CN107565132B - The preparation method of the ferric phosphate and its ferric phosphate of preparation, the LiFePO4 and lithium battery of the preparation method of LiFePO4 and its preparation - Google Patents
The preparation method of the ferric phosphate and its ferric phosphate of preparation, the LiFePO4 and lithium battery of the preparation method of LiFePO4 and its preparation Download PDFInfo
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Abstract
The invention discloses the preparation methods of ferric phosphate presoma and its ferric phosphate of preparation and preparation method and the LiFePO4 prepared therefrom of LiFePO4 prepared particularly suitable for LiFePO4；The preparation method of ferric phosphate includes the following steps：Reduced iron powder is added in into the aqueous solution containing sulfuric acid and organic acid, is reacted 5 10 hours in 60 90 DEG C, high Magnetic filter, obtains ferrous sulfate aqueous solution after the completion of reaction；Into ferrous sulfate aqueous solution, the mixed liquor being made of ammonium persulfate, ammonium phosphate, nano-particle controlling agent is added dropwise, it is precipitated below 3 in 60 80 DEG C, pH value, it is stirred reaction 58 hours, Magnetic filter is removed after reaction, filter cake is pressed into, rinsing, spraying drying, powder processed obtain phosphoric acid iron product.The present invention makes electric conductivity, tap density and the stability of the LiFePO4 finally obtained obtain sufficient raising by being improved to LiFePO4 preparation process and raw material, the preparation process of the ferric phosphate and ingredient of raw material and initial raw material ferrous sulfate.
Description
Technical field
The invention belongs to new energy fields, and in particular to before a kind of ferric phosphate for being particularly suitable for LiFePO4 and preparing
Drive ferric phosphate prepared by the preparation method of body and the method, a kind of preparation method of novel phosphoric acid iron lithium and phosphoric acid prepared therefrom
Iron lithium and the lithium battery including LiFePO4.
Background technology
Lithium iron phosphate electrode material is mainly used for various lithium ion batteries.The NTT Japanese from 1996 is disclosed for the first time
Ay(A is the combination LiFeCoPO of both alkali metal, M Co, Fe to MPO44) olivine structural anode material of lithium battery it
Afterwards, Texas, USA in 1997 stands the research group such as university John.B.Goodenough, has also then reported LiFePO4's
Reversibly move into the characteristic of abjection lithium.Olivine structural (LiMPO is coincidentally delivered with Japan in the U.S.4) so that the material
Material receives great attention, and causes extensive research and rapidly development.With traditional lithium ion secondary battery positive electrode material
Material, the LiMn of spinel structure2O4With the LiCoO of layer structure2It compares, LiMPO4Raw material source more extensively, price it is lower
Honest and clean and non-environmental-pollution.
LiFePO4For firm phosphoric acid tetrahedral framework, because of the P-O keys present in crystal structure, even if repeatedly into
Row discharge and recharge reaction, crystalline texture are also highly stable.For example, even if when material reaches 400 DEG C, oxygen will not be released, greatly
The safety for improving battery, be steady in a long-term and the active material of quick charge；Its source is extensive, toxicity is low simultaneously, safety
Property it is high, thus as most important positive electrode active materials used for electric vehicle.
But there is also following deficiencies for LiFePO4：Poorly conductive, tap density are low, performance is unstable.
In order to solve these problems, people are explored in terms of three：1) pattern and structure are controlled：Control crystal shape
Looks and granular size；2) it coats：In LiFePO4 surface coated with conductive substance, for example, coated with conductive carbon, coats metal powder etc.；
3) it adulterates：In LiFePO4 crystal, micro impurity metal ion is introduced, improves electronics and ionic conductivity.
But the performance of existing lithium iron phosphate positive material still needs further to improve, and particularly in electric conductivity, shakes
Real density and stability etc..And LiFePO4 performance is not only influenced by the preparation process of its own, also before by its raw material
Drive the influence of body ferric phosphate.
Invention content
The phosphorus that electric conductivity is high, tap density is big, performance is stablized can be prepared the purpose of the present invention is to provide a kind of
Ferric phosphate presoma of sour iron lithium and preparation method thereof and the LiFePO4 and the system of the LiFePO4 prepared by the ferric phosphate
Preparation Method and the lithium battery including the LiFePO4.
In order to achieve the above object, scheme of the present invention is：
A kind of preparation method of the ferric phosphate presoma prepared particularly suitable for LiFePO4, the method includes following steps
Suddenly：
The step of preparing ferrous sulfate：To the aqueous solution containing a concentration of 30% sulfuric acid and 1-10% organic acids (with quality
Score meter) in add in and account for the reduced iron powder of aqueous solution quality 15wt%, the temperature of aqueous solution is controlled at 60-90 DEG C, so that reduction
Iron powder is reacted with solution, and the reaction time was controlled at 5-10 hours, and the first reaction solution is obtained after the completion of reaction, is reacted first
Liquid carries out high Magnetic filter (using magnetic very high magnetic filter filtering) to remove the iron ion of iron simple substance and high price, so as to
Obtain ferrous sulfate aqueous solution；
The organic acid is in lactic acid, malic acid, succinic acid, phytic acid or derivatives thereof (derivative for referring to aforementioned various acid)
At least one；Organic acid effect is control pH, control ferrous ion stability, meanwhile, certain organic acids (such as phytic acid spreads out
Biology) have the ratio that carbon in subsequent products of carbon source, phosphorus source, phosphorus are adjusted from molecular level concurrently, so as to optimize subsequent products
The effect of performance.
The step of preparing ferric phosphate process：The ferrous sulfate aqueous solution that previous step obtains is pumped into reaction kettle, to kettle
It is middle that the mixed liquor being made of ammonium persulfate, ammonium phosphate and nano-particle controlling agent, and ammonium persulfate, ferrous sulfate and phosphorus is added dropwise
The molar ratio of sour ammonium is 1.05:1:1；
Temperature is controlled at 60-80 DEG C, and adds in phosphoric acid control ph to controlling less than 3 to carry out precipitation reaction, is generally added in
The amount of phosphoric acid need 10% or so of ferrous sulfate quality；Precipitation reaction generally requires 5-8 hours, during this period to mixture
It is stirred mixing；In precipitation reaction terminal, mixture is carried out after Magnetic filter using obtaining filter cake after filter press press filtration,
Filter cake is rinsed to remove soluble impurity, then powder processed after spraying drying, obtains phosphoric acid iron product；To obtain high jolt ramming
Density using nanometer controlling agent control ferric phosphate granular size, effect be control carbon coating organic material and LiFePO4 it
Between interface connecting performance, improve carbon coating compactness, increase carbon LiFePO4 Dispersion on surface uniformity, improve carbon materials
Expect the degree of graphitization in carbonisation, and subtly adjust the ratio of carbon；The nano-particle controlling agent has following point
Subformula：
Wherein, R is the alkyl that carbon atom number is 1-18.
This method changes the object in ferrous sulfate solution by scene self-control ferrous sulfate and in wherein addition organic acid
Matter forms, also, nano-particle controlling agent is also added into the preparation section of ferric phosphate；Specifically：This nanometer of controlling agent
Nucleocapsid will be used as to connect substance, the pattern that ferric phosphate is controlled to be formed on one side bridges substance as nucleocapsid on one side, and connection is next
The glucide of cladding is walked, forms the structure of preliminary sugar-bridging-LiFePO4；That is, it can wrap up some organic substances
On LiFePO4 surface, wherein its residual silicon will be retained in nano-grade lithium iron phosphate, its residual silicone content is 0.001- after sintering
1%.
By the special role of nanometer controlling agent, pattern and microstructure to final product LiFePO4 carry out this method
It improves；Also, contain in the organic acid and nanometer controlling agent added during prepared by ferrous sulfate and prepared by ferric phosphate
Partial Elements can also enter in final product, so as to generate Beneficial Effect to the performance of final ferric phosphate.
Preferably, it is the phytic acid derivative with following molecular structural formula that the organic acid, which is phytic acid,：
Wherein, n 1-100.
The phytic acid derivative is prepared by the following method：By phytic acid and polyethylene glycol in molar ratio 1:1 mole
The hydrochloric acid of 1wt% is added in the reaction unit with water knockout drum than being added to as catalyst, is obtained after being reacted 8 hours in 90 DEG C
To the phytic acid derivative, substance is controlled using the derivative prepared as control pH and carbon source.Most preferably, addition is
5wt%.
The phytic acid derivative is in addition to having and iron ion ligand complex, the stability of control iron ion and control solution
Outside pH, also have the function of to control to adjust phosphorus source ratio and reduce nucleation energy in ferric phosphate synthesis.The phytic acid of aforementioned proportion exists
With more than 0.1% residual phosphorus rate and more than 0.1% Residual carbon after sintering, this is for adjusting in final LiFePO4 product
Ratio shared by P and C is helpful.
Preferably, the press filtration is completed using vertical type blotter press, and pressure is set as 10-200MPa during press filtration.
A kind of ferric phosphate presoma prepared for LiFePO4, the ferric phosphate is by side described in any one of the above embodiments
Prepared by method.
A kind of preparation method of LiFePO4, the described method comprises the following steps：
Dispensing：Using ferric phosphate prepared by the above method as source of iron, according to Li/Fe molar ratios 1-1.05 (preferably 1.03)
Ratio add in lithium carbonate, and add in the carbon source of 1-20wt% and the ball milling liquid of 10wt%, the carbon source is saccharide compound；
The ball milling liquid refers to that the mixed liquor containing particulate metal ion, the mixed liquor refers to containing at least two
Metal ion species mixed liquor, metal ion include：Na、Mg、Al、Ti、Zr、Mn、Nb、Ti；The metal ion wherein introduced includes
But it is not limited to soluble-salt and complex compound.
It prepares：Said mixture is subjected to ball milling, Ball-milling Time was controlled at 3-5 hours, and size controlling is in 0.1- after ball milling
2.5 micron；Then it is filtered with the filter press filtration of 800 mesh, the pressure of press filtration is 100-200MPa；It is spray-dried later, it will be dry
Powder after dry is kneaded, and mixing time is 2-4 hours, after being kneaded, is granulated to obtain granular precursor into tablet press machine,
Sintering：The particle being granulated is pushed into pre-burning in push plate vacuum sintering furnace, divides double sintering；First segment：Temperature is
150-300 DEG C, the time is 2-4 hours；Second segment：In the vacuum-sintering containing inert gas shielding on the basis of first segment sintering
Stove high temperature is sintered, and sintering temperature control is at 600-1000 DEG C, sintering time 8-15 hour, so that the abundant graphite of correlation organic matter
Change, then, be cooled to less than 50 DEG C come out of the stove or be cooled to room temperature after, LiFePO4 product is obtained after crushing.
During heat treatment, generated with water vapour and with precursor Fe3+The generation of the oxidizing gas of reduction, local gas
Concentration distribution has an impact quality.Therefore, it is necessary to pre-burnings, entirely sintering process will be divided into two sections of progress.
The C that the glucide used decomposites is can be under inactive gas atmosphere of the oxygen concentration below 0.1% by Fe3+
It is reduced to Fe2+Organic matter；It has the effect of adhesive concurrently, can be bonded together ferric phosphate, improves grinding efficiency, especially
It is the high sugar of viscosity.
The saccharide compound refers to there is the substance of following molecular structure：Cn(H2O)n, wherein n is 2-10；It can be with
As adhesive, reducing agent, sintering pattern controlling agent, progress is reacted with ferric phosphate, bonds LiFePO4, and control LiFePO4 is burnt
Tie pattern；That is, the sugar compounds as carbon source have reduction ferric phosphate, control iron phosphate grains size, nanometer is bonded
The effect of grain forming.The sugar compounds include：Sucrose, maltose, raffinose, especially stachyose, oligosaccharide.
During LiFePO4 is prepared, to burning out LiFePO4 product, Li, Fe, P and addition since most the step of
The molar ratio of matter-element element remains unchanged；Because in different processes, organic matter is all added, so C element molar ratio has
Change, in order to control remaining carbon in final product, it is necessary to the residual carbon amounts under each firing condition of measured in advance, so as in the first step
It is adjusted in the step of (i.e. the preparation of ferrous sulfate) and the second step the step of (i.e. the preparation of ferric phosphate).
In addition, in above-mentioned the third step (i.e. the preparation process of LiFePO4), preferably with respect to the LiFePO of generation4Addition
The polysaccharide of 1-20wt% when sugared additive amount is less than 1wt%, does not show additive effect；During more than 25wt%, it is impossible to effectively subtract
Few out-phase is precipitated.More preferably 2-15wt%.
Gained LiFePO in the present invention4The grain diameter of/C composite powders, before and after the third step, i.e., before the firing after
It is almost unchanged.Therefore, among the second step or before the third step, by adding aggegation of the organic adhesive by precursor
Grain grain size is adjusted to 0.3-30 μm, and the LiFePO of 0.3-30 μm of agglutinating particle grain size can be obtained after firing4。
More preferably, inert gas can be N2、Ar、H2O、CO2Or its mixed gas.
Preferably, described in the third step, the mixed liquor includes the carrier of dissolved metal ions, and this carrier removes
Have the function of outside dissolved metal ions also have the function of to disperse ferric phosphate, including：Ethyl alcohol, butanol, propyl alcohol, ethylene glycol,
Polyethylene glycol, polyvinyl alcohol, polyvinyl butyral, butanol, glycol ether, propylene glycol；Most preferably it is butanol.
A kind of LiFePO4, the LiFePO4 is adopted to be prepared with the aforedescribed process.
Preferentially, the grain size of the LiFePO4 is 0.3-30 μm；During less than 0.3 μm, anode packed density decline and with
The reactivity of electrolyte increases, so not preferably, controlled by sieving.
A kind of lithium battery, the lithium battery are to be prepared using above-mentioned LiFePO4 as positive electrode.
The LiFePO4 product addition element of the present invention is equably dissolved, and, with defect sturcture, is made by surface modification
The movement of electronics and lithium ion becomes easy；Its tap density is high, and compression forming volume density is 2.0g/cm3More than, therefore fill
Property improve, can improve the energy density of per unit volume.Fe3+Phase content is low, and impurity is few, and residual carbon amounts is 0.5-8wt%,
Impurity crystalline phase Li3PO4It measures as 5wt% hereinafter, crystallite dimension is 25-300nm, agglutinating particle grain size is 0.3-20 μm, is compressed into
Type volume density is 2.0-2.8g/cm3, charge/discharge cycle characteristics raising.It is controlled by being kneaded, squeezing out compacting, can be with
Think the LiFePO of the present invention4Powder residual carbon amounts is few, is aggregated between primary particle, and compression forming volume density is high.In addition, lithium and
The content of phosphorus is respectively 1-1.02, BET specific surface area 6-35m relative to the molar ratio of iron2/ g, residual carbon amounts are 0.5-
10wt%, crystallite dimension 25-300nm, agglutinating particle grain size are 0.3-20 μm, and compression forming volume density is 2.0-2.8g/
cm3, powder resistance rate is 20-200 Ω cm.
The present invention passes through the preparation process to LiFePO4 preparation process and raw material, the ferric phosphate for being used as LiFePO4 raw material
And the ingredient of raw material and initial raw material ferrous sulfate is improved, and make the electric conductivity of the LiFePO4 finally obtained, shake
Real density and stability obtain sufficient raising.
Description of the drawings
Fig. 1 a are the whole pattern SEM image of the ferric phosphate of embodiment 1；
Fig. 1 b are the nano particle pattern SEM image of the ferric phosphate spherical surface of embodiment 1；
Fig. 2 is the electrochemical performances of lithium iron phosphate figure of embodiment 1；
Fig. 3 is 3 maltose coated LiFePO 4 for lithium ion batteries TEM image of embodiment；
Fig. 4 is LiFePO4 SEM image；
Fig. 5 is LiFePO4 crystal structure figure.
Specific embodiment
In order to make those skilled in the art that the inventive concept of the present invention may be better understood, so as to the protection to the present invention
Range, which is made, more clearly to be limited, and the present invention is described in detail below in conjunction with the accompanying drawings.
A kind of preparation method of the ferric phosphate presoma prepared for LiFePO4, the described method comprises the following steps：
The step of preparing ferrous sulfate：It adds in and accounts for into the aqueous solution containing a concentration of 30% sulfuric acid and 1-10% organic acids
The reduced iron powder of aqueous solution quality 15wt% controls the temperature of aqueous solution at 60-90 DEG C, so that reduced iron powder carries out instead with solution
Should, the reaction time is controlled at 5-10 hour, and the first reaction solution is obtained after the completion of reaction, to the first reaction solution high Magnetic filter of progress with
Remove iron simple substance and the iron ion of high price, so as to obtain ferrous sulfate aqueous solution；
The organic acid is lactic acid, malic acid, succinic acid, phytic acid or derivatives thereof (refer to lactic acid, malic acid, succinic acid or
At least one of the derivative of phytic acid)；
The step of preparing ferric phosphate process：The ferrous sulfate aqueous solution that previous step obtains is pumped into reaction kettle, to kettle
It is middle that the mixed liquor being made of ammonium persulfate, ammonium phosphate and nano-particle controlling agent, and ammonium persulfate, ferrous sulfate and phosphorus is added dropwise
The molar ratio of sour ammonium is 1.05:1:1；
Temperature is controlled at 60-80 DEG C, and is added in phosphoric acid control ph and carried out precipitation reaction to less than 3, the phosphorus generally added in
The amount of acid needs 10% or so of ferrous sulfate quality；Precipitation reaction generally requires 5-8 hours, and mixture is carried out during this period
It is stirred；In precipitation reaction terminal, mixture is carried out to be pressed into filter cake using filter press after Magnetic filter, rinses to remove
Soluble impurity, powder processed after spraying drying, obtains phosphoric acid iron product；
The nano-particle controlling agent has following molecular structural formula：
Wherein, R is the alkyl that carbon atom number is 1-18.
Above-mentioned nanometer controlling agent will be used as nucleocapsid to connect substance, the pattern that ferric phosphate is controlled to be formed on one side, on one side as core
Shell structure bridges substance, connects the glucide of cladding in next step, forms the structure of preliminary sugar-bridging-LiFePO4；That is,
Some organic substances can be wrapped in LiFePO4 surface by it, and wherein its residual silicon will be retained in nano-grade lithium iron phosphate, sintering
Its residual silicone content is 0.001-1% afterwards.
More preferably, it is the phytic acid derivative with following molecular structural formula that the organic acid, which is phytic acid,：
Wherein, n 1-100.Most preferably, addition 5wt%.
The phytic acid derivative is prepared by the following method：By phytic acid and polyethylene glycol in molar ratio 1:1 mole
The hydrochloric acid of 1wt% is added in the reaction unit with water knockout drum than being added to as catalyst, is obtained after being reacted 8 hours in 90 DEG C
To the phytic acid derivative.
Phytic acid derivative is in addition to having with iron ion ligand complex, controlling the stability of iron ion and the pH of control solution
Outside, also have the function of to control to adjust phosphorus source ratio and reduce nucleation energy in ferric phosphate synthesis.The phytic acid of aforementioned proportion is being burnt
With more than 0.1% residual phosphorus rate and more than 0.1% Residual carbon after knot, this is for adjusting final LiFePO4 product phosphorus
It is helpful with the ratio of carbon.
A kind of ferric phosphate presoma prepared for LiFePO4, the ferric phosphate is by any of the above-described method
It prepares.
A kind of preparation method of LiFePO4, the described method comprises the following steps：
Dispensing：Using ferric phosphate prepared by the above method as source of iron, carbonic acid is added according to the ratio of Li/Fe molar ratios 1.03
Lithium, and the carbon source of 1-20wt% and the ball milling liquid of 10wt% are added in, the carbon source is saccharide compound；
The sugar compounds refer to there is the substance of following molecular structure：Cn(H2O)n, wherein n is 2-10；It includes：
Sucrose, maltose, raffinose, especially stachyose, oligosaccharide, the C that the glucide used decomposites is can be in oxygen concentration
By Fe under less than 0.1% inactive gas atmosphere3+It is reduced to Fe2+Organic matter；It can be used as adhesive, reducing agent, burning
Pattern controlling agent is tied, progress is reacted with ferric phosphate, bonds LiFePO4, control LiFePO4 sintering pattern；That is, conduct
The sugar compounds of carbon source have reduction ferric phosphate, control iron phosphate grains size, bond the molding effect of nano particle.
The ball milling liquid refers to, the mixed liquor containing particulate metal ion, the mixed liquor refer to contain there are two types of or
Two or more metal ion mixed liquors, metal ion include：Na、Mg、Al、Ti、Zr、Mn、Nb、Ti；The metal wherein introduced from
Son includes but not limited to soluble-salt and complex compound.
It prepares：Said mixture is subjected to ball milling, Ball-milling Time was controlled at 3-5 hours, and size controlling is in 0.1- after ball milling
2.5 micron；Then it is filtered with the filter of 800 mesh, dried powder is kneaded by spray drying, and mixing time is small for 2-4
When, after being kneaded, it is granulated into tablet press machine,
Sintering：The particle being granulated is pushed into pre-burning in vacuum sintering furnace, divides double sintering；First segment：Temperature is 150-
300 DEG C, the time is 2-4 hours；Second segment：On the basis of first segment sintering in the vacuum sintering furnace containing inert gas shielding
High temperature sintering, sintering temperature are controlled at 600-1000 DEG C, and sintering time 8-15 hours to be fully graphitized, then, is cooled to 50
It comes out of the stove below DEG C, LiFePO4 product is obtained after crushing.More preferably, inert gas can be N2、Ar、H2O、CO2Or its gaseous mixture
Body.
During heat treatment, generated with water vapour and with precursor Fe3+The generation of the oxidizing gas of reduction, local gas
Concentration distribution has an impact quality.Therefore, it is necessary to pre-burning, preferably calcined temperature is formal to fire temperature down to 250-500 DEG C or so
Degree is carried out with 400-800 DEG C of high temperature.Operation order between pre-burning and formal firing is not particularly limited.
During LiFePO4 is prepared, to burning out LiFePO4 product, Li, Fe, P and addition since most the step of
The molar ratio of matter-element element remains unchanged；And because in different processes, organic matter is all added, C element molar ratio has
Change, in order to control remaining carbon in final product, it is necessary to the residual carbon amounts under each firing condition of measured in advance, so as in the first step
It is adjusted in the step of (i.e. the preparation of ferrous sulfate) and the second step the step of (i.e. the preparation of ferric phosphate).
In addition, in above-mentioned the third step (i.e. the preparation process of LiFePO4), preferably with respect to the LiFePO of generation4Addition
The polysaccharide of 1-20wt% when sugared additive amount is less than 1wt%, does not show additive effect；During more than 25wt%, it is impossible to effectively subtract
Few out-phase is precipitated.More preferably 2-15wt%.
Gained LiFePO in the present invention4The grain diameter of/C composite powders, before and after the third step, i.e., before the firing after
It is almost unchanged.Therefore, among the second step or before the third step, by adding aggegation of the organic adhesive by precursor
Grain grain size is adjusted to 0.3-30 μm, and the LiFePO of 0.3-30 μm of agglutinating particle grain size can be obtained after firing4.Therefore, the side
Before method is additionally included in the third step or will carry out the third step, conductive carbon will be selected from, had Fe3+It is reduced to
Fe2+The electronics conductive auxiliary agent of the sugared lithium iron phosphate particles powder as generation of ability, the control for also serving as sintered particles size
Agent.
Preferably, described in the third step, the mixed liquor includes the carrier of dissolved metal ions, and this carrier removes
Have the function of outside dissolved metal ions also have the function of to disperse ferric phosphate；It includes：Ethyl alcohol, butanol, propyl alcohol, ethylene glycol,
Polyethylene glycol；Most preferably it is butanol.
A kind of LiFePO4, the ferric phosphate is adopted to be prepared with the aforedescribed process.
More preferably, the grain size of the LiFePO4 is 0.3-30 μm；During less than 0.3 μm, anode packed density decline and with
The reactivity of electrolyte increases, so not preferably, controlled by sieving.
A kind of lithium battery, the lithium battery are to be prepared using above-mentioned ferric phosphate as positive electrode.
Embodiment
The step of preparing ferrous sulfateDevice used includes：High magnetic filter, liner are polytetrafluoroethylene (PTFE), at a high speed
Mixing, the reactor of blender machine.High magnetic filter adjusts the obtained mixture purity of the step, and high-speed mixer is accelerated anti-
Speed is answered, and inner liner polytetrafluoroethylene reaction is the deep-etching for preventing sulfuric acid and organic acid.
The step of preparing ferric phosphate processDevice used includes：The reaction system of low level reaction kettle, high-order reaction kettle,
Pump, filter press, rinsing device, infrared drying stove, low level reactor.
The process of the preparation of LiFePO4Device used in (dispensing, preparation and the summation of sintering) includes：Ball mill, essence
Thin ball mill, high magnetic filter, 800 mesh filters, spray-drying installation, kneading device, tabletting extrusion device, vacuum-sintering
Stove, cloth bag pulverizer；Its obtained LiFePO4/ C tap densities can be controlled by mixing, extrusion pressure, bond amount
System.
Embodiment 1
The preparation of nanometer spherical iron phosphate：Iron of high-purity iron content more than 99.8% is put into and fills 30% sulfuric acid and 1%
The liner of the acid solution of phytic acid derivative (being counted using mass fraction) is heated to 95 DEG C as the reactive tank of polytetrafluoroethylene (PTFE), fully reacts
After 20 hours, pH value 3；Filtering, degaussing, impurity elimination obtain pure ferrous sulfate solution, a concentration of 170g/L, by sulfuric acid Asia
Ferrous solution 500L squeezes into enamel stills for air blowing, while by the diammonium hydrogen phosphate 72kg dissolved and oxidant ammonium persulfate 50kg 10
Stills for air blowing are added in minute, press filtration, degaussing, cleaning, decontamination fully after reaction obtain initial pure nano ferric phosphate slurry
Material, pH value 5.
It is 2.5, and fully dispersed that the acid ph value of initial slurry is adjusted with phosphoric acid, squeezes into reaction kettle, adds in 0.01% and receives
Rice controlling agent, is heated up to 95 DEG C, reacts 5 hours, and initial reactant ferric phosphate crystal grain is made to form orderly forming ball shaped nano crystalline substance,
Filtering, degaussing, rinsing, 150 DEG C of drying obtain nanometer spherical iron phosphate powder.
By nanometer spherical iron phosphate and lithium salts, (iron/phosphorus molar ratio is 1, lithium/phosphorus molar ratio 1.03:1) it, adds in and contains metal
Ball milling liquid 2kg, the glucose 46kg containing butanol of ion, addition is fully dispersed in the Scattered Kettle equipped with pure water or solvent, goes
Magnetic 3 hours, 800 turns of rotating speed squeeze into ball milling combination machine degaussing, ball milling 6 hours, and spray drying is put into tabletting comminutor tabletting two
Secondary granulation, sintering furnace is sintered 750 DEG C in nitrogen protection atmosphere, and the time is 12 hours, obtains lithium iron phosphate positive material.
Initial lithium iron phosphate positive material crushing (such as air-flow crushing or mechanical crushing) is classified, obtaining grain size is
The lithium iron phosphate positive material of 0.3-30 μm of suitable lithium ion cell positive coating performance.
Embodiment 2
The preparation of nanometer spherical iron phosphate：Iron of high-purity iron content more than 99.8% is put into and fills 30% sulfuric acid and 5%
The reactive tank of phytic acid derivative is heated to 90 DEG C, fully reaction 30 hours, pH value 3；Filtering, degaussing, impurity elimination obtain sulfuric acid Asia
Ferrous salt solution 400L is squeezed into enamel stills for air blowing, while the diammonium hydrogen phosphate 58kg and persulfuric acid that will have been dissolved by iron salt solutions
Ammonium 58kg added in stills for air blowing in 15 minutes, and press filtration cleaning decontamination fully after reaction obtains initial pure nano ferric phosphate
Slurry.
The acid ph value that initial slurry is adjusted using phosphoric acid is 2.8, and it is 1% to add in nanometer controlling agent, and fully dispersed, is beaten
Enter reaction kettle, be heated up to 95 DEG C, form initial ferric phosphate nanocrystalline, filtering rinsing, 110 DEG C of vacuum dryings obtain nanometer spherical
Ferric phosphate powder.
By nanometer spherical iron phosphate and lithium salts, (iron/phosphorus molar ratio is 1:1.01, lithium/phosphorus molar ratio 1.02:1), addition contains
Ball milling mixing liquid 2kg, the fruit threose 8kg for having metal ion are added in the Scattered Kettle equipped with pure water or solvent fully dispersed 4 hours,
900 turns of rotating speed, squeezes into ball milling combination machine, ball milling 5 hours, and spray drying is put into tabletting comminutor tabletting secondary granulation, lazy
Property atmosphere sintering furnace be sintered 750 DEG C, sintering time be 10 hours, obtain lithium iron phosphate positive material.
Lithium iron phosphate positive material is crushed (such as air-flow crushing or mechanical crushing) to be classified, obtains grain size as 0.3-30
μm suitable lithium-ion battery lithium iron phosphate positive electrode.
Embodiment 3
Iron sheet of high-purity iron content more than 99.8% is put into fill 30% sulfuric acid and 5% phytic acid derivative post poly- four
The reactive tank of vinyl fluoride is heated to 85 DEG C, fully reaction 38 hours, pH value 3；Filtering, degaussing, impurity elimination obtain pure ferrous iron
Ferrous salt solution 420L is squeezed into stills for air blowing, while the diammonium hydrogen phosphate 65kg dissolved and hydrogen peroxide 51kg are existed by salting liquid
Stills for air blowing are added in 25 minutes, press filtration cleaning decontamination fully after reaction obtains initial pure nano ferric phosphate slurry.
The acid ph value that initial slurry is adjusted with phosphoric acid is 3.0, adds in the nanometer controlling agent of 0.5wt%, and fully dispersed,
Reaction kettle is squeezed into, is heated up to 95 DEG C, forms initial ferric phosphate nanocrystalline, filtering rinsing, 120 DEG C of vacuum dryings obtain nanosphere
Shape ferric phosphate powder.
By nanometer spherical iron phosphate and lithium salts, (iron/phosphorus molar ratio is 0.98:1, lithium/phosphorus molar ratio 1.02:1) ball, is added in
It grinds mixed solution 3kg, maltose 8kg to add in the Scattered Kettle equipped with pure water or solvent fully dispersed 6 hours, 900 turns of rotating speed is beaten
Enter ball milling combination kettle, ball milling 8 hours, spray drying is put into tabletting comminutor tabletting secondary granulation, is burnt in inert atmosphere sintering furnace
750 DEG C of knot, time are 9 hours, obtain initial acid iron lithium anode material.
Initial carbon fusion nanometer spherical high magnification lithium iron phosphate positive material is crushed into (such as air-flow crushing or mechanical crushing)
Classification, the carbon for obtaining grain size as 0.3-30 μm of suitable lithium ion cell positive coating performance merge nanometer spherical high magnification ferric phosphate
Lithium anode material.
Embodiment 4
By high-purity iron content more than 99.8% iron be put into fill 30% sulfuric acid and 5% phytic acid derivative liner be poly- four
The reactive tank of vinyl fluoride is heated to 80 DEG C, fully reaction 50 hours, pH value 4；Filtering, degaussing, impurity elimination obtain pure ferrous salt
Ferrous salt solution 350L is squeezed into enamel stills for air blowing by solution, while by the diammonium hydrogen phosphate 70kg dissolved and hydrogen peroxide 38kg
Stills for air blowing were added in 30 minutes, press filtration cleaning decontamination fully after reaction obtains initial pure nano ferric phosphate slurry.With
The acid ph value that phosphoric acid adjusts initial slurry is 3.0, and fully dispersed, squeezes into reaction kettle, is heated up to 95 DEG C, makes initial ferric phosphate
Formed nanocrystalline, filtering rinsing, 120 DEG C of vacuum dryings obtain nanometer spherical iron phosphate powder.
By nanometer spherical iron phosphate and lithium salts, (iron/phosphorus molar ratio is 0.98:1, lithium/phosphorus molar ratio 1.03:1) ball, is added in
It grinds mixed solution 3kg, raffinose 8kg to add in the Scattered Kettle equipped with pure water or solvent fully dispersed 6 hours, 900 turns of rotating speed is beaten
Enter ball milling combination kettle, ball milling 8 hours, spray drying is put into tabletting comminutor tabletting secondary granulation, is burnt in inert atmosphere sintering furnace
750 DEG C of knot, time are 9 hours, obtain initial acid iron lithium anode material.
Initial lithium iron phosphate positive material is crushed into (such as air-flow crushing or mechanical crushing) classification, obtains grain size as 0.3-30
μm nanometer spherical high magnification lithium iron phosphate positive material.
Comparative example
The preparation of nanometer spherical iron phosphate：Iron of high-purity iron content more than 99.8% is put into the acid solution for filling 30% sulfuric acid
Liner be polytetrafluoroethylene (PTFE) reactive tank, be heated to 95 DEG C, fully reaction 20 hours after, pH value 5；Filtering, is gone at degaussing
It is miscellaneous to obtain pure ferrous sulfate solution, ferrous sulfate solution 500L is squeezed into enamel stills for air blowing, while the phosphoric acid that will have been dissolved
Hydrogen diammonium 72kg and oxidant ammonium persulfate 50kg added in stills for air blowing in 10 minutes, press filtration fully after reaction, degaussing, cleaning,
Decontamination obtains initial pure nano ferric phosphate slurry.
It is 2.5, and fully dispersed that the acid ph value of initial slurry is adjusted with phosphoric acid, squeezes into reaction kettle, is heated up to 95 DEG C, instead
It answers 5 hours, initial reactant ferric phosphate crystal grain is made to form orderly forming ball shaped nano brilliant, filtering, degaussing, rinsing, 150 DEG C
Drying obtains nanometer spherical iron phosphate powder.
By nanometer spherical iron phosphate and lithium salts, (iron/phosphorus molar ratio is 1, lithium/phosphorus molar ratio 1.03:1) it, adds in and contains metal
The ball milling liquid 2kg containing butanol, the sugar 46kg of ion, addition is fully dispersed in the Scattered Kettle equipped with pure water or solvent, degaussing 3 is small
When, 800 turns of rotating speed squeezes into ball milling combination machine degaussing, ball milling 6 hours, spray drying, is put into that tabletting comminutor tabletting is secondary to make
Grain, sintering furnace is sintered 750 DEG C in nitrogen protection atmosphere, and the time is 12 hours, obtains lithium iron phosphate positive material.
Initial lithium iron phosphate positive material crushing (such as air-flow crushing or mechanical crushing) is classified, obtaining grain size is
The lithium iron phosphate positive material of 0.3-30 μm of suitable lithium ion cell positive coating performance.
Lithium iron phosphate positive material obtained by above-described embodiment 1-4 and comparative example is fabricated to lithium by identical preparation condition
Battery simultaneously carries out dependence test, and test result is shown in Table 1.
Table 1
Claims (10)
1. a kind of preparation method of ferric phosphate, which is characterized in that the described method comprises the following steps：
The step of preparing ferrous sulfate：It is added in into the aqueous solution containing 30% sulfuric acid and 1-10% organic acids and accounts for aqueous solution quality
The reduced iron powder of 15wt% reacts 5-10 hours in 60-90 DEG C, through excessively high Magnetic filter after the completion of reaction, obtains ferrous sulfate water
Solution；
The organic acid is lactic acid, malic acid, succinic acid, phytic acid or lactic acid, in the derivative of malic acid, succinic acid, phytic acid
It is at least one；
The step of preparing ferric phosphate process：The ferrous sulfate aqueous solution that previous step obtains is pumped into chemical reaction kettle, to
The mixed liquor being made of ammonium persulfate, ammonium phosphate, nano-particle controlling agent, ammonium persulfate, ferrous sulfate and phosphoric acid are added dropwise in kettle
The molar ratio of ammonium is 1.05:1:1；
The temperature of mixed solution is controlled at 60-80 DEG C, and adds in phosphoric acid control ph to 3 hereinafter, and being stirred 5-8
Hour carries out precipitation reaction；After reaction, Magnetic filter is removed to the mixture after reaction, spraying, which is dried, after press filtration, rinsing obtains
Phosphoric acid iron product；
The nano-particle controlling agent has following molecular structural formula：
Wherein, R is the alkyl that carbon atom number is 1-18.
2. according to the method described in claim 1, it is characterized in that, the organic acid is the phytic acid with following molecular structural formula
Derivative：
Wherein, n 1-100.
3. according to the method described in claim 2, it is characterized in that, the phytic acid derivative is prepared by the following method：
By phytic acid and polyethylene glycol in molar ratio 1:1 molar ratio is added in the reaction unit with water knockout drum, adds in 1wt%
Hydrochloric acid, in 90 DEG C reaction 8 hours after obtain the phytic acid derivative.
4. according to the method described in claim 2, it is characterized in that, the addition of the phytic acid derivative is 5wt%.
5. a kind of ferric phosphate presoma prepared for LiFePO4, which is characterized in that the ferric phosphate is will by such as right
Ask prepared by 1-4 any one of them method.
6. a kind of preparation method of LiFePO4, which is characterized in that the described method comprises the following steps：
Dispensing：Using the ferric phosphate described in claim 5 as source of iron, the molar ratio according to Li/Fe is 1-1.05 addition lithium carbonates,
And the carbon source of 10-20wt% and the ball milling liquid of 10wt% are added in, the carbon source is conductive carbon or saccharide compound；
The ball milling liquid is containing at least two metal ion mixed liquors, and the metal ion includes：Na、Mg、Al、Ti、Zr、
Mn, Nb and Ti；
It prepares：Ball milling is carried out to said mixture, Ball-milling Time 3-5 hours, 800 mesh filter press filtrations filter after the completion of ball milling,
Then it is spray-dried, is granulated after being kneaded 2-4 hours later, obtains granular precursor；
Sintering：Granular precursor is placed in vacuum sintering furnace, 150-300 DEG C of pre-burning 2-4 hours, then in inert gas shielding
Under the conditions of carry out high temperature sintering, 600-1000 DEG C of sintering temperature, time 8-15 hour, crushed after being cooled to room temperature, obtain phosphoric acid
Iron lithium product.
7. according to the method described in claim 6, it is characterized in that, the mixed liquor includes the carrier of dissolved metal ions, institute
Carrier is stated to include：Ethyl alcohol, propyl alcohol, ethylene glycol, polyethylene glycol, polyvinyl alcohol, polyvinyl butyral, butanol, glycol ether, the third two
Alcohol ether.
8. a kind of LiFePO4, which is characterized in that the LiFePO4 is to use such as claim 6-7 any one of them methods
It prepares.
9. LiFePO4 according to claim 8, which is characterized in that the grain size of the LiFePO4 is by sieving and controlled
It is made as 0.3-30 μm.
10. a kind of lithium battery, which is characterized in that the lithium battery is as just using the LiFePO4 described in claim 8 or 9
Pole material preparation forms.
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| CN109205586B (en) * | 2018-09-07 | 2019-12-10 | 高延敏 | Industrialized lithium iron phosphate manufacturing method and lithium iron phosphate composite material prepared by same |
| CN111146439B (en) * | 2018-11-06 | 2021-10-15 | 北京泰丰先行新能源科技有限公司 | Preparation method of lithium iron phosphate cathode material |
| CN110642235B (en) * | 2019-10-25 | 2022-03-01 | 湖北万润新能源科技股份有限公司 | Preparation method of core-shell structure battery-grade anhydrous iron phosphate |
| CN114906831B (en) | 2021-02-09 | 2024-05-31 | 锂源(深圳)科学研究有限公司 | Preparation method of lithium iron phosphate, lithium iron phosphate material and lithium ion battery |
| CN115367721A (en) * | 2021-05-19 | 2022-11-22 | 中国科学院过程工程研究所 | Method for preparing iron phosphate from iron-containing waste acid liquor |
| CN113942988B (en) * | 2021-11-22 | 2023-09-12 | 青岛九环新越新能源科技股份有限公司 | Ferric phosphate and preparation method thereof |
| CN114057176B (en) * | 2021-11-22 | 2023-09-19 | 青岛九环新越新能源科技股份有限公司 | Lithium iron phosphate and preparation method and application thereof |
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