CN107324306B - A kind of nano-grade lithium iron phosphate and preparation method thereof - Google Patents
A kind of nano-grade lithium iron phosphate and preparation method thereof Download PDFInfo
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Abstract
A kind of nano-grade lithium iron phosphate and preparation method thereof, is related to technical field of lithium batteries.The preparation method of nano-grade lithium iron phosphate includes: to mix nano-sheet ferric phosphate, lithium source, organic solvent, carboxylic acid sources and surfactant to carry out wet ball grinding formation mixture；Under the protection of inert gas; by mixture under conditions of temperature is 120-200 DEG C after heat preservation 40-100min; it is warming up to 680-720 DEG C of heat preservation 10-13h; lithium source is lithium carbonate, lithium hydroxide or lithium oxalate; organic solvent is ethylene glycol, nano-sheet ferric phosphate, lithium ion, organic solvent, carboxylic acid and surfactant molar ratio be 1:1-1.05:1-3:0.2-1:0.005-0.05.Its simple process, and the good LiFePO4 of chemical property can be prepared.A kind of nano-grade lithium iron phosphate is prepared by the preparation method of above-mentioned nano-grade lithium iron phosphate.It has the characteristics that conductivity is preferable.
Description
Technical field
The present invention relates to technical field of lithium batteries, and in particular to a kind of nano-grade lithium iron phosphate and preparation method thereof.
Background technique
Ferric phosphate lithium cell refers to the lithium ion battery for using LiFePO4 as positive electrode.In LiFePO4 crystal
P-O key is firm, it is difficult to decompose, even if in high temperature or structural breakdown fever or will not be formed strong as cobalt acid lithium when overcharging
Oxidizing substance, therefore possess good safety.Ferric phosphate lithium cell does not contain any metal and rare metal, nontoxic, nothing
Pollution, it is very environmentally friendly.In addition ferric phosphate lithium cell have many advantages, such as high-temperature behavior is good, capacity is big, memory-less effect, it is light-weight and
It is widely used.
The preparation method of LiFePO4 mainly has high temperature solid-state method, liquid-phase coprecipitation, sol-gel method, hydro-thermal method etc..
Using high temperature solid-state method, usually after mixing by organic carbon source, phosphorus source and source of iron, it is fired into LiFePO4 at high temperature.
But the electrochemical performances of lithium iron phosphate being usually prepared is poor.
Summary of the invention
The purpose of the present invention is to provide a kind of preparation method of nano-grade lithium iron phosphate, this preparation method simple process, and
The good nano-grade lithium iron phosphate of chemical property can be prepared.
Another object of the present invention is to provide a kind of nano-grade lithium iron phosphate, have the characteristics that conductivity is preferable.
The present invention solves its technical problem and adopts the following technical solutions to realize.
A kind of preparation method of nano-grade lithium iron phosphate, including following preparation step:
Nano-sheet ferric phosphate, lithium source, organic solvent, carboxylic acid sources and surfactant are mixed progress wet ball grinding to be formed
Mixture；Under the protection of inert gas, mixture after heat preservation 40-100min, is risen under conditions of temperature is 120-200 DEG C
Temperature is to 680-720 DEG C of heat preservation 10-13h.Lithium source includes lithium carbonate, lithium hydroxide or lithium oxalate, and organic solvent includes ethylene glycol, is received
Rice sheet-form iron phosphate, the lithium ion in lithium source, organic solvent, the carboxylic acid in carboxylic acid sources and surfactant molar ratio be 1:
1-1.05:1-3:0.2-1:0.005-0.05。
A kind of nano-grade lithium iron phosphate is prepared by the preparation method of above-mentioned nano-grade lithium iron phosphate.
A kind of beneficial effect of nano-grade lithium iron phosphate of the embodiment of the present invention and preparation method thereof is: nano-grade lithium iron phosphate
In preparation method, using ethylene glycol as organic solvent, flake nano ferric phosphate, lithium source and carboxylic acid, surfactant are dissolved in molten
In agent, wet ball grinding is first carried out, flake nano ferric phosphate, lithium source and carboxylic acid, surfactant is sufficiently mixed in organic solvent
Dissolution is closed, partial size becomes smaller, and is conducive to the progress of reaction.Flake nano ferric phosphate, lithium source, organic solvent and carboxylic acid, surface-active
Dosage form at mixture temperature be 120-200 DEG C under conditions of heat preservation 40-100min after, can fully be fused into flow-like
State, because its flow regime can interpenetrate between different substances.After then heating to 680-720 DEG C of heat preservation 10-13h, by
The complexing peptizaiton of carboxylic acid in carboxylic acid sources, flake nano ferric phosphate and lithium source occur complex reaction and generate nano ferric phosphate
Lithium.Lithium source is provided by lithium carbonate, lithium hydroxide or lithium oxalate, does not introduce other impurities.A kind of nano-grade lithium iron phosphate, by above-mentioned
The preparation method of nano-grade lithium iron phosphate be prepared.It has the advantages that conductivity is preferable.
Specific embodiment
It in order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below will be in the embodiment of the present invention
Technical solution be clearly and completely described.The person that is not specified actual conditions in embodiment, according to normal conditions or manufacturer builds
The condition of view carries out.Reagents or instruments used without specified manufacturer is the conventional production that can be obtained by commercially available purchase
Product.
A kind of nano-grade lithium iron phosphate of the embodiment of the present invention and preparation method thereof is specifically described below.
A kind of preparation method of nano-grade lithium iron phosphate, including following preparation step:
Nano-sheet ferric phosphate, lithium source, organic solvent, carboxylic acid sources and surfactant are mixed progress wet ball grinding to be formed
Mixture.Lithium source includes lithium carbonate, lithium hydroxide or lithium oxalate, does not introduce other impurities.Organic solvent includes ethylene glycol.It receives
Rice sheet-form iron phosphate, the lithium ion in lithium source, organic solvent, the carboxylic acid in carboxylic acid sources and surfactant molar ratio are 1:1-
1.05:1-3:0.2-1:0.005-0.05。
Organic solvent includes ethylene glycol, in organic solvent by the dissolution of ferric phosphate, lithium source and carboxylic acid sources, first carries out wet process ball
Ferric phosphate, lithium source and carboxylic acid sources are sufficiently mixed dissolution by mill in organic solvent, and each component partial size becomes smaller, and are conducive to reaction
It carries out.
Then under the protection of inert gas, mixture is kept the temperature into 40-100min under conditions of temperature is 120-200 DEG C
Afterwards, it is warming up to 680-720 DEG C of heat preservation 10-13h.
In the preparation method of nano-grade lithium iron phosphate, using ethylene glycol as organic solvent, by flake nano ferric phosphate, lithium source and carboxylic
Acid source, surfactant dissolution in a solvent, first carry out wet ball grinding, by flake nano ferric phosphate, lithium source and carboxylic acid sources, surface
Activating agent is sufficiently mixed dissolution in organic solvent.Flake nano ferric phosphate, lithium source, organic solvent and carboxylic acid sources, surface-active
Dosage form at mixture temperature be 120-200 DEG C under conditions of heat preservation 40-100min after, can fully be fused into flow-like
State, because its flow regime can interpenetrate between different substances.After then heating to 680-720 DEG C of heat preservation 10-13h, by
The complexing peptizaiton of carboxylic acid in carboxylic acid sources, flake nano ferric phosphate and lithium source occur complex reaction and generate nano ferric phosphate
Lithium.
Further, carboxylic acid sources include being provided by oxalic acid and at least one of citric acid.In the present embodiment, carboxylic acid sources are equal
It, in other embodiments, can be using the mixture of oxalic acid and citric acid as carboxylic acid sources only with one kind.Further, table
Face activating agent includes at least one of cetyl trimethylammonium bromide, polysorbate and alkyl phenol polyoxyethylene ether.Wherein,
Polysorbate, nickname Tween 80.Alkyl phenol polyoxyethylene ether is also known as OP-10.
In an embodiment of the present invention, nano-grade lithium iron phosphate is used using nano-sheet ferric phosphate as precursor material.Phosphoric acid
Structure, pattern and the property of iron will have a direct impact on the performance of ferric phosphate lithium cell.In the preparation method of ferric phosphate, if reacting
The presence for having brought foreign ion, especially acid ion in system into can greatly reduce the performance of LiFePO4.
Further, nano-sheet ferric phosphate is mainly made by following steps: after source of iron, phosphorus source, complexing agent are mixed, being delayed
The slow hydrogen peroxide that is added reacts 100-400min at a temperature of 70-100 DEG C, and the pH value of reaction system is 1.2-4, the quality of hydrogen peroxide
Concentration is 20-30%, wherein the molar ratio of ferro element, phosphate radical, complexing agent and hydrogen peroxide in reaction system is 1:1-1.6:
0.01-0.05:0.5-2.0。
Source of iron, phosphorus source, complexing agent and hydrogen peroxide are 70-100 DEG C in temperature, and network occurs in the reaction system that pH value is 1-4
It closes and reacts available ferric phosphate crystal seed.During hydrogen peroxide is slowly added to, ferric phosphate is the process increasingly generated, later period
The ferric phosphate of generation ultimately generates the ferric phosphate of sheet using ferric phosphate crystal seed as nucleus growth.Entire reaction system can press down at acidity
Fe in ferric phosphate processed3+Hydrolysis occurs, ensure that the product quality of final ferric phosphate.Preferably, the pH value of reaction system
For 2-3, the pH value of reaction system is adjusted by the way that phosphoric acid is added.
In addition, the reaction time is 100-400min, there is the sufficient time to make ferric phosphate ageing, growth.It is generated in reaction
During ferric phosphate, excessive hydrogen peroxide enables to ferrous ion to be all oxidized to Fe3+, and avoid having Asia in product
The presence of iron ion and the performance for influencing ferric phosphate.
Preferably, source of iron includes by least one of ferric acetate, ferrous acetate, ferrous phosphate and biphosphate ferrous iron
It provides.Phosphorus source includes being provided by least one of ferrous phosphate, biphosphate ferrous iron and phosphoric acid.In entire reaction process,
Without introducing other impurities ion, such as acid ion, sodium ion, potassium ion and chloride ion.When selection ferrous phosphate or phosphorus
When acid dihydride ferrous iron, phosphorus source and source of iron can be both functioned simultaneously as.
Preferably, the molar ratio of ferro element, phosphate radical, complexing agent and hydrogen peroxide is 1:1.1-1.5:0.02-0.04:0.8-
1.5.The proportional region is the creative thinking and empirical preferred value by inventor, is 1:1.1- using molar ratio
Ferro element, phosphate radical, the complexing agent of 1.5:0.02-0.04:0.8-1.5 is reacted with hydrogen peroxide, can obtain better quality
Sheet-form iron phosphate.
Further, in an embodiment of the present invention, ferric acetate is mainly made by following preparation method: by carbonyl iron dust with
Acetic acid, hydrogen peroxide react at a temperature of being blended in 60-80 DEG C.Carbonyl iron dust is anti-at high temperature under high pressure with iron by carbon monoxide
It answers, generates iron pentacarbonyl grease, obtain product after low pressure separates.Carbonyl iron dust has the characteristics that granularity is small, active big,
Energy can quickly be absorbed and make rapid reaction.Carbonyl iron dust in onion it is spherical, granularity be 10 μm hereinafter, carbonyl iron dust with
Acetic acid 60-80 DEG C at a temperature of can quickly react and generate ferrous acetate, ferrous acetate reacts under the action of hydrogen peroxide
Ferric acetate is generated, since carbonyl iron dust activity is higher, reaction speed is very fast.It should be noted that in other embodiments,
The ferric acetate first prepared can be used.Ferric acetate is easier to hydrolyze, so in the embodiment of the present invention, ferric acetate is all according to saying
Method in bright book specific embodiment is ready-to-use.
Further, complexing agent includes at least one of oxalic acid, acetic acid and citric acid.Complexing agent uses oxalic acid, acetic acid
And citric acid, the relatively good processing of the ion of introducing will not bring other impurities ion into system.
Further, in above-mentioned preparation step, further include the steps that in the reaction system be added dispersing agent, dispersing agent with
The molar ratio of ferrous phosphate is 0.0005-0.001:1.
Dispersing agent is added in reaction system, each component in the uniform dispersion reaction system of dispersing agent energy, so that each component
Between be uniformly dispersed, be conducive to the progress of reaction, the ferric phosphate that final reaction obtains is functional.Preferably, dispersing agent includes
At least one of polyethylene glycol, polyethylene wax and alcohol ether carboxylate.In some embodiments of the invention, it joined dispersing agent
In embodiment, one of which only joined.In other embodiments, dispersing agent is added, can be polyethylene glycol and polyethylene wax
Combination, the combination of polyethylene wax and alcohol ether carboxylate, the combination of polyethylene glycol and alcohol ether carboxylate, be also possible to three and all add
Enter.
A kind of nano-grade lithium iron phosphate is prepared by the preparation method of above-mentioned nano-grade lithium iron phosphate.It is with vibration density
Spend higher, the preferable advantage of conductivity.
Feature and performance of the invention are described in further detail with reference to embodiments.
Embodiment 1
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferrous acetate, ferrous phosphate, oxalic acid are mixed in reaction kettle, pair that mass concentration is 20% is then slowly added into
Oxygen water, add phosphoric acid adjust reaction system pH value to 2, then 80 DEG C at a temperature of react 300min.Wherein, reactant
The molar ratio of ferrous ion, phosphate radical, oxalic acid and hydrogen peroxide in system is 1:1.2:0.03:0.8.After the reaction was completed by reactant
System is filtered, and washs the product being obtained by filtration to obtain sediment with EtOH Sonicate, will obtain nanometer sheet after drying precipitate
Shape ferric phosphate.
Nano-sheet ferric phosphate, lithium hydroxide, ethylene glycol, the oxalic acid and 16 for being 1:1:2:0.4:0.005 by molar ratio
Alkyl trimethyl ammonium bromide mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, in temperature
After degree keeps the temperature 70min under conditions of being 150 DEG C, it is warming up to 680 DEG C of heat preservation 13h.
Embodiment 2
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferric acetate, ferrous phosphate, acetic acid are mixed in reaction kettle, the dioxygen that mass concentration is 25% is then slowly added into
Water, add phosphoric acid adjust reaction system pH value to 3, then 100 DEG C at a temperature of react 100min.Wherein, reactant
The molar ratio of iron ion, phosphate radical, acetic acid and hydrogen peroxide in system is 1:1:0.02:0.5.After the reaction was completed by reaction system into
Row filtering, washs the product being obtained by filtration to obtain sediment with EtOH Sonicate, nano-sheet phosphorus will be obtained after drying precipitate
Sour iron.
By nano-sheet ferric phosphate, lithium carbonate, polyalcohol and citric acid that molar ratio is 1:0.51:1:0.6:0.01, poly-
The mixing of sorb ester carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, is 120 DEG C in temperature
Under the conditions of keep the temperature 100min after, be warming up to 685 DEG C of heat preservation 13h.
Embodiment 3
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferric acetate, ferrous acetate, phosphoric acid, citric acid are mixed in reaction kettle, being then slowly added into mass concentration is
30% hydrogen peroxide, add phosphoric acid adjust reaction system pH value to 1.2, then 70 DEG C at a temperature of react 400min.
Wherein, the molar ratio of the iron ion in reaction system, phosphate radical, acetic acid and hydrogen peroxide is 1:1.5:0.05:1.8.Reaction is completed
Reaction system is filtered afterwards, washs the product being obtained by filtration to obtain sediment with EtOH Sonicate, after drying precipitate
Obtain nano-sheet ferric phosphate.
By nano-sheet ferric phosphate, lithium carbonate, polyalcohol and citric acid that molar ratio is 1:0.525:1:0.2:0.02, poly-
The mixing of sorb ester carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, is 130 DEG C in temperature
Under the conditions of keep the temperature 90min after, be warming up to 690 DEG C of heat preservation 12h.
Embodiment 4
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Biphosphate ferrous iron, phosphoric acid, citric acid are mixed in reaction kettle, being then slowly added into mass concentration is 28%
Hydrogen peroxide, add phosphoric acid adjust reaction system pH value to 3, then 75 DEG C at a temperature of react 340min.Wherein, it reacts
The molar ratio of ferrous ion, phosphate radical, citric acid and hydrogen peroxide in system is 1:1.1:0.03:1.2.It after the reaction was completed will be anti-
It answers system to be filtered, washs the product being obtained by filtration to obtain sediment with EtOH Sonicate, will be received after drying precipitate
Rice sheet-form iron phosphate.
Nano-sheet ferric phosphate, lithium oxalate, polyalcohol and oxalic acid, the alkyl phenol for being 1:0.52:3:1:0.05 by molar ratio
Polyoxyethylene ether mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, is 180 in temperature
After keeping the temperature 60min under conditions of DEG C, it is warming up to 695 DEG C of heat preservation 12h.
Embodiment 5
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferrous acetate, phosphoric acid, citric acid are mixed in reaction kettle, the dioxygen that mass concentration is 26% is then slowly added into
Water, add phosphoric acid adjust reaction system pH value to 4, then 90 DEG C at a temperature of react 150min.Wherein, reaction system
In ferrous ion, phosphate radical, citric acid and hydrogen peroxide molar ratio be 1:1.6:0.04:2.After the reaction was completed by reaction system
It is filtered, washs the product being obtained by filtration to obtain sediment with EtOH Sonicate, nano-sheet will be obtained after drying precipitate
Ferric phosphate.
Nano-sheet ferric phosphate, lithium oxalate, polyalcohol and oxalic acid, the alkyl for being 1:0.5:1.5:0.5:0.02 by molar ratio
Phenol polyethenoxy ether mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, is in temperature
After keeping the temperature 80min under conditions of 165 DEG C, it is warming up to 700 DEG C of heat preservation 11h.
Embodiment 6
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferric acetate, phosphoric acid, oxalic acid, alcohol ether carboxylate are mixed in reaction kettle, being then slowly added into mass concentration is
23% hydrogen peroxide, add phosphoric acid adjust reaction system pH value to 2, then 85 DEG C at a temperature of react 280min.Its
In, the molar ratio of iron ion, phosphate radical, oxalic acid, hydrogen peroxide and alcohol ether carboxylate in reaction system is 1:1.1:0.01:1.5:
0.0008.Reaction system is filtered after the reaction was completed, washs the product being obtained by filtration to obtain sediment with EtOH Sonicate,
Nano-sheet ferric phosphate will be obtained after drying precipitate.
By molar ratio be 1:0.51:1.8:0.7:0.03 nano-sheet ferric phosphate, lithium oxalate, polyalcohol and citric acid,
Alkyl phenol polyoxyethylene ether mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, in temperature
After degree keeps the temperature 85min under conditions of being 180 DEG C, it is warming up to 705 DEG C of heat preservation 11h.
Embodiment 7
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Ferrous acetate, biphosphate ferrous iron, phosphoric acid, citric acid and polyethylene wax are mixed in reaction kettle, then slowly
The hydrogen peroxide that mass concentration is 25% is added, adds the pH value of phosphoric acid adjusting reaction system to 2.5, then in 80 DEG C of temperature
Lower reaction 300min.Wherein, the molar ratio of the ferrous ion in reaction system, phosphate radical, citric acid, hydrogen peroxide and polyethylene wax
For 1:1.3:0.02:1:0.0005.Reaction system is filtered after the reaction was completed, the product EtOH Sonicate that will be obtained by filtration
Washing obtains sediment, and nano-sheet ferric phosphate will be obtained after drying precipitate.
Nano-sheet ferric phosphate, lithium oxalate, polyalcohol and citric acid, the table for being 1:0.5:1.2:0.3:0.04 by molar ratio
Face activating agent (cetyl trimethylammonium bromide, polysorbate) mixing carries out wet ball grinding and forms mixture, and mixture is set
Under the protection of inert gas, under conditions of temperature is 185 DEG C after heat preservation 80min, it is warming up to 710 DEG C of heat preservation 10h.
Embodiment 8
A kind of nano-grade lithium iron phosphate, the preparation method of the nano-grade lithium iron phosphate include following preparation step:
Biphosphate ferrous iron, phosphoric acid, citric acid and polyethylene glycol are mixed in reaction kettle, it is dense to be then slowly added into quality
Degree be 27% hydrogen peroxide, add phosphoric acid adjust reaction system pH value to 1.5, then 85 DEG C at a temperature of react
320min.Wherein, the molar ratio of the ferrous ion in reaction system, phosphate radical, citric acid, hydrogen peroxide and polyethylene glycol is 1:
1.5:0.03:1.4:0.001.Reaction system is filtered after the reaction was completed, the product being obtained by filtration is washed with EtOH Sonicate
It washs to obtain sediment, nano-sheet ferric phosphate will be obtained after drying precipitate.
Nano-sheet ferric phosphate, lithium hydroxide, polyalcohol and citric acid, the table for being 1:1:2.5:0.9:0.01 by molar ratio
Face activating agent (alkyl phenol polyoxyethylene ether, polysorbate) mixing carries out wet ball grinding and forms mixture, mixture is placed in lazy
Property gas protection under, temperature be 160 DEG C under conditions of heat preservation 70min after, be warming up to 720 DEG C of heat preservation 10h.
Comparative example 1
Quantitative lithium carbonate, ferric phosphate and glucose are weighed by the molar ratio of 0.5:1:0.125, then weighs the third of 15mL
Ketone pours into mortar, is quickly ground with pestle；After slurry is milled to dry powder, 15mL acetone soln is added again and repeats
Above-mentioned steps.
By the siccative after grinding through the horizontal flakelet for being compacted into 2mm thickness to roll squeezer, then sheet material is transferred to
In ball grinder, 10mL alcohol is added and carries out ball milling dispersion 1 hour.Then gained slurry is placed in 80 DEG C of bakings using stainless steel pallet
2h is toasted in case, finally the powder after drying is passed through, secondary tabletting is carried out to roll squeezer, be placed in tube furnace, leads to nitrogen protection,
4h is sintered under the conditions of 750 DEG C.
Comparative example 2
A kind of LiFePO4, the preparation method of the LiFePO4 include following preparation step:
27g iron powder is weighed in reaction kettle, 1230mL distilled water is added after 94g phosphoric acid is added, is stirred continuously down and is warming up to
70 DEG C, 2h is reacted, ferrous phosphate is filtered to obtain.Then it is molten that the hydrogen peroxide that 9g mass fraction is 30% is added into ferrous phosphate
Liquid continuously adds 9.0g ethanol solution, is stirred continuously and is warming up to 50 DEG C, reacts 4h, ferric phosphate crude product is obtained by filtration.Then it uses
Ferric phosphate crude product is followed by stirring and washing in 50 DEG C of distilled water 180g, filters after repeated washing 2 times, and filtered precipitating is placed in
In 65 DEG C of baking oven after dry 6h, phosphoric acid iron product is obtained.
Nano-sheet ferric phosphate, lithium hydroxide, ethylene glycol, the oxalic acid and 16 for being 1:1:2:0.4:0.005 by molar ratio
Alkyl trimethyl ammonium bromide mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, in temperature
After degree keeps the temperature 70min under conditions of being 150 DEG C, it is warming up to 680 DEG C of heat preservation 13h.
Comparative example 3
A kind of LiFePO4, the preparation method of the LiFePO4 include following preparation step:
In 1m3Reaction kettle in be added 150kg water, 27.5g ferrous sulfate heptahydrate, dissolve solid under stirring, be added
The hydrogen peroxide that 9kg concentration is 28% is added in 12.5kg phosphoric acid in 1h, and adjustment solution temperature is 55 DEG C, is added with stirring concentration
For 10% sodium carbonate liquor 47kg, flow velocity 10L/h, 95 DEG C of heat preservation 6h are then heated to, solution is introduced 6 while heat preservation
Soluble inorganic salt is separated in grade cyclone, while product forms the particle of spheroidal in cyclone high speed eddy flow；It isolates
Product be dried up to ferric phosphate.
Nano-sheet ferric phosphate, lithium hydroxide, ethylene glycol, the oxalic acid and 16 for being 1:1:2:0.4:0.005 by molar ratio
Alkyl trimethyl ammonium bromide mixing carries out wet ball grinding and forms mixture, mixture is placed under the protection of inert gas, in temperature
After degree keeps the temperature 70min under conditions of being 150 DEG C, it is warming up to 680 DEG C of heat preservation 13h.
Test example
Experimental subjects: the LiFePO4 that embodiment 1-8 and comparative example 1-3 are prepared.
Experiment test:
(1) partial size is tested: measuring it to the obtained LiFePO4 of embodiment 1-8 and comparative example 1-3 by laser particle size method
The average grain diameter of product, result are recorded in table 1.
(2) tap density: with reference to GB/T 5162-2006 (measurement of metal powder tap density) to embodiment 1-8 and right
The LiFePO4 that ratio 1-3 is obtained carries out the measurement of tap density.Its result is recorded in table 1.
(3) battery assembly and test: preparing electrode using coating method, with n-methyl-2-pyrrolidone (MNP) for solvent,
LiFePO is weighed respectively by certain mass ratio4/ C positive electrode material, acetylene black and polytetrafluoroethylene (PTFE) (PVDF), coat after mixing
On aluminium foil, 120 DEG C of vacuum drying.2032 type button cell systems are assembled into the vacuum glove box full of high-purity argon gas,
Carry out charge-discharge test, charging/discharging voltage 2.0-4.0V.It will discharge after 0.2C first discharge specific capacity and cycle charge-discharge 5 times
The test result of specific capacity is recorded in table 1.
The test result of the LiFePO4 of table 1 embodiment 1-8 and comparative example 1-3
As can be seen from Table 1, the even particle size distribution of the nano-grade lithium iron phosphate of 1-8 of the embodiment of the present invention.It is real by comparison
A 1-8 and comparative example 1 are applied, although the tap density of the LiFePO4 of comparative example 1 is less than the nano-grade lithium iron phosphate of embodiment 1-8,
But the first discharge specific capacity of the LiFePO4 of comparative example 1 is less than the nano-grade lithium iron phosphate of embodiment 1-8, and comparative example 1
LiFePO4 assembling circulating battery fill charge and discharge 5 times after specific discharge capacity change greatly.It illustrates real using the present invention
The preparation method for applying the nano-grade lithium iron phosphate of example, the LiFePO4 conductivity finally obtained are preferable.
By comparative example 1-8 and comparative example 2-3, either particle diameter distribution, tap density is still discharged specific volume for the first time
Amount, the ferric phosphate of embodiment 1-8 are better than the ferric phosphate of comparative example 2-3.It is found by comparative example 1 and comparative example 2-3, it is real
Specific discharge capacity is little compared with first discharge specific capacity variation after applying battery cycle charge-discharge 5 times of the LiFePO4 assembling of example 1, and
The specific discharge capacity of comparative example 2-3 changes greatly.This is illustrated, in the preparation method of the nano-grade lithium iron phosphate of the embodiment of the present invention
In, using the preparation method of the nano-sheet ferric phosphate of the embodiment of the present invention, the LiFePO4 conductivity finally obtained is preferable.
In conclusion in LiFePO4 of the embodiment of the present invention and preparation method thereof, using ethylene glycol as organic solvent, by piece
Shape nano ferric phosphate, lithium source and carboxylic acid, surfactant dissolution in a solvent, first carry out wet ball grinding, by flake nano phosphoric acid
Iron, lithium source and carboxylic acid, surfactant are sufficiently mixed dissolution in organic solvent, and partial size becomes smaller, and are conducive to the progress of reaction.Piece
The item that the mixture that shape nano ferric phosphate, lithium source, organic solvent and carboxylic acid, surfactant are formed is 120-200 DEG C in temperature
After keeping the temperature 40-100min under part, it can be fully fused into fluid state, it can be mutual because of its flow regime between different substances
Infiltration.After then heating to 680-720 DEG C of heat preservation 10-13h, due to the complexing peptizaiton of the carboxylic acid in carboxylic acid sources, sheet is received
Rice ferric phosphate and lithium source occur complex reaction and generate nano-grade lithium iron phosphate.Lithium source is provided by lithium carbonate, lithium hydroxide or lithium oxalate,
Do not introduce other impurities.A kind of nano-grade lithium iron phosphate is prepared by the preparation method of above-mentioned nano-grade lithium iron phosphate.It has
Have the advantages that conductivity is preferable.
Embodiments described above is a part of the embodiment of the present invention, instead of all the embodiments.Reality of the invention
The detailed description for applying example is not intended to limit the range of claimed invention, but is merely representative of selected implementation of the invention
Example.Based on the embodiments of the present invention, obtained by those of ordinary skill in the art without making creative efforts
Every other embodiment, shall fall within the protection scope of the present invention.
Claims (8)
1. a kind of preparation method of nano-grade lithium iron phosphate, which is characterized in that including following preparation step:
Nano-sheet ferric phosphate, lithium source, organic solvent, carboxylic acid sources and surfactant are mixed and carry out wet ball grinding formation mixing
Object；Under the protection of inert gas, the mixture after heat preservation 40-100min, is risen under conditions of temperature is 120-200 DEG C
Temperature to 680-720 DEG C of heat preservation 10-13h, the lithium source includes lithium carbonate, lithium hydroxide or lithium oxalate, and the organic solvent includes
Ethylene glycol, the nano-sheet ferric phosphate, the lithium ion in the lithium source, the organic solvent, the carboxylic acid in the carboxylic acid sources
And the molar ratio of surfactant is 1:1-1.05:1-3:0.2-1:0.005-0.05；
The nano-sheet ferric phosphate is mainly prepared by the following steps to obtain: after source of iron, phosphorus source, complexing agent are mixed, slowly adding
Enter hydrogen peroxide and react 100-400min at a temperature of 70-100 DEG C, the pH value of the reaction system is 1.2-4, the hydrogen peroxide
Mass concentration is 20-30%, wherein ferro element, phosphate radical, the complexing agent and the hydrogen peroxide in the reaction system
Molar ratio is 1:1-1.6:0.01-0.05:0.5-2.0.
2. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the carboxylic acid sources include by grass
Acid and at least one of citric acid provide.
3. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the surfactant includes
At least one of cetyl trimethylammonium bromide, polysorbate and alkyl phenol polyoxyethylene ether.
4. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the ferro element, the phosphorus
The molar ratio of acid group, the complexing agent and the hydrogen peroxide is 1:1.1-1.5:0.02-0.04:0.8-1.5.
5. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the source of iron includes by acetic acid
At least one of iron, ferrous acetate, ferrous phosphate and biphosphate ferrous iron provide.
6. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that phosphorus source includes by phosphoric acid
At least one of ferrous, biphosphate ferrous iron and phosphoric acid provide.
7. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the complexing agent includes grass
At least one of acid, acetic acid and citric acid.
8. the preparation method of nano-grade lithium iron phosphate according to claim 1, which is characterized in that the pH value of the reaction system
It is to be adjusted by the way that phosphoric acid is added.
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| CN110357057B (en) * | 2019-07-22 | 2021-05-18 | 湖南雅城新材料有限公司 | Flaky iron phosphate and preparation method and application thereof |
| CN112938927B (en) * | 2021-05-12 | 2021-10-12 | 蜂巢能源科技有限公司 | Preparation method of lithium iron phosphate |
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