CN107845792A - A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode - Google Patents

A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode Download PDF

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CN107845792A
CN107845792A CN201710982877.9A CN201710982877A CN107845792A CN 107845792 A CN107845792 A CN 107845792A CN 201710982877 A CN201710982877 A CN 201710982877A CN 107845792 A CN107845792 A CN 107845792A
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lifepo4
graphene
positive electrode
ion battery
lithium ion
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许东伟
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Shenzhen City Yu Feng New Material Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/362Composites
    • H01M4/366Composites as layered products
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/58Selection 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
    • H01M4/5825Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/58Selection 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
    • H01M4/583Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

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Abstract

The invention belongs to technical field of lithium batteries, a kind of more particularly to LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode, the positive electrode has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and formed with pore structure on the graphene, the aperture of the pore structure is 5nm 100nm, and the specific surface area of the positive electrode is 30 300 ㎡/g.Relative to prior art, positive electrode provided by the invention has core shell structure, wherein, the material of nuclear structure is LiFePO4, the material of shell structure is graphene, and formed with pore structure on graphene, because the addition of graphene improves the electric conductivity of LiFePO 4 material, because ferric ion is reduced to ferrous iron in preparation process, part carbon in graphene sheet layer is consumed as reducing agent, then the hole that lithium ion passes through is available in Surface Creation, improves the high rate performance and fast charging and discharging ability of LiFePO 4 material.

Description

A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode
Technical field
The invention belongs to technical field of lithium batteries, more particularly to a kind of LiFePO4/graphene with loose structure are multiple Close anode material of lithium battery.
Background technology
As development of the whole world to new-energy automobile is increasingly paid attention to, the power as one of new-energy automobile core component Battery turns into research emphasis.Either hybrid power or pure electric vehicle, lithium ion battery is due to its higher energy The advantages that density, longer service life, safe and pollution-free and less self discharge coefficient, becomes current combination property most Good battery.
Positive electrode is one of the key factor for restricting lithium battery performance, LiFePO4 aboundresources, cheap, safety Performance is good and environmentally friendly, is the positive electrode of the lithium-ion-power cell of current domestic main flow, especially because its safety Excellent performance is widely applied in pure Electric Transit field.On the other hand, LiFePO4 is again poor with high rate performance, energy The features such as density is low, it is impossible to meet the use demand of new-energy automobile heavy-current discharge, this in turn limits it on electrokinetic cell Application.Graphene has the advantages that very high specific surface area and excellent electric conductivity, in lithium ion battery and super capacitor The fields such as device are using quite varied.
The chemical property of improvement LiFePO4 is adulterated or is coated with the prior art using graphene and LiFePO4 It is poor high rate performance to be present in method, and chemical property improves unconspicuous problem.
In view of this, the present invention is intended to provide a kind of LiFePO4 with loose structure/graphene composite lithium ion battery just Pole material, it has the core shell structure that graphene-coated lithium iron phosphate is formed, and has loose structure on graphene, so as to carry The high high rate performance and fast charging and discharging ability of LiFePO 4 material.
The content of the invention
It is an object of the invention to:In view of the shortcomings of the prior art, provide a kind of LiFePO4 with loose structure/ Graphene composite lithium ion battery positive electrode, it has the core shell structure that graphene-coated lithium iron phosphate is formed, and on graphene With loose structure, so as to improve the high rate performance of LiFePO 4 material and fast charging and discharging ability.
In order to achieve the above object, the present invention adopts the following technical scheme that:
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode, the positive electrode have Core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and shape on the graphene Into there is pore structure, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 30-300 ㎡/g.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, The particle diameter of the LiFePO4 is 1 μm -5 μm, and the thickness of the graphene is 10nm-100nm.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, The preparation method of the positive electrode comprises at least following steps:
The first step, deionized water is mixed with lithium salts, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B;
3rd step, disperses 1h~2h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphite is made Alkene presoma;Spray drying easily forms the big particle of tiny specific surface area, and efficiency high, speed are fast
4th step, LiFePO4/graphene presoma is placed in inert gas, with 1 DEG C/min~10 DEG C/min liter Warm speed, it is warming up to 600 DEG C~800 DEG C and is incubated 6h~12h, is cooled to room temperature and the ferric phosphate with loose structure is made Lithium/graphene composite lithium ion battery positive electrode.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, Lithium salts described in the first step is at least one of lithium carbonate, lithium acetate, lithium citrate and lithium nitrate.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, In the first step, the mol ratio of the lithium in the lithium salts and the iron in the ferric phosphate is (0.98~1.02):1.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, In the first step, in mixture A, the concentration of lithium salts is 0.01mol/L~2mol/L.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, In the first step, in mass, the content of the sucrose is the 0.5%~1% of theoretical LiFePO4 yield.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, In second step, in mass, the content of graphene is the 0.1%~2% of theoretical LiFePO4 yield.
There is a kind of of LiFePO4/graphene composite lithium ion battery positive electrode of loose structure to improve as the present invention, Inert gas described in 4th step is argon gas and/or nitrogen.
Relative to prior art, positive electrode provided by the invention has core shell structure, wherein, the material of nuclear structure is phosphorus Sour iron lithium, the material of shell structure is graphene, and formed with pore structure on graphene, because the addition of graphene improves phosphorus The electric conductivity of sour iron lithium material, because ferric ion is reduced to ferrous iron in preparation process, the part in graphene sheet layer Carbon is consumed as reducing agent, is then available for the hole that lithium ion passes through in Surface Creation, this structure can utilize graphite The superior electrical conductivity energy and high electron mobility of alkene material, while ensure contact of the LiFePO4 with electrolyte, there is provided lithium ion The path passed through, improve the high rate performance and fast charging and discharging ability of LiFePO 4 material.Meanwhile preparation technology letter of the present invention Single controllable, raw material selectable range is extensive, is easy to industrialized production.
Brief description of the drawings
A and B in Fig. 1 are the ESEM shape appearance figure (SEM figures) of the gained positive electrode of embodiment 1 in the present invention.
Fig. 2 is that the high rate performance of the gained positive electrode of embodiment 1 in the present invention tests collection of illustrative plates.
Fig. 3 is embodiment 1 in the present invention, embodiment 3, embodiment 6, the X-ray diffraction of positive electrode made from embodiment 7 Collection of illustrative plates.
Embodiment
Embodiment 1
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 180 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, deionized water is mixed with lithium carbonate, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;Wherein, The mol ratio of the iron in lithium and ferric phosphate in lithium carbonate is 1:1, in mixture A, the concentration of lithium carbonate is 0.5mol/L, with Quality meter, the content of sucrose are the 0.6% of theoretical LiFePO4 yield.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B, in mass, the content of graphene is theoretical LiFePO4 yield 0.5%.
3rd step, disperses 1.5h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in nitrogen, with 5 DEG C/min heating rate, is warming up to 700 DEG C and 10h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
The SEM of the positive electrode is schemed as shown in figure 1, as seen from Figure 1, the particle diameter of the material is about 1 μm -5 μm.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, Acquired results are shown in Fig. 2, and as seen from Figure 2, capacity is 162mAh/g after the half-cell circulates 100 times under 0.1C, under 5C Capacity is the 74% of 0.1C after circulating 100 times.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
The XRD of the positive electrode is shown in Fig. 3, and as seen from Figure 3, its crystallinity is good.
Embodiment 2
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 130 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, deionized water is mixed with lithium acetate, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;Wherein, The mol ratio of the iron in lithium and ferric phosphate in lithium acetate is 1.01:1, in mixture A, the concentration of lithium acetate is 1mol/L, In mass, the content of sucrose is the 0.8% of theoretical LiFePO4 yield.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B;In mass, the content of graphene is theoretical LiFePO4 yield 1%.
3rd step, disperses 1.2h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in argon gas, with 3 DEG C/min heating rate, is warming up to 650 DEG C and 9h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 160mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 75% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
Embodiment 3
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 100 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, deionized water is mixed with lithium citrate, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;Its In, the mol ratio of the iron in lithium and ferric phosphate in lithium citrate is 0.99:1, in mixture A, the concentration of lithium citrate is 1.5mol/L, in mass, the content of sucrose are the 0.9% of theoretical LiFePO4 yield.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B, the content of graphene is the 1.4% of theoretical LiFePO4 yield;
3rd step, disperses 1.8h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in nitrogen, with 8 DEG C/min heating rate, is warming up to 750 DEG C and 8h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Its XRD is shown in Fig. 3, and as seen from Figure 3, its crystallinity is good.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 156mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 78% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
Embodiment 4
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 230 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, deionized water is mixed with lithium nitrate, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;Wherein, The mol ratio of the iron in lithium and ferric phosphate in lithium nitrate is 0.98:1, in mixture A, the concentration of lithium nitrate is 1.2mol/ L, in mass, the content of sucrose are the 0.65% of theoretical LiFePO4 yield.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B;The content of graphene is the 1.8% of theoretical LiFePO4 yield.
3rd step, disperses 1.6h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in argon gas, with 6 DEG C/min heating rate, is warming up to 720 DEG C and 7h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 165mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 70% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
Embodiment 5
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 150 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, by deionized water, (mixture of lithium carbonate and lithium acetate, the mass ratio of the two are 1 with lithium salts:1), phosphorus Sour iron, sucrose mix and are sufficiently stirred to obtain mixture A;Wherein, the mol ratio of the iron in the lithium and ferric phosphate in lithium salts is 0.995:1, in mixture A, the concentration of lithium salts is 0.3mol/L, and in mass, the content of sucrose is produced for theoretical LiFePO4 The 0.85% of amount.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B;The content of graphene is the 0.7% of theoretical LiFePO4 yield.
3rd step, disperses 1.9h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in argon gas, with 2 DEG C/min heating rate, is warming up to 780 DEG C and 8.5h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 162mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 77% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
Embodiment 6
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 70 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, by deionized water, (mixture of lithium acetate and lithium citrate, the mass ratio of the two are 1 with lithium salts:2)、 Ferric phosphate, sucrose mix and are sufficiently stirred to obtain mixture A;Wherein, the mol ratio of the iron in the lithium and ferric phosphate in lithium salts is 0.105:1, in mixture A, the concentration of lithium salts is 0.6mol/L, and in mass, the content of sucrose is produced for theoretical LiFePO4 The 0.75% of amount.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B;
3rd step, disperses 1h~2h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphite is made Alkene presoma;The content of graphene is the 0.85% of theoretical LiFePO4 yield.
4th step, LiFePO4/graphene presoma is placed in nitrogen, with 4 DEG C/min heating rate, is warming up to 620 DEG C and 6h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Its XRD is shown in Fig. 3, and its crystallinity is good as shown in Figure 3.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 150mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 74% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
Embodiment 7
A kind of LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode is present embodiments provided, just Pole material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and graphite Formed with pore structure on alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 260 ㎡/g.
Wherein, the particle diameter of LiFePO4 is 1 μm -5 μm, and the thickness of graphene is 10nm-100nm.
The preparation method of the positive electrode comprises at least following steps:
The first step, by deionized water, (mixture of lithium citrate and lithium nitrate, the mass ratio of the two are 1 with lithium salts:3)、 Ferric phosphate, sucrose mix and are sufficiently stirred to obtain mixture A;Wherein, the mol ratio of the iron in the lithium and ferric phosphate in lithium salts is 0.108:1, in mixture A, the concentration of lithium salts is 0.8mol/L, and in mass, the content of sucrose is produced for theoretical LiFePO4 The 0.95% of amount.
Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into stone In black alkene dispersion liquid, it is sufficiently stirred to obtain mixture B, the content of graphene is the 0.9% of theoretical LiFePO4 yield;
3rd step, disperses 1.8h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene is made Presoma;
4th step, LiFePO4/graphene presoma is placed in argon gas, with 7 DEG C/min heating rate, is warming up to 690 DEG C and 12h is incubated, is cooled to room temperature and LiFePO4/graphene composite lithium ion battery positive pole material with loose structure is made Material.
Its XRD is shown in Fig. 3, and as seen from Figure 3, its crystallinity is good.
Using the positive electrode as active material, using lithium metal as to electrode, assemble half-cell, test its cycle performance, As a result show, capacity is 170mAh/g after the half-cell circulates 100 times under 0.1C, and capacity is after being circulated 100 times under 5C The 71% of 0.1C.Its high rate performance and fast charging and discharging ability are preferable as can be seen here.
The announcement and teaching of book according to the above description, those skilled in the art in the invention can also be to above-mentioned embodiment party Formula is changed and changed.Therefore, the invention is not limited in embodiment disclosed and described above, to the present invention's Some modifications and changes should also be as falling into the scope of the claims of the present invention.In addition, although used in this specification Some specific terms, but these terms are merely for convenience of description, do not form any restrictions to the present invention.

Claims (9)

  1. A kind of 1. LiFePO4 with loose structure/graphene composite lithium ion battery positive electrode, it is characterised in that:The positive pole Material has core shell structure, wherein, the material of nuclear structure is LiFePO4, and the material of shell structure is graphene, and the stone Formed with pore structure on black alkene, the aperture of the pore structure is 5nm-100nm, and the specific surface area of the positive electrode is 30-300 ㎡/g。
  2. 2. the LiFePO4 according to claim 1 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is:The particle diameter of the LiFePO4 is 1 μm -5 μm, and the thickness of the graphene is 10nm-100nm.
  3. 3. the LiFePO4 according to claim 1 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is that the preparation method of the positive electrode comprises at least following steps:
    The first step, deionized water is mixed with lithium salts, ferric phosphate, sucrose and is sufficiently stirred to obtain mixture A;
    Second step, deionized water and graphene are mixed to prepare graphene dispersing solution, then mixture A is slowly added into graphene In dispersion liquid, it is sufficiently stirred to obtain mixture B;
    3rd step, disperses 1h ~ 2h by mixture B under ultrasound condition, is then spray-dried and LiFePO4/graphene forerunner is made Body;
    4th step, LiFePO4/graphene presoma is placed in inert gas, with 1 DEG C/min ~ 10 DEG C/min heating speed Rate, it is warming up to 600 DEG C ~ 800 DEG C and is incubated 6h ~ 12h, is cooled to room temperature and LiFePO4/graphite with loose structure is made Alkene composite lithium ion battery positive electrode.
  4. 4. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is that lithium salts described in the first step is at least one of lithium carbonate, lithium acetate, lithium citrate and lithium nitrate.
  5. 5. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is, in the first step, the mol ratio of the lithium in the lithium salts and the iron in the ferric phosphate is(0.98~1.02):1.
  6. 6. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is, in the first step, in mixture A, the concentration of lithium salts is 0.01 mol/L ~ 2mol/L.
  7. 7. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is, in the first step, in mass, the content of the sucrose is the 0.5% ~ 1% of theoretical LiFePO4 yield.
  8. 8. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is, in second step, in mass, the content of graphene is the 0.1% ~ 2% of theoretical LiFePO4 yield.
  9. 9. the LiFePO4 according to claim 3 with loose structure/graphene composite lithium ion battery positive electrode, it is special Sign is that inert gas described in the 4th step is argon gas and/or nitrogen.
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