CN106129388B - A kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation method - Google Patents
A kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation method Download PDFInfo
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- CN106129388B CN106129388B CN201610841800.5A CN201610841800A CN106129388B CN 106129388 B CN106129388 B CN 106129388B CN 201610841800 A CN201610841800 A CN 201610841800A CN 106129388 B CN106129388 B CN 106129388B
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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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
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- H—ELECTRICITY
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- 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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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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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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- H01M4/02—Electrodes composed of, or comprising, active material
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Abstract
The present invention is a kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation method.Method includes the following steps: ferrous sulfate, phosphoric acid, dissolution of ascorbic acid are 1. obtained A liquid in the mixed solvent；Three-dimensional carbon skeleton is dispersed in the in the mixed solvent containing lithium hydroxide and obtains B liquid, then B liquid is added to and obtains the precursor solution of LiFePO4 in A liquid；2. 1. step is used ball milling after gained ferric lithium phosphate precursor is mixed with glucose；3. sintering finally obtains LiFePO4/three-dimensional carbon skeleton/carbon composite under protective gas atmosphere.Electronics may be implemented by putting the conduction to three-dimensional space, the intergranular electronic conduction ability of positive electrode can be improved and then enhancing positive electrode chemical property in the material that the present invention obtains.
Description
Technical field
The present invention relates to anode material for lithium-ion batteries preparation fields, in particular to a kind of LiFePO4/three-dimensional carbon skeleton/carbon
The preparation method of composite material.
Background technique
Since sony company releases commodity lithium ion battery for the first time since 1991, lithium ion battery is with its open-circuit voltage
It is high, have extended cycle life, energy density is high, self discharge is low, memory-less effect, it is environmentally friendly the advantages that be widely used in people's work
Make, the various aspects of study, life.In recent years, as the market demand of power battery and large-scale power energy storage device constantly increases
Add, occurs the power and accumulation power supply using lithium ion battery as carrier successively.
LiFePO4As a member in positive electrode material of lithium secondary cell, because its is cheap, environmental-friendly, voltage platform is flat,
The advantages that safety is good is considered as one of most promising anode material for lithium-ion batteries.But due to LiFePO4Without layer
Shape LiCoO2、LiMnO2With spinelle shape LiMn2O4Two-dimentional or three-dimensional Li+Migrating channels, ionic conductivity and electronic conductance
Rate is relatively low, and wherein ionic conductivity is 10-11cm2/ S electronic conductivity is 10-9S/cm, capacity cannot when high current charge-discharge
It all plays and influences its application.
Various researchs are done to solve above-mentioned two disadvantage people, such as coated with conductive agent, passes through metal ion mixing
Different synthetic methods reduce particle size etc..Wherein carbon coating is exactly a kind of important modification means.Carbon coating can be mentioned effectively
High LiFePO4The electric conductivity of particle.But LiFePO4Surface coated carbon is inert matter, and carbon additional amount excessively not only can shadow
The tap density and processing performance of material are rung, while reducing LiFePO to a certain extent4With the contact area of electrolyte, resistance
Li is hindered+Movement.And using the open cladding of porous carbon materials progress that material electronics electrical conductivity both can be improved does not influence
Li+Movement, it is also less to the research that cladding carbon material carries out porous at present, it is to improve material property very by carbon coated porous
A promising direction.Currently, having done a lot of work in carbon coating process aspect.For example, Chinese patent (publication No.
CNIO5390682A, date of publication 2016.03.09) system of LiFePO4 microballoon/three-dimensional grapheme combination electrode material a kind of is disclosed
Preparation Method, step are: weighing 1g ferric phosphate and 1g glucose is scattered in 80ml deionized water, be placed in 100ml hydrothermal reaction kettle
In 120 DEG C of reaction 5h, wash dry obtained " spherical source of iron " polyhydroxy ferric phosphate microballoon.2g polyhydroxy ferric phosphate microballoon (is pressed
Ferrous metal quality), 0.3g lithium acetate (by lithium metal quality) and 0.6g graphene oxide be scattered in deionized water, it is dry；It will
Said mixture is placed in high temperature process furnances, carries out high temperature thermal response in a nitrogen atmosphere, and reaction temperature is 750 DEG C, when reaction
Between be 8h, heating rate be 2 DEG C/min；Obtain " LiFePO4Micro-/three-dimensional grapheme " composite material.The above method uses oxygen
Graphite alkene as three-dimensional conductive skeleton raw material graphene oxide price first it is more expensive be unfavorable for industrial applications, it is in addition above-mentioned
The basic principle that method constructs three-dimensional grapheme is that layered graphite oxide alkene carries out self assembly by layer structure in hydro-thermal reaction
Be assembled into three-dimensional cavernous structure, but the above method be one-step method i.e. the self assembly of graphene oxide hydro-thermal when will receive its in solution
The influence of his ion, the three-dimensional grapheme structure easily caused are imperfect.Chinese patent (CNIO557622OA is announced, it is public
Open a day 2016.05.11) preparation of cellular carbon-coated LiFePO 4 for lithium ion batteries positive electrode a kind of is disclosed, step is: the anhydrous second of 136.2g
Alcohol is dissolved in 136.2g deionization, pours into reaction kettle；Weigh 157gLiFePO4, 19.4g glucose and 88.2g ammonium hydrogen carbonate
It is put into reaction kettle after mixing, lh is sufficiently stirred in mixture.Slurry after mixing evenly is put into vacuum freeze drier
In, freeze lh at -10 DEG C, then the dry 5h under vacuum 13Pa environment.Solid is put into 100 DEG C of baking ovens after drying, dries lh, nitrogen
The lower 750 DEG C of sintering 2h of gas shielded atmosphere.It is cooled to room temperature, 325 meshes is crossed after grinding, obtain cellular carbon coating LiFePO4/C。
The principle that the above method prepares porous carbon is that ammonium salt gas-phase decomposition carries out pore-creating and obtained cellular carbon, but cellular carbon with
LiFePO4The only other LiFePO of physical mixed4It is not present in the hole configurations of cellular carbon, cellular carbon, which only plays, leads
Electro ultrafiltration can not play the role of limiting partial size.
Summary of the invention
The present invention is for LiFePO present in current techniques4Material electronics poorly conductive, conventional packet carbon are in material table
Bread covers carbon material, and serious polarization in this cladding mode material charge and discharge process, big high rate performance is poor, proposes using three-dimensional
Porous carbon skeleton is in LiFePO4Three-dimensional conductive network is constructed between particle.The present invention can three-dimensional transmission electronics using three-dimensional porous carbon skeleton
Characteristic, increase electronics in LiFePO4Transmission channel between particle, ensure while improving material electronics electrical conductivity it is higher from
Sub- conductivity.The not exclusively carbon-coated LiFePO4 of fractional open/three-dimensional carbon skeleton/carbon composite is constructed, material is improved
Chemical property.
Technical solution of the present invention are as follows:
A kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation method, comprising the following steps:
1. ferrous sulfate, phosphoric acid, dissolution of ascorbic acid are obtained A liquid in the mixed solvent；Three-dimensional carbon skeleton is dispersed in and is contained
There is the in the mixed solvent of lithium hydroxide, obtain B liquid by magnetic agitation 2-12h, then B liquid 15-20min is added dropwise in A liquid
The precursor solution of LiFePO4 is obtained, is then placed it in high-temperature high-pressure reaction kettle, is heated to 160-300 DEG C, when reaction
Between be 1-20h, after reaction ax cooled to room temperature, respectively use distilled water, ethyl alcohol centrifuge washing, after vacuum drying be made phosphorus
Sour iron lithium presoma；
Wherein, the ion molar ratio is lithium ion: iron ion: phosphate anion=3-3.3:1:1；Precursor solution
Middle lithium concentration is 0.1-1mol/L；Ascorbic acid concentrations are 0.03-0.2mol/L in precursor solution；Quality compares theoretical amount
LiFePO4: three-dimensional carbon skeleton=1:0.1-0.005；Volume ratio A liquid: B liquid=5:3；Mixed solvent in A liquid and B liquid is water
With the mixture of ethylene glycol, volume ratio is water: ethylene glycol=1:2；
2. 1. step is used ball milling after gained ferric lithium phosphate precursor is mixed with glucose, auxiliary agent is that ethyl alcohol is mixed
Close object；Wherein, 0.5-10ml ethyl alcohol is added in every gram of presoma；
Wherein, mass ratio is ferric lithium phosphate precursor: glucose=1-10:1, rotational speed of ball-mill 200-500r/min, ball milling
Time 2-10h；
3. by being put into tube furnace after the step 2. drying of gained mixture, under protective atmosphere atmosphere, first at 240-390 DEG C
Under the conditions of pre-burning 1-5h, cool to room temperature with the furnace, then ground broken, add in tube furnace, equally in protective atmosphere
Under, 450-780 DEG C of sintering 3-12h cools to room temperature with the furnace, finally obtains LiFePO4/three-dimensional carbon skeleton/carbon composite；
The step 1. in precursor solution volume be reactor volume 30-90%.
The protective atmosphere is nitrogen, argon gas, one or more gaseous mixture atmosphere in hydrogen.
Phosphorus content is the 5-30% of LiFePO4 quality in final product, it is carbon containing respectively from being added in water-heat process
Carbon after the glucose carbonization that three-dimensional carbon skeleton and presoma mechanical milling process are added.
The preparation method of the three-dimensional carbon skeleton, comprising the following steps:
1) carbon source, catalyst are added in ethyl alcohol and are stirred, be then dried in vacuo in 30-90 DEG C, obtain mixture A；
Wherein, quality is than carbon source: catalyst=5-50:1；Every gram of carbon source adds 1-3ml ethyl alcohol；The carbon source is grape
It is sugar, sucrose, starch, oxalic acid, cellulose, ferrous gluconate, one or more in ferrous oxalate；Catalyst is ferrous sulfate, chlorine
Change one of iron, frerrous chloride, nickel sulfate, nickel chloride and cobaltous sulfate or a variety of；
2) ball milling 1-9h after mixing mixture A obtained by step 1) with perforating agent, mass ratio are mixture A: drilling
Agent=1:100-5000；Obtain mixture B；Rotational speed of ball-mill 100-500r/min；
3) mixture B obtained by step 2) is compressed to being pressed into for 1-2g size with infrared tablet press machine under 1-50MPa pressure
Tablet；
4) tablet obtained by step 3) is sintered in protective atmosphere, comprising the following steps:
A, 350-400 DEG C is warming up under protective atmosphere from room temperature with 2-5 DEG C/min heating rate, outlet temperature is known as
T1；And 60-120min is kept the temperature at a temperature of T1；
B, 600-700 DEG C is warming up under protective atmosphere from T1 with 1-4 DEG C/min heating rate, outlet temperature is known as T2；
60-180min is kept the temperature at a temperature of T2；
C, 700-900 DEG C is warming up under protective atmosphere from T2 with 1-3 DEG C/min heating rate, outlet temperature is known as T3；
120-240min is kept the temperature at a temperature of T3；
D, 600-700 DEG C is cooled under protective atmosphere from T3 with 0.2-1 DEG C/min rate of temperature fall, outlet temperature T4；
E, 500-600 DEG C is cooled under protective atmosphere from T4 with 0.2-1 DEG C/min rate of temperature fall, outlet temperature T5；
F, 350-450 DEG C is cooled under protective atmosphere from T5 with 1-1.5 DEG C/min rate of temperature fall, outlet temperature T6；
G, from T6, Temperature fall obtains mixture C to room temperature under protective atmosphere；
Wherein, the protective atmosphere in step A-F is nitrogen or argon atmosphere.
5) 4) mixture C obtained is put into distilled water, is completely dissolved to perforating agent, solid is pulled out, after vacuum drying
Obtain three-dimensional carbon skeleton.
In the step 2) perforating agent be sodium chloride, potassium chloride, calcium chloride, lithium chloride, sodium carbonate, it is a kind of in calcium carbonate or
It is a variety of.
Substantive distinguishing features of the invention are as follows:
The present invention is (its simple process, easy better than current three-dimensional ordered macroporous, three-dimensional meso-hole by preparing to three-dimensional carbon skeleton
The preparation of material), it is then used as the matrix of hydro-thermal reaction, the hole on three-dimensional carbon skeleton limits hydro-thermal to a certain extent
The growth of partial size in the process.On the other hand three-dimensional carbon skeleton has three-dimensional conductive compared with the one-dimensional carbon-coating that material surface routinely coats
Ability.
In the prior art, the presoma of hydro-thermal method preparation coats one layer of agraphitic carbon (without fixed using carbon source on the surface of the material
Type carbon conductive is poor), electronics conduction can only be contacted by the point-to-point between particle conducts.Or by presoma and graphene etc.
Lamella conductive material is compound, and the conduction of electronics point to face is achieved.And electronics may be implemented by point to three-dimensional space in the present invention
Conduction can be improved the intergranular electronic conduction ability of positive electrode and reduce the enhancing positive electrode chemical property in turn that polarizes.
The invention has the benefit that
The invention discloses a kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation methods.Grape is mixed first
Sugar, ferrous sulfate then by mixture and sodium chloride ball milling, then use infrared tabletting machine, wash away chlorine after sintering carbonization
Change sodium and three-dimensional carbon skeleton is made.Using obtained three-dimensional carbon skeleton as the matrix of LiFePO4 hydro-thermal reaction, LiFePO4/tri- are prepared
Tie up carbon skeleton/carbon composite.
The carbon source that uses when preparing three-dimensional carbon skeleton, catalyst, perforating agent are glucose common in industry, sulfuric acid Asia
Iron, sodium chloride, the selection of the above raw material can reduce production cost.
When preparing three-dimensional carbon skeleton, using ferrous sulfate, there are two purposes: the micro addition of ferrous sulfate is with sintering first
Process is reduced into Fe simple substance by carbon simple substance, is the structure of a kind of " nano island " under high temperature, when sintering in tube furnace program liter
Temperature dissolves in this " nano island " structure with program slow cooling process agraphitic carbon mechanism to be precipitated again the stone of carbon can be improved
Blackization degree, and then enhance the electric conductivity of three-dimensional carbon skeleton.Secondly leading for carbon skeleton can be enhanced after being converted into Fe simple substance in ferrous sulfate
Electrically.
LiFePO4 is nucleated on the hole wall of three-dimensional carbon skeleton first under the action of Gibbs free energy in water-heat process
Growth, ultimately forms LiFePO4/three-dimensional carbon skeleton structure, due to growing in aperture, three-dimensional carbon skeleton can play control partial size
Effect.Presence additionally, due to three-dimensional carbon skeleton is transferred out from LiFePO4 electrically realized by o'clock to three during discharge
The transmission of dimension space, this effective mechanisms of electronic can reduce the polarization phenomena in material charge and discharge process.
As described in Example 1, when it is LiFePO4 3% that three-dimensional carbon skeleton quality, which is added, material specific volume under 0.2C multiplying power
Amount is that 156.7mAh/g reaches the 92.18% of theoretical specific capacity 170mAh/g.Better than same carbon content but three-dimensional carbon skeleton material is not added
151.6mAh/g under the 0.2C multiplying power of material.
Detailed description of the invention
Fig. 1 is LiFePO4 obtained in embodiment 1/three-dimensional carbon skeleton/carbon composite SEM figure；
Fig. 2 is phosphoric acid obtained in LiFePO4/three-dimensional carbon skeleton/carbon composite obtained in embodiment 1 and embodiment 3
Iron lithium/carbon composite material cycle charge-discharge curve graph；
Fig. 3 is obtained LiFePO4/three-dimensional carbon skeleton/carbon composite XRD spectra in embodiment 1.
Specific embodiment:
Present invention will be further explained below with reference to the attached drawings and examples.
Reaction equation in water-heat process of the invention are as follows:
3LiOH+FeSO4+H3PO4→LiFePO4+Li2SO4+3H2O
Embodiment 1:
1. ferrous sulfate (0.048mol), phosphoric acid (0.048mol), ascorbic acid (0.014mol), are dissolved in after weighing
200ml water and ethylene glycol by volume=in the mixed solvent of 1:2 composition, referred to as A liquid；According to theoretical amount LiFePO4: three-dimensional
Three-dimensional carbon skeleton is dispersed in the water and ethylene glycol that 120ml contains lithium hydroxide (0.144mol) by carbon skeleton=1:0.03 mass ratio
By volume=1:2 in the mixed solvent, magnetic agitation 12h obtain B liquid, and then B liquid 20min is added dropwise in A liquid and obtains phosphoric acid
The precursor solution of iron lithium, places it in high-temperature high-pressure reaction kettle, and lithium concentration is 0.45mol/L in precursor solution；
The volume of precursor solution is the 80% of reactor volume, 240 DEG C, reaction time 4h is heated to, to reaction kettle natural cooling
Ferric lithium phosphate precursor is made after being dried in vacuo three times after to room temperature with distilled water, each centrifuge washing of ethyl alcohol；
2. by presoma LiFePO4: glucose=15:2 mass ratio weighs glucose 0.4320g, is with 5ml ethyl alcohol
Auxiliary agent 300r/min ball milling 6h.
3. being sintered under protective atmosphere atmosphere, by being put into tube furnace after the step 2. drying of gained mixture first at 350 DEG C
Under the conditions of pre-burning 3h, cool to room temperature with the furnace, then ground it is broken (until without the obvious blocky-shaped particle reunited together,
Following embodiment is same), it adds in tube furnace, is equally sintered under protective atmosphere, sintering process is respectively 650 DEG C, 6h, with furnace
It is cooled to room temperature, finally obtains the composite ferric lithium phosphate material for being constituted three-dimensional conductive network with three-dimensional carbon skeleton and carbon；
Wherein, protective atmosphere is nitrogen atmosphere.
Phosphorus content is the 6% of LiFePO4 quality in final product, and 6% carbon is respectively from 3% be added in water-heat process
Carbon 3% after the glucose carbonization that three-dimensional carbon skeleton and presoma mechanical milling process are added.
The preparation method of the three-dimensional carbon skeleton, comprising the following steps:
1) it by glucose, ferrous sulfate 22:1 in mass ratio, is sufficiently stirred and is scattered in ethyl alcohol (every gram of carbon source corresponds to 1.5ml
Ethyl alcohol) in, 60 DEG C of vacuum drying obtain mixture A；
2) mixture A obtained by step 1) and sodium chloride 1:240 in mass ratio, 300r/min ball milling 6h are obtained into mixture
B；
3) by mixture B obtained by step 2), with infrared tablet press machine, in 20MPa pressure, 1g is pressed into tablet next time；
4) tablet obtained by step 3) is sintered in protective atmosphere, processing step are as follows:
A, heating process is warming up to 400 DEG C from room temperature with 4 DEG C/min heating rate under protective atmosphere, and outlet temperature claims
For T1；And 60min is kept the temperature at a temperature of T1；
B, heating process is warming up to 650 DEG C from T1 with 2 DEG C/min heating rate under protective atmosphere, and outlet temperature is known as
T2；And 120min is kept the temperature at a temperature of T2；
C, heating process is warming up to 750 DEG C from T2 with 1 DEG C/min heating rate under protective atmosphere, and outlet temperature is known as
T3；And 180min is kept the temperature at a temperature of T3；
D, temperature reduction technology cools to 650 DEG C from T3 with 0.5 DEG C/min rate of temperature fall under protective atmosphere, and outlet temperature is
T4；
E, temperature reduction technology cools to 550 DEG C from T4 with 1 DEG C/min rate of temperature fall, outlet temperature T5 under protective atmosphere；
F, temperature reduction technology cools to 400 DEG C from T5 with 1.5 DEG C/min rate of temperature fall under protective atmosphere, and outlet temperature is
T6；
G, temperature reduction technology, from T6, Temperature fall obtains mixture C to room temperature under protective atmosphere；
Wherein the protective atmosphere in step A-F is nitrogen atmosphere.
5) 4) mixture C obtained is put into distilled water, be completely dissolved to perforating agent (distilled water that midway more renews,
A small amount of distilled water for impregnating three-dimensional carbon skeleton is taken to instill AgNO3Solution, no white precipitate generate, it was demonstrated that perforating agent is completely dissolved), fishing
Solid out obtains three-dimensional carbon skeleton after vacuum drying.
From in Fig. 1 it can be seen that three-dimensional carbon skeleton prepared by the present invention shows irregular three-dimensional aperture layer structure, hole
Diameter is between 100nm-1 μm, and lithium iron phosphate particles are grown in three-dimensional carbon frame aperture hole in hydro-thermal reaction.LiFePO4 is more than enough by energy
The three-dimensional carbon skeleton of access conduction not exclusively coats, and constructs the not exclusively carbon-coated LiFePO4 of fractional open/three-dimensional carbon skeleton/carbon
On the one hand the addition of composite material, three-dimensional carbon skeleton limits the undue growth of LiFePO 4 material particle in water-heat process, another
Aspect enhances the electric conductivity between material granule.
Fig. 2 is to carry out charge-discharge test performance curve to battery using CT2001A type LAND tester, and voltage range is
2.5-4.2V, 25 DEG C of test temperature.3%+3% carbon of three-dimensional carbon skeleton (glucose carbonization is added it can be seen that being used under 0.2C multiplying power
) LiFePO4 specific capacity can reach 156.7mAh/g, and use identical preparation process that 6% carbon (glucose is only added
Carbonization-embodiment 3) lithium ferric manganese phosphate 0.2C multiplying power under specific capacity be 151.6mAh/g.
Fig. 3 can be seen that a process for preparing the XRD spectra of LiFePO4 match with standard spectrogram, and peak type point
Sharp free from admixture peak occurs, and the complete LiFePO 4 material of crystal form can be prepared by explanation this method.
Embodiment 2:
1. ferrous sulfate (0.048mol), phosphoric acid (0.048mol), ascorbic acid (0.018mol), are dissolved in after weighing
200ml water and ethylene glycol by volume=in the mixed solvent of 1:2 composition, referred to as A liquid；According to theoretical amount LiFePO4: three-dimensional
Three-dimensional carbon skeleton is dispersed in water that 120ml contains lithium hydroxide (0.1584mol) to carbon skeleton=1:0.1 mass ratio and ethylene glycol is pressed
Volume ratio=1:2 in the mixed solvent, magnetic agitation 10h obtain B liquid, and then B liquid 15min is added dropwise in A liquid and obtains ferric phosphate
The precursor solution of lithium, places it in high-temperature high-pressure reaction kettle, and lithium concentration is 0.495mol/L in precursor solution；Before
The volume for driving liquid solution is the 60% of reactor volume, is heated to 200 DEG C, reaction time 6h is naturally cooled to reaction kettle
Ferric lithium phosphate precursor is made after being dried in vacuo three times after room temperature with distilled water, each centrifuge washing of ethyl alcohol；
2. by presoma LiFePO4: it is to help that glucose=15:8 mass ratio, which weighs glucose 0.8640g with 8ml ethyl alcohol,
Agent 400r/min ball milling 1h.
3. being sintered under protective atmosphere atmosphere, by being put into tube furnace after the step 2. drying of gained mixture first at 390 DEG C
Under the conditions of pre-burning 2h, cool to room temperature with the furnace, then ground broken, add in tube furnace, equally under protective atmosphere
Sintering, sintering process is respectively 700 DEG C, and 4h cools to room temperature with the furnace, finally obtains and is constituted three-dimensional conductive with three-dimensional carbon skeleton and carbon
The composite ferric lithium phosphate material of network；
Wherein, protective atmosphere is hydrogen atmosphere.
Phosphorus content is the 22% of LiFePO4 quality in final product, and 22% carbon is respectively from being added in water-heat process
Carbon 12% after the glucose carbonization that 10% carbon skeleton and presoma mechanical milling process are added.
The preparation method of the three-dimensional carbon skeleton, comprising the following steps:
1) it by ferrous gluconate, cobaltous sulfate 10:1 in mass ratio, is sufficiently stirred and is scattered in ethyl alcohol (every gram of carbon source correspondence
2ml ethyl alcohol) in, 50 DEG C of vacuum drying obtain mixture A；
2) mixture A obtained by step 1) and sodium carbonate 1:1000 in mass ratio, 200r/min ball milling 4h are obtained into mixture
B；
3) by mixture B obtained by step 2), with infrared tablet press machine, in 10MPa pressure, 1.5g is pressed into tablet next time；
4) tablet obtained by step 3) is sintered in protective atmosphere, processing step are as follows:
A, heating process is warming up to 350 DEG C from room temperature with 5 DEG C/min heating rate under protective atmosphere, and outlet temperature claims
For T1；And 120min is kept the temperature at a temperature of T1；
B, heating process is warming up to 700 DEG C from T1 with 1 DEG C/min heating rate under protective atmosphere, and outlet temperature is known as
T2；And 180min is kept the temperature at a temperature of T2；
C, heating process is warming up to 800 DEG C from T2 with 2 DEG C/min heating rate under protective atmosphere, and outlet temperature is known as
T3；And 240min is kept the temperature at a temperature of T3；
D, temperature reduction technology cools to 700 DEG C from T3 with 0.2 DEG C/min rate of temperature fall under protective atmosphere, and outlet temperature is
T4；
E, temperature reduction technology cools to 600 DEG C from T4 with 0.5 DEG C/min rate of temperature fall under protective atmosphere, and outlet temperature is
T5；
F, temperature reduction technology cools to 350 DEG C from T5 with 1 DEG C/min rate of temperature fall, outlet temperature T6 under protective atmosphere；
G, temperature reduction technology, from T6, Temperature fall obtains mixture C to room temperature under protective atmosphere；
Wherein the protective atmosphere in step A-F is argon atmosphere.
5) 4) mixture C obtained is put into distilled water, be completely dissolved to perforating agent (distilled water that midway more renews,
A small amount of distilled water for impregnating three-dimensional carbon skeleton is taken to instill AgNO3Solution, no precipitating generate, it was demonstrated that perforating agent is completely dissolved), it pulls out solid
Body obtains three-dimensional carbon skeleton after vacuum drying.
Embodiment 3:
1. ferrous sulfate (0.048mol), phosphoric acid (0.048mol), ascorbic acid (0.014mol), are dissolved in after weighing
200ml water and ethylene glycol by volume=in the mixed solvent of 1:2 composition, referred to as A liquid；Lithium hydroxide (0.144mol) is dispersed
The 120ml water contained and ethylene glycol by volume=1:2 in the mixed solvent, obtain B liquid, B liquid 20min be then added dropwise to A
The precursor solution that LiFePO4 is obtained in liquid, places it in high-temperature high-pressure reaction kettle, lithium concentration in precursor solution
For 0.45mol/L；The volume of precursor solution is the 80% of reactor volume, is heated to 240 DEG C, reaction time 4h, to anti-
Answer obtained ferric lithium phosphate precursor after be dried in vacuo three times after kettle cooled to room temperature with distilled water, each centrifuge washing of ethyl alcohol；
2. by presoma LiFePO4: it is to help that glucose=15:4 mass ratio, which weighs glucose 0.8640g with 5ml ethyl alcohol,
Agent 300r/min ball milling 6h.
3. being sintered under protective atmosphere atmosphere, by being put into tube furnace after the step 2. drying of gained mixture first at 350 DEG C
Under the conditions of pre-burning 3h, cool to room temperature with the furnace, then ground broken, add in tube furnace, equally under protective atmosphere
Sintering, sintering process is respectively 650 DEG C, and 6h cools to room temperature with the furnace, finally obtains lithium iron phosphate/carbon composite material；
Wherein, protective atmosphere is nitrogen atmosphere.
Phosphorus content is the 6% of LiFePO4 quality in final product.
Unaccomplished matter of the present invention is well-known technique.
Claims (5)
1. a kind of LiFePO4/three-dimensional carbon skeleton/carbon composite preparation method, it is characterized in that method includes the following steps:
1. ferrous sulfate, phosphoric acid, dissolution of ascorbic acid are obtained A liquid in the mixed solvent；Three-dimensional carbon skeleton is dispersed in containing hydrogen
The in the mixed solvent of lithia obtains B liquid by magnetic agitation 2-12h, and then B liquid 15-20min is added dropwise in A liquid and is obtained
The precursor solution of LiFePO4, then places it in high-temperature high-pressure reaction kettle, is heated to 160-300 DEG C, and the reaction time is
1-20h uses distilled water, ethyl alcohol centrifuge washing after reaction kettle cooled to room temperature respectively, and ferric phosphate is made after vacuum drying
Lithium presoma；
Wherein, ion molar ratio is lithium ion: iron ion: phosphate anion=3-3.3:1:1；Lithium ion is dense in precursor solution
Degree is 0.1-1mol/L；Ascorbic acid concentrations are 0.03-0.2mol/L in precursor solution；Quality is than theoretical amount LiFePO4:
Three-dimensional carbon skeleton=1:0.1-0.005；Volume ratio A liquid: B liquid=5:3；Mixed solvent in A liquid and B liquid is water and ethylene glycol
Mixture, volume ratio are water: ethylene glycol=1:2；
2. 1. step is used ball milling after gained ferric lithium phosphate precursor is mixed with glucose, auxiliary agent is that ethyl alcohol is mixed
Object；Wherein, 0.5-10ml ethyl alcohol is added in every gram of presoma；
Wherein, mass ratio is ferric lithium phosphate precursor: glucose=1-10:1, rotational speed of ball-mill 200-500r/min, Ball-milling Time
2-10h；
3. first pre- under the conditions of 240-390 DEG C under protective atmosphere by being put into tube furnace after the step 2. drying of gained mixture
1-5h is burnt, cools to room temperature with the furnace, is then ground and is crushed, added in tube furnace, equally under protective atmosphere, 450-
780 DEG C of sintering 3-12h, cool to room temperature with the furnace, finally obtain LiFePO4/three-dimensional carbon skeleton/carbon composite；
The preparation method of the three-dimensional carbon skeleton, comprising the following steps:
1) carbon source, catalyst are added in ethyl alcohol and are stirred, be then dried in vacuo in 30-90 DEG C, obtain mixture A；
Wherein, quality is than carbon source: catalyst=5-50:1；Every gram of carbon source adds 1-3ml ethyl alcohol；The carbon source is glucose, sugarcane
It is sugar, starch, oxalic acid, cellulose, ferrous gluconate, one or more in ferrous oxalate；Catalyst is ferrous sulfate；
2) ball milling 1-9h after mixing mixture A obtained by step 1) with perforating agent, mass ratio are mixture A: perforating agent=
1:100-5000；Obtain mixture B；Rotational speed of ball-mill 100-500r/min；
3) what mixture B obtained by step 2) was compressed under 1-50MPa pressure to 1-2g size with infrared tablet press machine is pressed into tablet；
4) tablet obtained by step 3) is sintered in protective atmosphere, comprising the following steps:
A, 350-400 DEG C is warming up under protective atmosphere from room temperature with 2-5 DEG C/min heating rate, outlet temperature is known as T1；And
60-120min is kept the temperature at a temperature of T1；
B, 600-700 DEG C is warming up under protective atmosphere from T1 with 1-4 DEG C/min heating rate, outlet temperature is known as T2；In T2
At a temperature of keep the temperature 60-180min；
C, 700-900 DEG C is warming up under protective atmosphere from T2 with 1-3 DEG C/min heating rate, outlet temperature is known as T3；In T3
At a temperature of keep the temperature 120-240min；
D, 600-700 DEG C is cooled under protective atmosphere from T3 with 0.2-1 DEG C/min rate of temperature fall, outlet temperature T4；
E, 500-600 DEG C is cooled under protective atmosphere from T4 with 0.2-1 DEG C/min rate of temperature fall, outlet temperature T5；
F, 350-450 DEG C is cooled under protective atmosphere from T5 with 1-1.5 DEG C/min rate of temperature fall, outlet temperature T6；
G, from T6, Temperature fall obtains mixture C to room temperature under protective atmosphere；
5), 4) mixture C obtained is put into distilled water, is completely dissolved to perforating agent, is pulled solid out, obtained after vacuum drying
Three-dimensional carbon skeleton.
2. LiFePO4 as described in claim 1/three-dimensional carbon skeleton/carbon composite preparation method, it is characterized in that described
Step 3. in protective atmosphere be nitrogen, argon gas, one or more gaseous mixture atmosphere in hydrogen.
3. LiFePO4 as described in claim 1/three-dimensional carbon skeleton/carbon composite preparation method, it is characterized in that described
Step 1. in precursor solution volume be reactor volume 30-90%.
4. LiFePO4 as described in claim 1/three-dimensional carbon skeleton/carbon composite preparation method, it is characterized in that described three
In the preparation method for tieing up carbon skeleton, perforating agent is a kind of in sodium chloride, potassium chloride, calcium chloride, lithium chloride and sodium carbonate in step 2)
Or it is a variety of.
5. LiFePO4 as described in claim 1/three-dimensional carbon skeleton/carbon composite preparation method, it is characterized in that described three
In the preparation method for tieing up carbon skeleton, the protective atmosphere in step A-F is nitrogen or argon atmosphere.
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