bigger serface, improve composite material
Conductivity.
Fig. 3 and Fig. 4 are subjected to comparison as can be seen that lithium titanate-carbon nanometer that the embodiment of the present invention 3 shown in Fig. 3 synthesizes
The carbon nano tube surface lithium titanate of the nano lithium titanate composite material obtained using water as solvent shown in pipe composite material ratio Fig. 4
The distribution of particle is more uniform.
Assembled battery is tested
The LTO and LTO-CNTs that comparative example and embodiment 3 are synthesized divide as lithium ion battery anode active material
It is not 7 according to mass ratio with acetylene black, binder：2：1 mode mixes, and the configuration of -2 pyrrolidones of Solvents N-methyl is then added dropwise
At electrode slurry, it is prepared into electrode.Then using the electrode being prepared into as cathode, lithium metal as to electrode, single-layer polypropylene
(PP) diaphragm, 1mol/L lithium hexafluoro phosphates (LiPF are used as6) EC/DEC (1:1, v/v) mixed solution is assembled into as electrolyte
Its electrochemistry cycle performance is tested in button cell, the charge and discharge under small multiplying power and big multiplying power respectively, and the results are shown in Table 1.
Small rate charge-discharge experiment：Under the conditions of 1C (1C=175mAh/g) multiplying power, wherein LTO and LTO-CNTs composite woods
The first charge-discharge capacity of material is respectively 173.5mAh/g and 171.9mAh/g, its capacity retention ratio is distinguished after 900 cycles
For 97.2% and 98.7%, illustrate that the composite L TO-CNTs of the method for the present invention synthesis has better electrochemical cycle stability
Property.
High rate charge-discharge is tested：Under the conditions of 5C, the discharge capacity for the first time of LTO-CNTs composite materials is 168.6mAh/g,
Capacity retention ratio after 900 cycles is 98.2%, hence it is evident that higher than the discharge capacity 151.4mAh/g and appearance of LTO under the same terms
Measure conservation rate 94.4%.
Under the conditions of 10C, the discharge capacity for the first time of LTO-CNTs composite materials is 165.9mAh/g, after 900 times recycle
Capacity retention ratio is 97.0%%, hence it is evident that the 153.8mAh/g of discharge capacity for the first time and capacity higher than LTO under the same terms are kept
Rate 91.2% illustrates that LTO-CNTs composite materials prepared by the method for the present invention have excellent high rate charge-discharge stability.
Table 1：LTO and LTO-CNTs is filled respectively as lithium ion battery anode active material under small multiplying power and big multiplying power
The test result of discharge test
It can be seen that lithium titanate-carbon composite material particle prepared by the method for the present invention is small, and even particle size distribution, the material
Show excellent big high rate performance and cycle performance when as negative electrode of lithium ion battery, thus the material high power type lithium from
It is with a wide range of applications in sub- battery.
The preparation method of the present invention takes full advantage of the effect of carbon nanotube energy micronized particles and provides excellent three-dimensional and leads
Electric network has synthesized compound uniform LTO-CNTs composite materials using the method for fabricated in situ LTO-CNTs composite materials,
The size of middle LTO nano particles is significantly less than LTO particle sizes pure under the same terms, which is used for lithium ion battery
Negative material shows excellent electrochemical cycle stability and good high rate charge-discharge performance, and preparation method is simple, easily
In industrialized production.
Claims (10)
1. a kind of preparation method of lithium titanate-carbon nano tube compound material, which is characterized in that including：
Forerunner's preparation step：Carbon nanotube, organic titanium source and lithium source are placed in the dicyandiamide solution of absolute alcohol and reacted, institute is obtained
State the presoma of lithium titanate-carbon nano tube compound material；
Calcining step：The presoma is calcined, the lithium titanate-carbon nano tube compound material is obtained.
2. preparation method according to claim 1, which is characterized in that forerunner's preparation step includes：
The organic titanium source of certain amount of substance is added in absolute alcohol and is configured to the anhydrous alcohol solution containing organic titanium, by certain amount of substance
Lithium source be added absolute alcohol in be configured to the anhydrous alcohol solution containing lithium；
By the carbon nanotube of certain mass be added in one of aforementioned two kinds of solution and the operation that homogenizes to obtain first molten
Liquid, then another kind is defined as the second solution in aforementioned two kinds of solution；
Second solution is added in first solution, and the amount of substance ratio of titanium and lithium in mixed system is made to be 5:4~
5:4.2, after being heated to 120~180 DEG C of reaction 16-36h in a sealed meter environment, solid particulate matter is isolated, the metatitanic acid is obtained
The presoma of lithium-carbon nano tube compound material.
3. preparation method according to claim 1 or 2, which is characterized in that the absolute alcohol is the alcohol being in a liquid state under room temperature.
4. preparation method according to claim 3, which is characterized in that the absolute alcohol is selected from least one of following：
Ethyl alcohol, propyl alcohol and butanol.
5. preparation method according to claim 1 or 2, which is characterized in that the carbon nanotube is the processing of oxidized property acid
Carbon nanotube afterwards.
6. preparation method according to claim 5, which is characterized in that the oxidizing acid be sulfuric acid, nitric acid or sulfuric acid with
The mixture of nitric acid.
7. preparation method according to claim 6, which is characterized in that the oxidizing acid, which is handled, is：Take a certain amount of carbon
Nanotube is added in the solution of oxidizing acid, is heated to reflux a period of time, and the carbon nanotube of acid processing is dried to obtain after filtering.
8. preparation method according to claim 1 or 2, which is characterized in that the calcining step is：By the lithium titanate-
The presoma of carbon nano tube compound material is placed in inert atmosphere, and is calcined at 650-850 DEG C, and Li is obtained4Ti5O12Carbon
Nanometer tube composite materials.
9. a kind of lithium titanate-carbon nano tube compound material prepared according to any preparation methods of claim 1-8, feature exist
In, including：Carbon nanotubes and the lithium titanate nanometer that carbon nanotubes surface is synthesized and be loaded in carbon nanotubes surface in situ
The grain size of grain, the lithium titanate nano particle is 50~200nm, and the lithium titanate is Li4Ti5O12。
10. a kind of lithium ion battery, which is characterized in that the negative material in the lithium ion battery is described in claim 9
Lithium titanate-carbon nano tube compound material.
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| CN110299516A (en) * | 2019-06-10 | 2019-10-01 | 天津大学 | The preparation method of carbon nano pipe array load lithium titanate flexible electrode material |
| CN110459770A (en) * | 2019-07-31 | 2019-11-15 | 桑顿新能源科技(长沙)有限公司 | A kind of lithium titanate anode material, preparation method, cathode pole piece and lithium ion battery |
| CN111799435A (en) * | 2020-05-27 | 2020-10-20 | 广西华政新能源科技有限公司 | Energy storage lithium ion battery nano electrode material |
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| CN106848251A (en) * | 2017-03-15 | 2017-06-13 | 北京朗盛特耐科技有限公司 | A kind of preparation method of CNT lithium titanate composite anode material |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110299516A (en) * | 2019-06-10 | 2019-10-01 | 天津大学 | The preparation method of carbon nano pipe array load lithium titanate flexible electrode material |
| CN110299516B (en) * | 2019-06-10 | 2022-05-10 | 天津大学 | Preparation method of carbon nanotube array loaded lithium titanate flexible electrode material |
| CN110459770A (en) * | 2019-07-31 | 2019-11-15 | 桑顿新能源科技(长沙)有限公司 | A kind of lithium titanate anode material, preparation method, cathode pole piece and lithium ion battery |
| CN111799435A (en) * | 2020-05-27 | 2020-10-20 | 广西华政新能源科技有限公司 | Energy storage lithium ion battery nano electrode material |
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