CN102496707A - Preparation method of nano-grade-carbon-clad spinel lithium titanate battery cathode material - Google Patents
Preparation method of nano-grade-carbon-clad spinel lithium titanate battery cathode material Download PDFInfo
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Abstract
The invention discloses a preparation method of a nano-grade-carbon-clad spinel lithium titanate battery cathode material. The method comprises steps that: titanium dioxide and a lithium source are placed in a dispersant; the mixture is uniformly mixed, and is dried by baking; the dried mixture is pre-roasted for 2-36h under a temperature of 400-800 DEG C in a first atmosphere; the mixture is naturally cooled to room temperature, such that an intermediate product is obtained; the obtained intermediate product and a carbon source are placed in a dispersant; the mixture is uniformly mixed, and is dried by baking; the dried mixture of the dried intermediate product, the carbon source and the dispersant is subject to secondary roasting for 2-36h under a temperature of 700-950 DEG C in second first atmosphere; the mixture is naturally cooled to room temperature, such that nano-grade-carbon-clad spinel lithium titanate is obtained. According to the invention, with the preparation method of the nano-grade-carbon-clad spinel lithium titanate battery cathode material, a lithium titanate cathode material with a nano-grade size, uniform particle morphology, and high purity is obtained. Also, the conductivity of the lithium titanate cathode material is greatly improved.
Description
Technical field
The present invention relates to the battery material technical field, particularly relate to a kind of preparation method of nano-sized carbon coating spinelle lithium titanate cell negative electrode material.
Background technology
In recent years, the output of countries in the world automobile is along with the expanding economy sharp increase, but the aggravation of the exhaustion of the intensification of global energy crisis, petroleum resources and environmental pollution makes automobile industry be faced with the problem of a sternness: energy-conservation and reduction of discharging.Electric automobile is owing to low energy consumption, the pollution-free focus that becomes concern.
Lithium ion battery is because operating voltage is high, and energy density is high, and the little and environmentally safe of self discharge is applied to electric motor car and most possibly substitute traditional lead-acid battery and Ni-MH battery.But what traditional lithium ion battery used is graphite cathode, and the ability of its fast charging and discharging is difficult to reach the requirement of electric motor car; In addition, the embedding lithium current potential of carbon negative pole filling the very possible lithium of analysing in the process soon, produces safety problem near the reduction potential of lithium metal; And cycle life is limited.Above issues limit the application of lithium ion battery in electric motor car.
At present, the appearance of spinel lithium titanate negative material not only makes the cycle life of lithium ion battery significantly improve, and has also improved the ability of the fast charging and discharging of lithium ion battery, and has eliminated owing to analyse the potential safety hazard that lithium brings.These advantages are by the decision of the characteristics of spinel lithium titanate: 1, spinel lithium titanate structure and change in volume in charge and discharge process is very little, is a kind of zero strain material, thereby has excellent cycle performance; 2, the lithium ion diffusion coefficient of lithium titanate material is high, than the high one magnitude of graphite cathode, thereby has stronger fast charging and discharging ability; 3, embedding lithium current potential is 1.5V, is higher than the deposition potential of lithium metal far away, avoids producing dendrite, has eliminated potential safety hazard; 4, the charge and discharge platform of lithium titanate is very smooth, when discharging and recharging end, tangible voltage jump is arranged, and can play discharging and recharging indicative function; 5, has the good low-temperature discharge performance.These characteristics of spinel lithium titanate all make lithium ion battery become desirable electric vehicle electrical source of power.
Though lithium titanate is because the lithium ion diffusion coefficient is high, thereby have stronger fast charging and discharging ability,, extremely low conductivity makes that its electric conductivity is very poor, becomes one of bottleneck of its application to a certain extent.
At present, in order to solve the low problem of spinel lithium titanate negative material conductivity, the method that is adopted has three kinds, and first kind is the preparation nano lithium titanate, reaches shortening lithium ion the evolving path through reducing particle diameter, improves the purpose of conductivity; Second method is: carbon coats.Through coating carbon-coating, improve the electric conductivity of material at the lithium titanate particle surface; The third method is for mixing.
The synthetic method of spinel lithium titanate also has a lot, and solid phase method and sol-gal process are arranged usually.Wherein, sol-gal process can make the raw material of synthetic lithium titanate realize the mixing of atom level, prepares the better conductivity nano lithium titanate; But, its complicated process of preparation, the cycle is long; Add a large amount of organic solvents in the process; Cost is higher, and organic substance a large amount of carbon dioxide of meeting generation in roasting process, is difficult to large-scale industrial production.
And the technology of solid phase method is simple, is fit to large-scale production, still, because solid phase method causes the particle inhomogeneous growth easily in high-temperature calcination process, and forms bigger particle, has reduced the electric conductivity of material.
In addition, in order to produce the spinel lithium titanate negative material, existing a kind of method is that lithium source, titanium source and carbon source are mixed together, and then high temperature (650 ℃-900 ℃) carries out roasting under inert gas shielding.The synthetic material of this method in roasting process because the interference of carbon source is arranged; Though suppressed growing up of lithium titanate particle to a certain extent; But it has also hindered fully contacting of titanium source and lithium source simultaneously, generate the more material of dephasign easily, and granular size is inhomogeneous.
Therefore; Press for a kind of method of developing at present; It can be through simple technology; Prepare have nano-scale, granule-morphology is even, purity is high lithium titanate anode material, make the electric conductivity of raising lithium titanate anode material by a relatively large margin, and be suitable for the production application of scale.
Summary of the invention
In view of this, the purpose of this invention is to provide a kind of preparation method of nano-sized carbon coating spinelle lithium titanate cell negative electrode material, it can be through suppressing the undue growth of particle in the roasting process; Through simple technology; Prepare have nano-scale, granule-morphology is even, purity is high lithium titanate anode material, make lithium titanate anode material have high specific capacity, good high rate performance and cycle performance; Raising by a relatively large margin the electric conductivity of lithium titanate anode material; And be suitable for the production application of scale, help improving the market application foreground of battery production producer product, be of great practical significance.
For this reason, the invention provides a kind of preparation method of nano-sized carbon coating spinelle lithium titanate cell negative electrode material, may further comprise the steps:
The first step: titanium dioxide and lithium source are put in the dispersant, mixed through stirring then, then oven dry;
Second step: the mixture after will dry with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours, naturally cools to room temperature then under first atmosphere, the acquisition intermediate product;
The 3rd step: intermediate product that is obtained and carbon source are put in the dispersant, mixed through stirring then, then oven dry;
The 4th step: the mixture of the intermediate product after will drying, carbon source and dispersant carried out after baking 2 ~ 36 hours with 700 ~ 950 ℃ temperature under second atmosphere, naturally cool to room temperature then, finally obtained nano-sized carbon coating spinelle lithium titanate.
Wherein, said titanium dioxide is the titanium dioxide of Detitanium-ore-type, and the particle size of said titanium dioxide is for being less than or equal to 600nm, and the specific area of said titanium dioxide is 10 ~ 500m
2/ g.
Wherein, the particle size of said titanium dioxide is 5 ~ 300nm, and the specific area of said titanium dioxide is 100-300m
2/ g.
Wherein, said lithium source comprises at least a in lithium carbonate, lithium nitrate and the lithium hydroxide;
Said dispersant comprises at least a in water, ethanol or the acetone;
Said carbon source comprises at least a in glucose, sucrose and the starch.
Wherein, the condition that should meet of the ratio between said titanium dioxide and the lithium source is: the mol ratio between the Ti:Li is 1: (0.8-0.88).
Wherein, the mol ratio between the said Ti:Li is 1: (0.824-0.848).
Wherein, the raw material of said titanium dioxide and lithium source composition and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3);
Said carbon source accounts for the 1%-20% of said intermediate product and carbon source total weight;
The raw material that said intermediate product and carbon source are formed and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3).
Wherein, the raw material of said titanium dioxide and lithium source composition and the weight ratio of dispersant are (1 ~ 1.5): (1 ~ 2);
Said carbon source accounts for the 3%-6% of said intermediate product and carbon source total weight;
The raw material that said intermediate product and carbon source are formed and the weight ratio of dispersant are (1 ~ 1.5): (1 ~ 2).
Wherein, said second step is specially: the mixture of oven dry is positioned in the crucible, then crucible is put in the Muffle furnace, then under first atmosphere with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours, naturally cool to room temperature then, the acquisition intermediate product;
Said the 4th step is specially: the mixture of the intermediate product after will drying, carbon source and dispersant is positioned in the crucible; Then crucible is put in the atmosphere furnace; Under second atmosphere, carried out after baking 2 ~ 36 hours then with 700 ~ 950 ℃ temperature; Naturally cool to room temperature then, finally obtain nano-sized carbon coating spinelle lithium titanate.
Wherein, said first atmosphere is air atmosphere, inert gas atmosphere or reducing atmosphere, and said second atmosphere is inert gas atmosphere or reducing atmosphere.
Visible by above technical scheme provided by the invention; Compared with prior art, the invention provides a kind of preparation method of nano-sized carbon coating spinelle lithium titanate cell negative electrode material, it can be through suppressing the undue growth of particle in the roasting process; Through simple technology; Prepare have nano-scale, granule-morphology is even, purity is high lithium titanate anode material, make lithium titanate anode material have high specific capacity, good high rate performance and cycle performance; Raising by a relatively large margin the electric conductivity of lithium titanate anode material; And be suitable for the production application of scale, help improving the market application foreground of battery production producer product, be of great practical significance.
Description of drawings
Fig. 6 18650 cycle performance of battery
Fig. 1 is electronic scanning video picture (SEM) figure of the preparation method embodiment 2 prepared lithium titanate anode materials that obtain of a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material provided by the invention;
Fig. 2 is electronic scanning video picture (SEM) figure of preparation method's comparative example 1 prepared lithium titanate anode material that obtains of a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material of prior art;
Fig. 3 is electronic scanning video picture (SEM) figure of preparation method's comparative example 2 prepared lithium titanate anode materials that obtain of a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material of prior art;
Fig. 4 is the preparation method embodiment 2 prepared lithium titanate anode materials that obtain of a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material provided by the invention and X-ray diffraction (XRD) figure of the prior art comparative example 3 prepared lithium titanate anode materials that obtain;
The first charge-discharge curve synoptic diagram of the buckle type lithium-ion battery that Fig. 5 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation;
The cycle performance sketch map of the buckle type lithium-ion battery that Fig. 6 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation;
The first charge-discharge efficiency test result tabular drawing of the buckle type lithium-ion battery that Fig. 7 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation;
The cycle performance test result tabular drawing of the buckle type lithium-ion battery that Fig. 8 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation;
The multiplying power discharging property test result tabular drawing of the buckle type lithium-ion battery that Fig. 9 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation;
The multiplying power charging performance test result tabular drawing of the buckle type lithium-ion battery that Figure 10 is produced for the nano-sized carbon coating spinelle lithium titanate cell negative electrode material of utilization method provided by the invention preparation.
Embodiment
In order to make those skilled in the art person understand the present invention program better, the present invention is done further detailed description below in conjunction with accompanying drawing and execution mode.
The invention provides a kind of preparation method of nano-sized carbon coating spinelle lithium titanate cell negative electrode material, may further comprise the steps:
The first step: at first titanium dioxide and lithium source are put in the dispersant, mixed through stirring then, then oven dry;
Second step: the mixture after will dry with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours, naturally cools to room temperature (said room temperature for example is 15 ~ 25 ℃) then under first atmosphere, the acquisition intermediate product;
The 3rd step: intermediate product that is obtained and carbon source are put in the dispersant, mixed through stirring then, then oven dry;
The 4th step: the mixture of the intermediate product after will drying, carbon source and dispersant carried out after baking 2 ~ 36 hours with 700 ~ 950 ℃ temperature under second atmosphere; Naturally cool to room temperature (said room temperature for example is 15 ~ 25 ℃) then, finally obtain nano-sized carbon coating spinelle lithium titanate (Li
4Ti
5O
12), this nano-sized carbon coating spinelle lithium titanate can be used as the negative material of lithium ion battery.
Need to prove that the above-mentioned nano-sized carbon coating spinelle lithium titanate cell negative electrode material of the present invention preparation specifically can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
In the preparation process of concrete battery cathode sheet; Above-mentioned nano-sized carbon coating spinelle lithium titanate anode material is as the major ingredient of cathode size; Nano-sized carbon coating spinelle lithium titanate anode material (cathode size major ingredient) and binding agent, conductive agent, solvent etc. are mixed, stir, obtain cathode size; Then cathode size is coated on the negative current collector (like Copper Foil) equably; Dry then, make cathode size on the negative pole currect collecting surface, form one deck negative electrode active material layer fully, thereby prepare the negative plate of lithium ion battery.
Need to prove that in preparation battery cathode sheet process, the binding agent of said negative electrode active material for example can be for including polytetrafluoroethylene, gathering at least a in inclined to one side tetrafluoroethene, phenolic resins, polyvinyl alcohol and the polyvinylpyrrolidone; Said conductive agent can include at least a in carbon black, CNT, acetylene black, electrically conductive graphite and the Graphene; The solvent of said negative electrode active material includes N-crassitude ketone solvent.
In the preparation method of nano-sized carbon coating spinelle lithium titanate anode material provided by the invention, said titanium dioxide can be the titanium dioxide of unformed, Detitanium-ore-type or rutile-type, is preferably the titanium dioxide of Detitanium-ore-type; The particle size of said titanium dioxide is D
50≤600nm, the particle size optimum of said titanium dioxide is 5 ~ 300nm; The specific area of said titanium dioxide is 10 ~ 500m
2/ g is preferably 100 ~ 300m
2/ g.
In the present invention, said lithium source can be the hydroxide of inorganic lithium salt, organic lithium salt or lithium.For example, said inorganic lithium salt can be lithium carbonate, lithium nitrate and person's lithium chloride; Organic lithium salt can be lithium acetate and lithium oxalate; The hydroxide of said lithium can be lithium hydroxide.
On concrete the realization, said lithium source is preferably and comprises at least a in lithium carbonate, lithium nitrate and the lithium hydroxide.
In the first step, the condition that the ratio between said titanium dioxide and the lithium source should meet is: the mol ratio between the Ti:Li is 1: (0.8-0.88), the mol ratio between the said Ti:Li is preferably 1: (0.824-0.848).
In the first step, by said titanium dioxide and lithium source constitutive material dispersing and mixing in dispersant, the raw material that said titanium dioxide and lithium source are formed and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3) is preferably (1 ~ 1.5): (1 ~ 2).
In the present invention, the said first step and the dispersant in the 3rd step can be preferably ethanol for comprising at least a in water, ethanol or the acetone.
In the 3rd step of the present invention, said carbon source can be for simple substance carbon or at high temperature can be cracked into the organic substance of carbon.For example, said simple substance carbon can be graphite and active carbon etc.; The organic substance that high temperature can be cracked into carbon down can be carbohydrate, phenolic resins and polyethylene glycol.
On concrete the realization, said carbon source is preferably and comprises at least a in glucose, sucrose and the starch.
In the 3rd step of the present invention, said carbon source accounts for the 1%-20% of said intermediate product and carbon source total weight, is preferably 3%-6%.
In the 3rd step of the present invention, said intermediate product and carbon source dispersing and mixing in dispersant, the raw material that said intermediate product and carbon source are formed and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3) is preferably (1 ~ 1.5): (1 ~ 2).
In the present invention; For titanium dioxide, lithium source and dispersant are evenly mixed; The said first step is specially: titanium dioxide, lithium source and dispersant put in the container of mixing and ball milling, and then with 100～1000 rev/mins rotating speed ball milling 1～36 hour, oven dry then; On concrete the realization, be preferably with 200 ~ 500 rev/mins rotating speed ball milling 3 ~ 16 hours.
Certainly; Need to prove that the method that titanium dioxide, lithium source and dispersant are evenly mixed can be a conventional method arbitrarily, for example stir, ball milling; The equipment that uses can be for conventional dispersing and mixing equipment, like homogenizer, ball mill, sand mill.
In the present invention; The container of said mixing and ball milling can be corundum ball grinder, agate jar, polyurethane ball grinder, nylon ball grinder or tungsten carbide ball milling jar, and the abrading-ball that the container of said mixing and ball milling has can be zirconia ball, corundum ball, agate ball or polyurethane ball.Be used for the ball mill that the container in said mixing and ball milling uses and be preferably planetary ball mill.
In the present invention; For intermediate product, carbon source and dispersant are evenly mixed; Said the 3rd step is specially: intermediate product, carbon source and dispersant put in the container of mixing and ball milling, and then with 100～1000 rev/mins rotating speed ball milling 1～36 hour, oven dry then; On concrete the realization, be preferably with 200 ~ 500 rev/mins rotating speed ball milling 3 ~ 16 hours.
Certainly; Need to prove that the method that intermediate product, carbon source and dispersant are evenly mixed can be a conventional method arbitrarily, for example stir, ball milling; The equipment that uses can be for conventional dispersing and mixing equipment, like homogenizer, ball mill, sand mill.
In second step of the present invention; Be specially: the mixture of oven dry is positioned in the crucible, then crucible is put in the Muffle furnace (being resistance furnace), then under first atmosphere with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours; Naturally cool to room temperature then, obtain intermediate product.
In the 4th step of the present invention; Be specially: the mixture of the intermediate product after will drying, carbon source and dispersant is positioned in the crucible; Then crucible is put in the atmosphere furnace; Under second atmosphere, carried out after baking 2 ~ 36 hours then, naturally cool to room temperature then, finally obtain nano-sized carbon coating spinelle lithium titanate with 700 ~ 950 ℃ temperature.
In the present invention, the said first step and the drying operation in the 3rd step can be oven dry or spraying oven dry in vacuum drying, the air, on concrete the realization, can for: be not less than 150
OCTemperature under vacuumize 12 ~ 24 hours.
In the present invention, said first atmosphere can be air atmosphere, inert gas atmosphere or reducing atmosphere, for example is hydrogen or argon gas atmosphere.Said second atmosphere can be inert gas atmosphere or reducing atmosphere, for example is nitrogen, hydrogen or argon gas atmosphere.
Through specific embodiment the present invention is further specified below.
Embodiment 1: at first take by weighing particle size D
50For 300nm, specific area are that BET is 100m
2The titanium dioxide 1000g of/g is placed in the ball grinder with the lithium carbonate of 380g and the ethanol of 2000g then, and on planetary ball mill with 400rpm (rev/min) rotating speed ball milling 8 hours, take out oven dry then.The mixture of oven dry is positioned in the crucible, puts into Muffle furnace, be warming up to 750 ℃ and carry out preroast, and be incubated 6 hours, naturally cool to room temperature then, obtain intermediate product A.
Take by weighing intermediate product A, glucose 165g and the ethanol 1750g of 1000g, be positioned in the ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible; Put into atmosphere furnace; Under nitrogen protection, be warming up to 800 ℃ and carry out after baking, and be incubated 6 hours, naturally cool to room temperature; Finally obtain nano-sized carbon and coat lithium titanate, this nano-sized carbon coats lithium titanate and can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
Embodiment 2: at first take by weighing particle size D
50For 50nm, specific area BET are 200m
2The titanium dioxide 1000g of/g is positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 8 hours, takes out oven dry then.The mixture of oven dry is positioned in the crucible, then crucible is put in the Muffle furnace, be warming up to 700 ℃, and be incubated 4 hours, naturally cool to room temperature then, obtain intermediate product B.
Take by weighing intermediate product B, glucose 165g and the ethanol 1750g of 1000g, be positioned in the ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible; Put into atmosphere furnace then, under nitrogen protection, be warming up to 750 ℃, be incubated 10 hours; Naturally cool to room temperature; Finally obtain nano-sized carbon and coat lithium titanate, referring to Fig. 1 and shown in Figure 4, this nano-sized carbon coats lithium titanate and can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
Embodiment 3: at first taking by weighing particle size D50 is that 25nm, specific area BET are the titanium dioxide 1000g of 300m2/g; Be positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then; On planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 8 hours.The mixture of oven dry is placed crucible, put in the Muffle furnace, be warming up to 600 ℃, and be incubated 6 hours, naturally cool to room temperature, obtain intermediate product C.
Take by weighing intermediate product C, glucose 165g and the ethanol 1750g of 1000g, place ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible; Put into atmosphere furnace then; Under nitrogen protection, be warming up to 850 ℃, be incubated 4 hours, naturally cool to room temperature; Obtain nano-sized carbon and coat lithium titanate, this nano-sized carbon coats lithium titanate and can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
Embodiment 4: at first take by weighing particle size D
50For 50nm, specific area BET are 200m
2The titanium dioxide 1000g of/g is positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 4 hours, takes out oven dry then.The mixture of oven dry is placed crucible, put into Muffle furnace, be warming up to 700 ℃, and be incubated 4 hours, naturally cool to room temperature, obtain intermediate product D.
Take by weighing product D, glucose 300g and the water 1750g of 1000g, place ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible; Put into atmosphere furnace then; Under nitrogen protection, be warming up to 800 ℃, and be incubated 6 hours, naturally cool to room temperature; Obtain nano-sized carbon and coat lithium titanate, this nano-sized carbon coats lithium titanate and can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
Embodiment 5: at first take by weighing particle size D
50For 50nm, specific area BET are 200m
2The titanium dioxide 1000g of/g is positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 4 hours, takes out oven dry then.The mixture of oven dry is placed crucible, put into Muffle furnace, be warming up to 700 ℃, be incubated 4 hours, naturally cool to room temperature, obtain intermediate product E.
Take by weighing intermediate product E, sucrose 165g and the water 1750g of 1000g, place ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible; Put into atmosphere furnace; Under nitrogen protection, be warming up to 800 ℃, be incubated 6 hours, naturally cool to room temperature; Obtain nano-sized carbon and coat lithium titanate, this nano-sized carbon coats lithium titanate and can be used as coated negative electrode active material on the negative current collector of anode plate for lithium ionic cell.
Comparative Examples 1: at first take by weighing particle size D
50Be that 1 μ m, specific area BET are 20m
2The 1000g of/g titanium dioxide is positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 8 hours, takes out oven dry then.The mixture of oven dry is placed crucible, put into Muffle furnace, be warming up to 750 ℃, be incubated 6 hours, naturally cool to room temperature, obtain intermediate product F.
Take by weighing product 1000g F, glucose 165g and ethanol 1750g, place ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible, put into atmosphere furnace, under nitrogen protection, be warming up to 800 ℃, be incubated 6 hours, naturally cool to room temperature, obtain carbon and coat lithium titanate, referring to shown in Figure 2.
Comparative Examples 2: at first take by weighing particle size D
50Be 25nm, specific area BET=300m
2The titanium dioxide 1000g of/g is positioned in the ball grinder with 380g lithium carbonate and 2000g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 8 hours, takes out oven dry then.The mixture of oven dry is placed crucible, put into Muffle furnace, be warming up to 900 ℃, be incubated 4 hours, naturally cool to room temperature, obtain intermediate product G.
Take by weighing intermediate product G, glucose 165g and the ethanol 1750g of 1000g, place ball grinder, on planetary ball mill,, take out oven dry then with the rotating speed ball milling of 400rpm 4 hours.The mixture of oven dry is placed crucible, put into atmosphere furnace, under nitrogen protection, be warming up to 850 ℃, be incubated 4 hours, naturally cool to room temperature, obtain carbon and coat lithium titanate, referring to shown in Figure 3.
Comparative Examples 3: at first take by weighing particle size D
50Be 25nm, specific area BET=300m
2The titanium dioxide 1000g of/g is positioned in the ball grinder with 380g lithium carbonate, glucose 189g and 2350g ethanol then, on planetary ball mill, with the rotating speed ball milling of 400rpm 6 hours, takes out oven dry then.The mixture of oven dry is placed crucible, put into atmosphere furnace, under nitrogen protection, be warming up to 850 ℃, be incubated 10 hours, naturally cool to room temperature, obtain carbon and coat lithium titanate.
Use battery with button cell as experiment, the above-mentioned carbon for preparing is coated lithium titanate as the negative electrode active material on this battery cathode sheet, carry out the preparation of battery.
Need to prove; The capacity of the test material of said button cell is specially: the electrode ratio of button cell is: the weight ratio=90:5:5 between LTO (lithium titanate, it is as the negative electrode active material on the negative plate collector), SP (carbon black conductive agent) and the Kynoar (PVDF, it is as binding agent); Battery be metal lithium sheet to electrode; Adopt the Celgard2320 type barrier film of the U.S., electrolyte is dissolved in the organic solvent of being made up of dimethyl carbonate DMC, methyl ethyl carbonate EMC and vinyl acetate EC, wherein by the lithium hexafluoro phosphate (LiPF6) as electrolytic salt; The molar concentration of said lithium hexafluoro phosphate is 1mol/L; Percentage by weight between said DMC, EMC and the EC is: 1:1:1, charging and discharging currents are 0.05C, and voltage is 1V-3V.
In the present invention, the concrete preparation method of button cell is following:
At first; Lithium titanate, conductive agent and the N-methyl pyrrolidone (NMP) of the foregoing description and the prepared acquisition of the comparative example weight ratio according to 90:6:4 is mixed, be dissolved in then in the Kynoar (PVDF), obtain having mobile cathode size; Cathode size is coated on the negative current collector (like Copper Foil) equably; Oven dry then makes cathode size on the negative pole currect collecting surface, form one deck negative electrode active material layer fully, obtains negative plate.
Then; LiMn2O4, conductive agent and Kynoar (PVDF) weight ratio according to 90:6:4 is mixed, be dissolved in then in the Kynoar (PVDF), obtain having mobile anode sizing agent; Anode sizing agent is coated on the plus plate current-collecting body (like aluminium foil) equably; Oven dry then makes anode sizing agent on the anode collection surface, form one deck positive electrode active material layer fully, obtains positive plate.
At last; The electrolyte of configuration button cell; Make that the molar concentration of lithium hexafluoro phosphate (LiPF6) is 1mol/L in the electrolyte; And the organic solvent in the electrolyte is dimethyl carbonate DMC, methyl ethyl carbonate EMC and vinyl acetate EC, and the weight ratio between said dimethyl carbonate DMC, methyl ethyl carbonate EMC and the vinyl acetate EC is 1:1:1.The membrane thicknesses of said button cell is 20 μ.
The present invention explains the performance of the nano-sized carbon coating spinelle lithium titanate that the present invention prepares through multinomial test.
1, first charge-discharge efficiency: with the battery that makes with the 0.2C constant current charge to 3V, charge to 0.02C.And then with the 0.2C constant-current discharge to 1V.First charge-discharge efficiency %=discharge capacity * 100/ charging capacity, test result is referring to Fig. 5 and shown in Figure 7.
2, battery capacity: with the battery that makes with the 1C constant current charge to 3V, charge to 0.02C.And then with the 1C constant-current discharge to 1V.This discharge capacity is a battery capacity.
3, cycle performance: with the battery that makes with the 5C constant current charge to 3V, charge to 0.02C.And then with the 5C constant-current discharge to 1V.Repeat 1000 times.The discharge capacity * 100/ that circulation volume sustainment rate %=is the 1000th time is discharge capacity for the first time, and test result is referring to Fig. 6 and shown in Figure 8.
4, multiplying power discharging property: with the battery that makes with the 1C constant current charge to 3V, charge to 0.02C.Then respectively again with 0.5C, 1C, 5C, 10C, 15C, 20C, 25C, 30C constant-current discharge to 1V.Multiplying power discharging property %=nC capacity * 100/0.5C capacity, test result is referring to shown in Figure 9.
5, multiplying power charging performance: with the battery that makes respectively with 1C, 5C, 8C, 10C, 15C, 20C constant current charge to 3V, charge to 0.02C.Then with the 1C constant-current discharge to 1V.Multiplying power charging performance %=constant-current phase capacity * 100/ battery capacity, test result is referring to shown in Figure 10.
From Fig. 1 to Figure 10, can find out; The present invention is through earlier carry out pre-burning to precursor at low temperatures, and thorough roasting has at high temperature again improved the purity of lithium titanate material; Reduced particle size; Improve the starting efficiency of battery, improved cycle performance, improved the ability of material high current charge-discharge.
The present invention is improvements over the prior art; Effectively suppressed the undue growth of particle in the roasting process, synthesized through simple technology and have nano-scale, granule-morphology is even; The carbon that purity is high coats lithium titanate composite material; Have high specific capacity, good high rate performance and cycle performance are fit to large-scale production.
Can know by above test result; Preparation method for a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material provided by the invention; It has effectively controlled growing up of crystal grain through following approach: the titanium dioxide that 1, adopts nanoscale and have a certain specific surface area is as presoma; Reduce synthesis temperature and time, synthesized nano material; 2, presoma is carried out preroast at low temperatures earlier, prevent that the lithium titanate particle from growing up; 3, add carbon source during high-temperature roasting, guarantee to stop particle at high temperature further to be grown up under the good situation of crystal growth.
Method of the present invention reduces dephasign through following approach, improves crystal structure: 1, low temperature preroast lithium titanate material that formation purity is high earlier or lithium titanate and titanium dioxide, Li
2TiO
3Mixture, it is insufficient with contacting of lithium source and form dephasign to prevent to add in advance titanium dioxide that carbon source causes; 2, high-temperature roasting impels crystal structure further perfect after the later stage adding carbon source.
The spinel lithium titanate material that the present invention synthesizes has nano-scale (D50 < 400nm), the granule-morphology homogeneous, and purity is high, has high specific capacity, good high rate performance and cycle performance, and technology is simple, is easy to industrialization.
Therefore, compared with prior art, the preparation method of a kind of nano-sized carbon coating spinelle lithium titanate cell negative electrode material provided by the invention; It can be through suppressing the undue growth of particle in the roasting process, through simple technology, prepare have nano-scale, granule-morphology is even, purity is high lithium titanate anode material; Make lithium titanate anode material have high specific capacity; Good high rate performance and cycle performance, raising by a relatively large margin the electric conductivity of lithium titanate anode material, and be suitable for the production application of scale; Help improving the market application foreground of battery production producer product, be of great practical significance.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and retouching, these improvement and retouching also should be regarded as protection scope of the present invention.
Claims (10)
1. the preparation method of a nano-sized carbon coating spinelle lithium titanate cell negative electrode material is characterized in that, may further comprise the steps:
The first step: titanium dioxide and lithium source are put in the dispersant, mixed through stirring then, then oven dry;
Second step: the mixture after will dry with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours, naturally cools to room temperature then under first atmosphere, the acquisition intermediate product;
The 3rd step: intermediate product that is obtained and carbon source are put in the dispersant, mixed through stirring then, then oven dry;
The 4th step: the mixture of the intermediate product after will drying, carbon source and dispersant carried out after baking 2 ~ 36 hours with 700 ~ 950 ℃ temperature under second atmosphere, naturally cool to room temperature then, finally obtained nano-sized carbon coating spinelle lithium titanate.
2. preparation method as claimed in claim 1 is characterized in that, said titanium dioxide is the titanium dioxide of Detitanium-ore-type, and the particle size of said titanium dioxide is for being less than or equal to 600nm, and the specific area of said titanium dioxide is 10 ~ 500m
2/ g.
3. preparation method as claimed in claim 2 is characterized in that, the particle size of said titanium dioxide is 5 ~ 300nm, and the specific area of said titanium dioxide is 100-300m
2/ g.
4. preparation method as claimed in claim 1 is characterized in that, said lithium source comprises at least a in lithium carbonate, lithium nitrate and the lithium hydroxide;
Said dispersant comprises at least a in water, ethanol or the acetone;
Said carbon source comprises at least a in glucose, sucrose and the starch.
5. preparation method as claimed in claim 1 is characterized in that, the condition that the ratio between said titanium dioxide and the lithium source should meet is: the mol ratio between the Ti:Li is 1: (0.8-0.88).
6. preparation method as claimed in claim 1 is characterized in that, the mol ratio between the said Ti:Li is 1: (0.824-0.848).
7. preparation method as claimed in claim 1 is characterized in that, the raw material that said titanium dioxide and lithium source are formed and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3);
Said carbon source accounts for the 1%-20% of said intermediate product and carbon source total weight;
The raw material that said intermediate product and carbon source are formed and the weight ratio of dispersant are (1 ~ 2): (1 ~ 3).
8. preparation method as claimed in claim 7 is characterized in that, the raw material that said titanium dioxide and lithium source are formed and the weight ratio of dispersant are (1 ~ 1.5): (1 ~ 2);
Said carbon source accounts for the 3%-6% of said intermediate product and carbon source total weight;
The raw material that said intermediate product and carbon source are formed and the weight ratio of dispersant are (1 ~ 1.5): (1 ~ 2).
9. preparation method as claimed in claim 1; It is characterized in that; Said second step is specially: the mixture of oven dry is positioned in the crucible, then crucible is put in the Muffle furnace, then under first atmosphere with 400 ~ 800 ℃ temperature preroast 2 ~ 36 hours; Naturally cool to room temperature then, obtain intermediate product;
Said the 4th step is specially: the mixture of the intermediate product after will drying, carbon source and dispersant is positioned in the crucible; Then crucible is put in the atmosphere furnace; Under second atmosphere, carried out after baking 2 ~ 36 hours then with 700 ~ 950 ℃ temperature; Naturally cool to room temperature then, finally obtain nano-sized carbon coating spinelle lithium titanate.
10. like claim 1 or 9 described preparation methods, it is characterized in that said first atmosphere is air atmosphere, inert gas atmosphere or reducing atmosphere, said second atmosphere is inert gas atmosphere or reducing atmosphere.
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| CN102820461A (en) * | 2012-08-20 | 2012-12-12 | 上海交通大学 | Method for preparing carbon-coated nano-lithium titanate by ethylene diamine tetraacetic acid-citric acid (EDTA-CA) joint complexation |
| CN102891290A (en) * | 2012-07-05 | 2013-01-23 | 深圳市海太阳实业有限公司 | Silicon carbon composite material, lithium ion battery and negative pole piece thereof |
| CN102945952A (en) * | 2012-12-05 | 2013-02-27 | 吉林大学 | Method for preparing anode material carbon coated lithium titanate for lithium ion power batteries |
| CN103022462A (en) * | 2012-12-20 | 2013-04-03 | 中国东方电气集团有限公司 | Preparation method for high-conductivity lithium titanate cathode material of lithium battery |
| CN103441257A (en) * | 2013-08-12 | 2013-12-11 | 四川大学 | Preparation method for lithium titanate material |
| CN103682278A (en) * | 2013-12-26 | 2014-03-26 | 山东精工电子科技有限公司 | Preparation method of nanocarbon coated lithium titanate cathode material |
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