CN107170977A - A kind of preparation method of LiFePO4/graphene composite material, lithium ion cell positive, lithium ion battery - Google Patents
A kind of preparation method of LiFePO4/graphene composite material, lithium ion cell positive, lithium ion battery Download PDFInfo
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- CN107170977A CN107170977A CN201710424934.1A CN201710424934A CN107170977A CN 107170977 A CN107170977 A CN 107170977A CN 201710424934 A CN201710424934 A CN 201710424934A CN 107170977 A CN107170977 A CN 107170977A
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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
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—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
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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Abstract
The present invention relates to a kind of preparation method of LiFePO4/graphene composite material, lithium ion cell positive, lithium ion battery; preparation method step includes soaking three-dimensional redox graphene in the soak of ferric source, phosphoric acid root, lithium source and reducing agent, predecomposition, roasting under inert gas shielding after freeze-drying.LiFePO4/graphene composite material prepared by the present invention be applied to lithium ion battery, with high power capacity, have extended cycle life, low cost and easily large-scale production etc. excellent properties.
Description
Technical field
The present invention relates to technical field of nano material, and in particular to a kind of preparation of LiFePO4/graphene composite material
Method, lithium ion cell positive, lithium ion battery.
Background technology
New energy, such as wind energy, solar energy and geothermal energy, due to cleaning, it is efficient, renewable the advantages of and closed extensively
Note.However, above-mentioned scattered, discrete energy is difficult to be used directly, it usually needs energy-storage system is stored.Electrochmical power source
For one of most common energy storage system of today's society.Wherein, lithium ion battery (LIBs) because specific energy is high, have extended cycle life,
Memory-less effect and advantages of environment protection, the Main Trends of The Development as electrochmical power source have been widely used for various portable
The fields such as formula electronic equipment, electric automobile and space flight and aviation.Positive electrode as power lithium-ion battery nucleus, its
Cost and the performance cost and performance overall by battery is directly influenced.Transition metal phosphate has the open space of storage lithium,
It is the electric positive electrode of new lithium.Such as LiFePO4, with height ratio capacity 170mAh/g, low cost, the advantage of hypotoxicity.But
Its electrical conductivity is low by (10-9S/cm2), lithium ion diffusion poor (10-14~10-16cm2/ s), capacity attenuation when causing high power charging-discharging
Quickly.Research shows：The special construction and its excellent electron transport ability of graphene two dimension high-specific surface area, can effectively change
The electric conductivity of kind positive electrode, improves the diffusion transport ability of lithium ion.Therefore, exploitation excellent performance, cheap height
Stability composite positive electrode is the emphasis of Study on Li-ion batteries.
Graphene is as advanced carbon material, due to its superior electron conduction, big specific surface area and special
Two-dimensional structure and be considered as combination electrode material ideal composition.Three-dimensional grapheme is formed by the monoatomic layer stacking of carbon,
Have the advantages that extremely-low density, high surface area, high heat conduction, high temperature resistant, corrosion-resistant, ductility and pliability are good.Recently as
Further investigation to graphene finds that the satisfactory electrical conductivity of graphene has important work to the performance for improving lithium ion battery
With.Three-dimensional grapheme improves the electric conductivity and dispersiveness of composite, and electrolyte can be contacted fully with electrode material activity material,
So as to further increase the chemical property of three-dimensional graphene composite material.
LiFePO4Exist in nature in the form of triphylite, belong to rhombic system, space group is Pmnb.Each
There are 4 LiFePO4 units in structure cell, its cell parameter is:A=0.6008nm, b=1.0324nm, c=0.4694nm.Phosphoric acid
There is iron lithium stable, orderly olivine-type structure to be：Oxygen atom is tightly packed with six sides slightly distorted in crystal structure
Mode is arranged, and wherein Fe and Li is located at the octahedra center of oxygen atom respectively, forms FeO6Octahedra and LiO6It is octahedra.P is in oxygen
Atom tetrahedral center, forms PO4Tetrahedron, forms constitutionally stable three bit spaces network structure and passes through covalent bond
Connection, thus, LiFePO4 has good heat endurance and security as positive electrode, be particularly suitable on a large scale should
With.But high rate performance difference limits its practical application, this is by the slow lithium ion diffusion coefficient of its own and low electronics
What electrical conductivity was determined.At present, asked mostly using methods such as surface conductive layer cladding, ion doping and optimization patterns to solve this
Topic.Recent study work shows that the electricity of material can effectively be lifted by being combined lithium ion battery electrode material and graphene
Subconductivity, improves the high rate performance of material.Therefore LiFePO4/graphene three-dimensional structure composite is built, graphite is utilized
The electric conductivity of the flexible reticulated conductive structural improvement electrode material of alkene, can improve the high rate performance of material.Chinese invention is special
Sharp (publication number CN105514366A) " a kind of nitrogen-doped graphene is combined LiFePO4The preparation side of anode material for lithium-ion batteries
Method " discloses a kind of nitrogen-doped graphene and is combined LiFePO4The synthetic method of material is, it is necessary to by freeze-drying and two step high temperature
Processing, power consumption is big, and LiFePO4Distribution uniformity is poor on graphene, it is difficult to extensive synthesis.For example, in Tian
Xiaohui etc. (Journal of Power Sources, 2017,340,40-50) is prepared using hydro-thermal method and subsequent calcination
LiFePO4With graphene aerogel composite, LiFePO4On graphene aerogel surface and body phase skewness, so that shadow
Ring the performance of its lithium ion battery.In summary, graphene composite material is the mixing of graphene and LiFePO4 mostly at present
State, LiFePO4 is in graphenic surface and internal skewness, and in charge and discharge process, LiFePO4 is easily in graphene
On come off so that conductive capability declines, the performance of final influence lithium ion battery.
The content of the invention
In view of the deficiency that prior art is present, the technical problems to be solved by the invention are to provide a kind of LiFePO4/stone
The preparation method of black alkene composite, lithium ion cell positive, lithium ion battery.The present invention is prepared into using cheap raw material
To three-dimensional redox graphene, by hydro-thermal, compound, calcining, LiFePO4/graphene composite material is obtained.Pin of the present invention
To improving LiFePO4 as the extensive use of anode material for lithium-ion batteries and graphene composite material, there is provided a kind of technique
Simply, yield is high, easy expanding production preparation method.
A kind of preparation method of LiFePO4/graphene composite material, step includes：
A, by source of iron, phosphoric acid root, lithium source and reducing agent dissolving in deionized water, stir, obtain soak, so
Three-dimensional redox graphene is dispersed in soak afterwards mixed liquor placement is made；
One or more of the source of iron in frerrous chloride, ferrous sulfate, ferrous acetate, ferrous oxalate, iron in the rapid A
Concentration of the iron ion in mixed liquor is 0.05~0.80mol/L in source, the preferred frerrous chloride of source of iron, and iron ion is mixed in source of iron
The concentration closed in liquid is preferably 0.15~0.40mol/L；
One or more of the phosphoric acid root in phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid in the step A
Concentration of the root in mixed liquor is 0.05~0.80mol/L, and phosphoric acid root preferably phosphoric acid, concentration of the phosphate radical in mixed liquor is excellent
Elect 0.15~0.40mol/L as；
Lithium in one or more of the lithium source in lithium chloride, lithium sulfate, lithium nitrate, lithium acetate, lithium source in the step A
Concentration of the ion in mixed liquor is 0.05~0.80mol/L, the preferred lithium chloride of lithium source, and concentration of the lithium in mixed liquor is preferably
0.15~0.40mol/L；
Iron ion, phosphate radical, the amount ratio of the material of lithium ion are 1 in the soak:1:1；
One or more of the reducing agent in ascorbic acid, hydrazine hydrate, hydroxylamine hydrochloride in the step A, reducing agent exists
Concentration in soak is 0.05~0.80mol/L, and the preferred ascorbic acid of reducing agent, concentration of the reducing agent in mixed liquor is preferred
For 0.15~0.40mol/L；
Concentration of the three-dimensional redox graphene in mixed liquor is 0.1~6.0g/L in the step A, preferably 0.6~
3.0g/L；
Standing time is more than 1 day, preferably 1-3 days in the rapid A；
The temperature of mixed liquor is 3~80 DEG C, preferably 10~30 DEG C when being placed in the rapid A；
B, distil the mixed liquor vacuum freeze drying after placement to moisture obtained solid mixture completely；
It is -50~0 DEG C that temperature is freeze-dried in the step B, and preferably freeze drying temperature is -50~-20 DEG C；Freezing is dry
The dry time is more than 2 days, and the preferably freeze drying time is 2~4 days；The vacuum of vacuum freeze drying<50Pa；
C, by solid mixture before predecomposition obtains reaction in 1~6 hour under 160~450 DEG C of inert gas shielding atmosphere
Drive body, preferably 160~300 DEG C predecomposition 1~4 hour；Then by precursors in 450~750 DEG C of inert gas shielding gas
Roasting obtains product in 24~36 hours under atmosphere, and in 450~600 DEG C of roastings precursors preferably were obtained into phosphoric acid in 24~30 hours
Iron lithium/graphene composite material.
Inert gas is selected from one or both of nitrogen and argon gas, preferably high pure nitrogen in the step C；
The preparation method of three-dimensional redox graphene is in the step A：
Graphite oxide is dispersed in water the outstanding mixed liquid of obtained graphite oxide, the concentrated sulfuric acid, and ultrasound point are added into outstanding mixed liquid
Uniformly obtained mixed liquor is dissipated, then mixed liquor is put into reactor at 160~260 DEG C and reacts 18~24 hours, preferably 190
Reacted 20~24 hours at~220 DEG C, washing obtains three-dimensional redox graphene；
The step graphene oxide is synthesized by improving Hummers methods, is concretely comprised the following steps：
5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring is slowly added to
The 150mL concentrated sulfuric acid, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue after stirring 20 hours,
Due to reactant viscosity increase, stop stirring, obtain the purplish red color substance of starchiness.After placing 5 days, 500mL is respectively added slowly to
Deionized water and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation, washing,
Obtain graphite oxide；
The concentration of graphene oxide is 0.75~1.5g/L, preferably 1.0~1.25g/L in the step mixed liquor；
The concentration of sulfuric acid is 1.2~2.5mol/L, preferably 1.7~1.9mol/L in the step mixed liquor.
A kind of LiFePO4/graphene composite material, by the preparation method system of above-mentioned LiFePO4/graphene composite material
；
A kind of lithium ion cell positive, is made up of LiFePO4/graphene composite material.
A kind of lithium ion battery, is made up of the lithium ion cell positive being made including LiFePO4/graphene composite material.
The present invention be directed to LiFePO4 lithium ion diffusion coefficient slow in lithium ion battery applications and low electronics electricity
The deficiency such as conductance is studied, a kind of novel phosphoric acid iron lithium/graphene composite material of design synthesis.On the one hand, three-dimensional grapheme
Shorten lithium ion (Li+) diffusion length in crystal；On the other hand, three-dimensional grapheme effectively improves the electricity of material surface
Subconductivity, is conducive to the transmission of electronics in the composite, thus LiFePO4 with graphene is compound can increase its electricity
Chemical property.The present invention synthesizes three-dimensional redox graphene using hydro-thermal method, is immersed in source of iron, phosphoric acid root, lithium source
In the soak of reducing agent, LiFePO4 and graphene composite material are obtained by frozen drying and subsequent calcination, should
Materials application in lithium ion battery, with high power capacity, have extended cycle life, low cost and easy excellent properties such as large-scale production.
Main innovation point of the present invention is three-dimensional redox graphene as substrate, by frozen drying and subsequently
Calcining so that LiFePO4 uniform load is in three-dimensional redox graphene surface and pore passage structure.
The present invention has advantages below compared with prior art：
(1) LiFePO4 obtained by and graphene composite material, LiFePO4 are supported on three-dimensional grapheme surface and duct
In structure, three-dimensional cavernous structure promote composite fully contacted with lithium-ion electrolyte, three-dimensional grapheme serve reparation with
The effect of carbon-coating is bridged, further the chemical property of optimization LiFePO4；
(2) LiFePO4 obtained by is stable with graphene composite material performance, high temperature resistant, and graphene improves the conduction of material
Property, the abundant space of three-dimensional cavernous structure structure provides passage for the quick transmission of lithium ion, is conducive to lithium ion on surface
Reactivity site is transmitted and arrives at, so as to improve the electric conductivity of LiFePO4；
(3) specific surface area of LiFePO4 obtained by and graphene composite material is big, the multiple pleat on three-dimensional grapheme surface
Wrinkle has high specific surface area there is provided the substantial amounts of load site of LiFePO4, while also reduce lithium iron phosphate particles size,
Improve lithium ion diffusion rate；
(4) LiFePO4 obtained by is used for lithium ion battery with graphene composite material, and capacity is high, heat endurance is good, green
The advantage high power capacity such as colour circle guarantor, stable circulation and have extended cycle life；
(5) experimental procedure is simple, requires low to the instrument and equipment used in experiment, and extensively, cost is low, can carry out for raw material sources
Batch production.
Brief description of the drawings
Fig. 1 is the SEM figures of LiFePO4/graphene composite material prepared by embodiment 1；
Fig. 2 is the SEM figures of LiFePO4/graphene composite material prepared by embodiment 2；
Fig. 3 is the SEM figures of LiFePO4/graphene composite material prepared by embodiment 3；
Fig. 4 is the XRD of LiFePO4/graphene composite material prepared by embodiment 3；
Fig. 5 is the SEM figures of LiFePO4/graphene composite material prepared by embodiment 4；
Fig. 6 is the SEM figures of LiFePO4/graphene composite material prepared by embodiment 5；
Fig. 7 be embodiment 4 prepare LiFePO4/graphene composite material as anode material for lithium-ion batteries in electric current
Cyclical stability test chart under density 0.1C.
Embodiment
Embodiment 1
The preparation method of LiFePO4 and graphene composite material, comprises the following steps：
Hydro-thermal process：5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring, delays
The slow concentrated sulfuric acid for adding 150mL, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue stirring 20 small
Shi Hou, due to reactant viscosity increase, stops stirring, obtains the purplish red color substance of starchiness.After placing 5 days, it is respectively added slowly to
500mL deionized waters and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation,
Washing, obtains graphite oxide.70mg graphite oxides are dissolved in 80mL deionized waters, the 6mL concentrated sulfuric acids (ρ=1.84g/ is added
cm3), solution is moved into vial, is then averaged and is transferred in 5 hydrothermal reaction kettles by ultrasonic disperse 3 hours,
Reacted 20 hours in 200 DEG C of baking ovens, washing, collection obtains the three-dimensional redox graphenes of 14mg.
Compound working procedure：0.38g frerrous chlorides and 0.12g lithium chlorides are dissolved in 12mL deionized waters, 131.24 μ are added
L concentrated phosphoric acids (ρ=1.69g/cm3) and 109.78 μ L hydrazine hydrates (ρ=1.03g/cm3), after being completely dissolved, 14mg three-dimensionals are reduced
Graphene oxide is put into above-mentioned solution, is soaked 2 days, is then turned solution and three-dimensional redox graphene in 20 DEG C of water-baths
Move in plastic beaker, be freeze-dried 4 days at -50 DEG C, solid mixture predecomposition under 160 DEG C of high pure nitrogen atmosphere will be obtained
Obtain precursors within 3 hours, then above-mentioned precursors are calcined 30 hours under 500 DEG C of high pure nitrogen atmosphere again, obtained
To LiFePO4/graphene composite material.
Embodiment 2
The preparation method of LiFePO4 and graphene composite material, comprises the following steps：
Hydro-thermal process：5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring, delays
The slow concentrated sulfuric acid for adding 150mL, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue stirring 20 small
Shi Hou, due to reactant viscosity increase, stops stirring, obtains the purplish red color substance of starchiness.After placing 5 days, it is respectively added slowly to
500mL deionized waters and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation,
Washing, obtains graphite oxide.100mg graphite oxides are dissolved in 80mL deionized waters, the 8mL concentrated sulfuric acids are added, ultrasonic disperse 3 is small
When, solution is moved into vial, then then it be averaged and is transferred in 5 hydrothermal reaction kettles, in 180 DEG C of baking ovens
Middle reaction 24 hours, washing, collection obtains the three-dimensional redox graphenes of 20mg.
Compound working procedure：0.42g ferrous acetates, 0.31g diammonium hydrogen phosphates and 0.15g lithium sulfates are dissolved in 12mL deionizations
In water, 137.22 μ L hydrazine hydrates (ρ=1.03g/cm are added3), after being completely dissolved, the three-dimensional redox graphenes of 20mg are put into
In above-mentioned solution, soaked in 10 DEG C of water-baths 3 days, solution and three-dimensional redox graphene are then transferred to plastic beaker
In, it is freeze-dried 3 days at -40 DEG C, solid mixture predecomposition under 200 DEG C of high pure nitrogen atmosphere will be obtained and obtained within 2 hours instead
Answer presoma, be then again calcined above-mentioned precursors 24 hours under 650 DEG C of high pure nitrogen atmosphere, obtain LiFePO4/
Graphene composite material.
Embodiment 3
The preparation method of LiFePO4 and graphene composite material, comprises the following steps：
Hydro-thermal process：5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring, delays
The slow concentrated sulfuric acid for adding 150mL, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue stirring 20 small
Shi Hou, due to reactant viscosity increase, stops stirring, obtains the purplish red color substance of starchiness.After placing 5 days, it is respectively added slowly to
500mL deionized waters and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation,
Washing, obtains graphite oxide.120mg graphite oxides are dissolved in 80mL deionized waters, the 10mL concentrated sulfuric acids, ultrasonic disperse 3 is added
Hour, solution is moved into vial, is then averaged and is transferred in 5 hydrothermal reaction kettles, is reacted in 200 DEG C of baking ovens
18 hours, washing, collection obtained the three-dimensional redox graphenes of 24mg.
Compound working procedure：0.83g ferrous sulfate, 0.35g ammonium dihydrogen phosphates, 0.21g lithium nitrates and 0.21g hydroxylamine hydrochlorides is molten
Solution is in 12mL deionized waters, after being completely dissolved, and the three-dimensional redox graphenes of 24mg is put into above-mentioned solution, in 20 DEG C of water
Soaked in bath 2 days, then solution and three-dimensional redox graphene are transferred in plastic beaker, 3 are freeze-dried at -30 DEG C
My god, solid mixture predecomposition under 250 DEG C of high-purity argon gas atmosphere will be obtained and obtain precursors within 1.5 hours, then again will
Above-mentioned precursors are calcined 24 hours under 600 DEG C of high-purity argon gas atmosphere, obtain LiFePO4/graphene composite material.
Embodiment 4
The preparation method of LiFePO4 and graphene composite material, comprises the following steps：
Hydro-thermal process：5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring, delays
The slow concentrated sulfuric acid for adding 150mL, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue stirring 20 small
Shi Hou, due to reactant viscosity increase, stops stirring, obtains the purplish red color substance of starchiness.After placing 5 days, it is respectively added slowly to
500mL deionized waters and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation,
Washing, obtains graphite oxide.60mg graphite oxides are dissolved in 80mL deionized waters, the 12mL concentrated sulfuric acids are added, ultrasonic disperse 3 is small
When, solution is moved into vial, is then averaged and is transferred in 5 hydrothermal reaction kettles, 24 are reacted in 200 DEG C of baking ovens
Hour, washing, collection obtains the three-dimensional redox graphenes of 12mg.
Compound working procedure：By 0.72g frerrous chlorides, 0.37g lithium acetates and 0.64g dissolution of ascorbic acid in 12mL deionized waters
In, add 246.07 μ L concentrated phosphoric acids (ρ=1.69g/cm3), after being completely dissolved, the three-dimensional redox graphenes of 12mg are put into
State in solution, soak 2 days, solution and three-dimensional redox graphene are transferred in plastic beaker in 25 DEG C of water-baths then,
It is freeze-dried 2 days at -20 DEG C, before obtaining solid mixture predecomposition obtaining reaction in 1 hour under 300 DEG C of high-purity argon gas atmosphere
Body is driven, then above-mentioned precursors are calcined 24 hours under 550 DEG C of high-purity argon gas atmosphere again, LiFePO4/graphite is obtained
Alkene composite.
Embodiment 5
The preparation method of LiFePO4 and graphene composite material, comprises the following steps：
Hydro-thermal process：5.0g graphite and 3.75g NaNO are weighed respectively3It is put into 1L beaker, mechanical strong stirring, delays
The slow concentrated sulfuric acid for adding 150mL, stirs 0.5 hour, is slow added into 20g KMnO4, add within 0.5 hour, continue stirring 20 small
Shi Hou, due to reactant viscosity increase, stops stirring, obtains the purplish red color substance of starchiness.After placing 5 days, it is respectively added slowly to
500mL deionized waters and 30mL H2O2, now solution colour be changed into obvious glassy yellow, after solution fully reacts, centrifugation,
Washing, obtains graphite oxide.90mg graphite oxides are dissolved in 80mL deionized waters, the 12mL concentrated sulfuric acids are added, ultrasonic disperse 3 is small
When, solution is moved into vial, is then averaged and is transferred in 5 hydrothermal reaction kettles, 18 are reacted in 200 DEG C of baking ovens
Hour, washing, collection obtains the three-dimensional redox graphenes of 18mg.
Compound working procedure：By 1.20g ferrous sulfate, 0.26g lithium chlorides and 0.76g dissolution of ascorbic acid in 12mL deionized waters
In, add 295.28 μ L concentrated phosphoric acids (ρ=1.69g/cm3), after being completely dissolved, the three-dimensional redox graphenes of 18mg are put into
State in solution, soak 2 days, solution and three-dimensional redox graphene are transferred in plastic beaker in 10 DEG C of water-baths then,
It is freeze-dried 2 days at -20 DEG C, before obtaining solid mixture predecomposition obtaining reaction in 1 hour under 300 DEG C of high pure nitrogen atmosphere
Body is driven, then above-mentioned precursors are calcined 24 hours under 550 DEG C of nitrogen atmospheres again, LiFePO4/graphene are obtained multiple
Condensation material.
Using the gained final product LiFePO4 of embodiment 4 and graphene composite material as lithium ion battery positive pole material
Material, uses the mass ratio of LiFePO4 and graphene composite material, acetylene black and PVDF for 85:5:10, with N- crassitudes
Ketone (NMP) solvent is modulated into uniform pulpous state；Slurry is applied on aluminium foil, with scraper by its even spread patches,
Copper foil surface is attached to evenly.The coating being made is put in baking oven, is dried 12 hours with 110 DEG C；Vacuum is moved into after the completion of drying
In drying box, it is dried in vacuo 10 hours with 120 DEG C；Dried composite coating is carried out at tabletting using tablet press machine again
Reason；Electrode slice is cut using mechanical slitter, using lithium piece as to electrode, electrolyte is commercially available 1molL-1LiPF6/EC+DMC
Solution, charge-discharge performance test is carried out using cell tester, and products therefrom LiFePO4 is used as lithium with graphene composite material
Cyclical stability test result of the ion battery positive electrode under current density 0.1C is as shown in Figure 7.From accompanying drawing 7,
The good cycling stability of battery, battery capacity is still stablized in 141.6mAhg after circulating 50 times-1。
Claims (10)
1. a kind of preparation method of LiFePO4/graphene composite material, step includes：
A, by source of iron, phosphoric acid root, lithium source and reducing agent dissolving in deionized water, stir, obtain soak, then will
Three-dimensional redox graphene, which is dispersed in soak, is made mixed liquor placement；
B, distil the mixed liquor vacuum freeze drying after placement to moisture obtained solid mixture completely；
C, by solid mixture, predecomposition obtains precursors in 1~6 hour under 160~450 DEG C of inert gas shielding atmosphere,
It is preferred that 160~300 DEG C of predecomposition 1~4 hour；Then precursors are roasted under 450~750 DEG C of inert gas shielding atmosphere
Burning obtain product within 24~36 hours, preferably by precursors 450~600 DEG C roasting obtain within 24~30 hours LiFePO4/
Graphene composite material.
2. preparation method as claimed in claim 1, it is characterised in that：
In the rapid A in one or more of the source of iron in frerrous chloride, ferrous sulfate, ferrous acetate, ferrous oxalate, source of iron
Concentration of the iron ion in mixed liquor is 0.05~0.80mol/L, the preferred frerrous chloride of source of iron, and iron ion is in mixed liquor in source of iron
In concentration be preferably 0.15~0.40mol/L；
One or more of the phosphoric acid root in phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate in the step A, phosphate radical exists
Concentration in mixed liquor is 0.05~0.80mol/L, phosphoric acid root preferably phosphoric acid, and concentration of the phosphate radical in mixed liquor is preferably
0.15~0.40mol/L；
Lithium ion in one or more of the lithium source in lithium chloride, lithium sulfate, lithium nitrate, lithium acetate, lithium source in the step A
Concentration in mixed liquor is 0.05~0.80mol/L, the preferred lithium chloride of lithium source, and concentration of the lithium in mixed liquor is preferably 0.15
~0.40mol/L.
3. preparation method as claimed in claim 1, it is characterised in that：Iron ion in the soak, phosphate radical, lithium ion
The amount ratio of material is 1:1:1.
4. preparation method as claimed in claim 1, it is characterised in that：Reducing agent is selected from ascorbic acid, hydration in the step A
One or more in hydrazine, hydroxylamine hydrochloride, concentration of the reducing agent in soak is 0.05~0.80mol/L, and reducing agent is preferred
Ascorbic acid, concentration of the reducing agent in mixed liquor is preferably 0.15~0.40mol/L.
5. preparation method as claimed in claim 1, it is characterised in that：Three-dimensional redox graphene is mixed in the step A
It is 0.1~6.0g/L, preferably 0.6~3.0g/L to close the concentration in liquid.
6. preparation method as claimed in claim 1, it is characterised in that：Standing time is more than 1 day, preferably 1-3 in the rapid A
My god；The temperature of mixed liquor is 3~80 DEG C, preferably 10~30 DEG C when being placed in the rapid A.
7. preparation method as claimed in claim 1, it is characterised in that：It is -50~0 DEG C that temperature is freeze-dried in the step B,
Preferably freeze drying temperature is -50~-20 DEG C；Sublimation drying is more than 2 days, and the preferably freeze drying time is 2~4 days；
The vacuum of vacuum freeze drying<50Pa.
8. preparation method as claimed in claim 1, it is characterised in that：Inert gas is selected from nitrogen and argon gas in the step C
One or both of, preferred high pure nitrogen.
9. a kind of LiFePO4/graphene composite material, is made by the preparation method of LiFePO4/graphene composite material.
10. a kind of lithium ion cell positive, is made up of LiFePO4/graphene composite material.
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| CN109216673A (en) * | 2018-08-19 | 2019-01-15 | 杭州电子科技大学 | LiFePO4/multi-layer graphene composite material and preparation method and the lithium ion battery for applying it |
| CN109935828A (en) * | 2017-12-15 | 2019-06-25 | 福建省致格新能源电池科技有限公司 | A kind of nano-grade lithium iron phosphate composite material |
| CN114784249A (en) * | 2022-04-29 | 2022-07-22 | 楚能新能源股份有限公司 | Lithium iron phosphate composite positive electrode material and preparation method thereof |
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