CN108598474B - A kind of high-energy density lithium battery lithium iron phosphate positive material and preparation method thereof - Google Patents
A kind of high-energy density lithium battery lithium iron phosphate positive material and preparation method thereof Download PDFInfo
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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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Abstract
The present invention relates to a kind of high-energy density lithium battery lithium iron phosphate positive material and preparation method thereof, the preparation method is the following steps are included: (1) polyacrylonitrile containing lithium salts spinning solution is prepared；(2) spinning solution of polyacrylonitrile containing ferrous salt is prepared；(3) the electrostatic spinning preparation of nano fiber non-woven fabric: lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into two spinning syringes and is placed in spinning equipment, electrostatic spinning obtains nano fiber non-woven fabric；(4) the LiFePO4 carbon nano-composite material that is carbonized to obtain of nano fiber non-woven fabric；(5) it post-processes: LiFePO4 carbon nano-composite material is added in manganese salt solution, after dispersion, carry out a series of subsequent drying and processings, to obtain the final product.It has the beneficial effect that, prepares lithium salts and ferrous salt solution respectively, then interlocked again by electrostatic spinning uniformly compound, it is ensured that properties of product stable homogeneous, while being conducive to raw materials recovery；Manganese salt post-processing is conducive to energy density promotion.
Description
Technical field
The present invention relates to anode material for lithium-ion batteries, relate in particular to a kind of high-energy density lithium battery LiFePO4
Positive electrode and preparation method thereof belongs to power battery technology field.
Background technique
21 century facing mankind energy crisis and environmental pollution two serious problems, therefore clean renewable new energy
Exploitation has far reaching significance with research.Wherein, all kinds of automobiles account for 40% or so of consumption of petroleum amount, global atmosphere pollution 42%
From in the discharge of vehicular traffic.On June 1st, 2010, four ministries and commissions such as National Development and Reform Committee joint are put into effect " new about the private purchase of development
The notice of energy automobile subsidy pilot ", it determines in Shanghai, Changchun, Shenzhen, Hangzhou, the private new energy of purchase of 5, Hefei city starting
Source automobile subsidizes pilot.On July 12nd, 2013, Premier of the State Council Li Keqiang hold Executive Meeting of the State Council, propose government
Car for public affairs, bus take the lead in promoting the use of new-energy automobile, highlight support of the central government to new-energy automobile once again.Generation
Various countries, boundary pay much attention to Development of EV, will also develop electric vehicle in China's 863 Program and are classified as important development direction.As
The research of the power battery of onboard power becomes the main bottleneck of power vehicle development.The main candidate of current driving force battery
There are nickel-metal hydride battery, lithium ion battery and fuel cell.Based on the considerations of cost performance, lithium ion battery is had great advantages.Lithium
Ion battery has that voltage is high, specific capacity is big, has extended cycle life and has a safety feature as energy storage material compared to conventional batteries
Advantage is widely used in the fields such as portable electronic device, electric car, aerospace and military engineering, has wide
Application prospect and huge economic benefit.
Lithium ion battery has energy density height, average output electricity as a kind of environmentally protective high-performance secondary cell
Press height, the advantages that output power, self discharge is small, efficiency for charge-discharge is high, memory-less effect, various portable electronic products,
It is more and more applied in communication tool, electric car and hybrid vehicle.Lithium ion battery since commercialization,
The research of positive electrode is the hot spot of the area research always.The positive electrode of lithium ion battery mainly have cobalt acid lithium, LiMn2O4,
Lithium nickelate, ternary material, LiFePO4 etc..Wherein LiFePO4 have it is nontoxic, pollution-free, have a safety feature, raw material sources
Extensively, cheap, the advantages that service life is long, become the ideal positive electrode of lithium ion battery of new generation.Synthesizing iron lithium phosphate
Common method have high temperature solid-state method, sol-gel method and hydro-thermal method etc..Though these types of method has their own advantages, there is also one
A little apparent defects.Such as, the partial size of high temperature solid-state method synthesizing iron lithium phosphate particle is larger, and charge-discharge performance is not satisfactory；Colloidal sol-
The technique of gel method is relative complex, and production cost is higher；Though hydro-thermal method can control partial size, industrial difficulty is larger.Separately
On the one hand, LiFePO4 itself poorly conductive, when lithium ion diffusion causes battery high power charging-discharging slowly, actual specific capacity is low,
The disadvantages of charge rate is slow, and cruising ability is short, these disadvantages also counteract the application of LiFePO 4 material.
Therefore, it is quite necessary to develop new composite ferric lithium phosphate material and its technology of preparing to improve the comprehensive of LiFePO4
Performance is closed, its heavy industrialization application is promoted.
Summary of the invention
For overcome the deficiencies in the prior art, the purpose of the present invention is to provide a kind of high-energy density lithium battery ferric phosphates
The preparation method of lithium anode material, the lithium iron phosphate positive material actual specific capacity height of preparation, good conductivity, charge rate be fast,
Cruising ability is strong.
To achieve the purpose of the present invention, the present invention adopts the following technical scheme:
The technical scheme to solve the above technical problems is that a kind of high-energy density lithium battery iron phosphate lithium positive pole
The preparation method of material comprising following steps:
(1) spinning solution of polyacrylonitrile containing lithium salts is prepared: the polypropylene that concentration is 5~15wt% is added in lithium salts and phosphoric acid
In the DMF solution of nitrile, the mass ratio of the DMF solution of lithium and polyacrylonitrile is 3~10:100 in lithium salts, phosphoric acid and polyacrylonitrile
The mass ratio of DMF solution is 0.5~1.5:100, and rear deaeration is sufficiently stirred, obtains the spinning solution of polyacrylonitrile containing lithium salts；
(2) spinning solution of polyacrylonitrile containing ferrous salt is prepared: preparation method and raw material dosage are identical as step (1), only will
Lithium salts replaces with ferrous salt, obtains the spinning solution of polyacrylonitrile containing ferrous salt；
(3) lithium salts polyacrylonitrile spinning solution and molysite polypropylene the electrostatic spinning preparation of nano fiber non-woven fabric: will be contained
Nitrile spinning solution is injected separately into two spinning syringes and is placed in spinning equipment, horizontal electrospinning, adjustment voltage be 10~
30kV；The distance of two independent spinning heads to roller reception device is 10~30cm；When electrostatic spinning, two spinning head spinning
The flow of solution is 1~3mL/h, and the rotation speed of roller reception device is 50~150rad/min, after the completion of electrostatic spinning,
Nano fiber non-woven fabric is collected into the reception device of rotation；
(4) carbonization of nano fiber non-woven fabric: by nano fiber non-woven fabric in air 275~285 DEG C pre-oxidation 1.5~
2.5h, in N2Under atmosphere, 800~900 DEG C are warming up to the speed of 1.5~2.5 DEG C/min and keeps 5~8h, in N2Under atmosphere certainly
It is so cooled to room temperature, obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes: it is 5 that LiFePO4 carbon nano-composite material, which is added to concentration,
In the manganese salt solution of~15wt%, the mass ratio of manganese is 1:1 in LiFePO4 carbon nano-composite material and manganese salt solution, is surpassed
Sound disperses 5~10h, takes out drying；In N2Under atmosphere, the material after drying is warming up to the speed of 1.5~2.5 DEG C/min
800~900 DEG C and 5~8h of holding, in N2Cooled to room temperature is under atmosphere to get LiFePO4 carbon nano anode material.
Based on the above technical solution, the present invention can also be improved as follows.
Preferably, the spinning solution of polyacrylonitrile containing lithium salts and polypropylene containing ferrous salt obtained in step (1) and step (2)
Lithium ion is identical as the concentration of ferrous ion in nitrile spinning solution.
Specifically, the process for preparation of the DMF solution of the polyacrylonitrile is as follows: polyacrylonitrile is dissolved in DMF, 70~
At 80 DEG C stir 15~20h to get.
Preferably, the lithium salts is the mixing of one or both of lithium nitrate and lithium acetate arbitrary proportion.
Preferably, the ferrous salt is one of ferrous nitrate, ferrous acetate and ferrous sulfate or a variety of arbitrary proportions
Mixing.
Preferably, the mumber average molar mass of the polyacrylonitrile is 1.5 × 105~2.5 × 105g·mol-1。
Preferably, the manganese salt is the mixing of manganese acetate, manganese sulfate and any one or more of arbitrary proportion of manganese nitrate.
In addition, passing through the above method the present invention also provides a kind of high-energy density lithium battery lithium iron phosphate positive material
It is prepared.
Compared with prior art, the beneficial effects of the present invention are:
(1) polyacrylonitrile solution for preparing lithium salts and ferrous salt respectively, is then handed over by the method for electrostatic spinning again
It is wrong uniformly compound, can guarantee the stable homogeneous of lithium iron phosphate positive material, while lithium salts and molysite be it is separated, be conducive to
Raw materials recovery；
(2) in preparation process nano fiber non-woven fabric carburising step, be conducive to improve connecing for LiFePO4 and electrolyte
Contacting surface product improves charge rate, and the polyacrylonitrile after carbonization, further promotes the gram volume and electric conductivity of material.
(3) in post-processing step, by adulterating suitable manganese in LiFePO 4 material lattice, material can be improved
Average voltage, to promote the energy density of material.
(4) preparation method of offer of the invention, simple process and low cost is high-efficient, safety and environmental protection, is suitble to scale
Production.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of roller collection device and the spinning syringe for its two sides of living apart when carrying out electrostatic spinning；
Fig. 2 is the SEM figure of LiFePO4 carbon nano anode material prepared by the embodiment of the present invention 1.
Specific embodiment
Technical solution provided by the invention is described in further detail below in conjunction with drawings and the specific embodiments, is lifted
Example is served only for explaining the present invention, is not intended to limit the scope of the present invention.
Embodiment 1
A kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material, includes the following steps:
(1) preparation of the spinning solution of polyacrylonitrile containing lithium salts
It (a) is 1.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide
In solvent (DMF), 15h is stirred at 70 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 5%；
(b) lithium nitrate and phosphoric acid are added in polyacrylonitrile solution, the quality of lithium and polyacrylonitrile solution in lithium nitrate
Than for 6:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 8h, ultrasonic deaeration 20min, obtain uniformly
The transparent spinning solution of polyacrylonitrile containing lithium salts；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
It (c) is 1.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide
In solvent, 15h is stirred at 70 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 5%；
(d) ferrous nitrate and phosphoric acid are added in polyacrylonitrile solution, ferrous and polyacrylonitrile solution in ferrous nitrate
Mass ratio be 3:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 0.5:100, magnetic agitation 8h, ultrasonic deaeration 20min,
Obtain the spinning solution of polyacrylonitrile containing ferrous salt of homogeneous transparent；
(3) electrospun nanofibers film
Lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into two spinning syringes,
It is placed in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 10kV；Two independent spinning heads arrive
The distance of roller reception device is 10cm；The flow of spinning head spinning solution is 1mL/h, and the rotation speed of roller reception device is
50rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in the reception device of rotation
It is collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
By nanofiber 280 DEG C of pre-oxidation 2h in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 800 DEG C
And 5h is kept, in N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes
(e) LiFePO4 carbon nano-composite material made from step (4) is added to the manganese acetate water that mass fraction is 5%
In solution, the mass ratio of LiFePO4 carbon nano-composite material and the water-soluble middle manganese of manganese acetate is 1:1, ultrasonic disperse 5h, takes out and dries
It is dry；
(f) in N2Under atmosphere, step (e) is obtained into material with 2 DEG C of min-1Speed be warming up to 800 DEG C and keep 5h,
N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano anode material.
LiFePO4 carbon nano anode material scanning electron microscopic observation its surface topography that embodiment 1 is prepared, knot
Fruit is as shown in Fig. 2, its microscopic dimensions is more uniform as seen from the figure.
Embodiment 2
A kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material, includes the following steps:
(1) preparation of the spinning solution of polyacrylonitrile containing lithium salts
It (a) is 2 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, N '-dimethyl formamide solvent
In, 18h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 10%；
(b) lithium acetate and phosphoric acid are added in polyacrylonitrile solution, the quality of lithium and polyacrylonitrile solution in lithium acetate
Than for 3:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 0.5:100, magnetic agitation 10h, and ultrasonic deaeration 25min is obtained
The spinning solution of polyacrylonitrile containing lithium salts of homogeneous transparent；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
It (c) is 2 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, N '-dimethyl formamide solvent
In, 18h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 10%；
(d) ferrous acetate and phosphoric acid are added in polyacrylonitrile solution, ferrous and polyacrylonitrile solution in ferrous acetate
Mass ratio be 6:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 10h, ultrasonic deaeration 25min,
Obtain the spinning solution of polyacrylonitrile containing ferrous salt of homogeneous transparent；
(3) electrospun nanofibers film
Lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into spinning syringe, put
In in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 20kV；Two independent spinning heads are to roller
The distance of reception device is 20cm；The flow of spinning head spinning solution is 2mL/h, and the rotation speed of roller reception device is
100rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in the reception device of rotation
On be collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
By nanofiber 280 DEG C of pre-oxidation 2h in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 850 DEG C
And 6h is kept, in N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes
(e) LiFePO4 carbon nano-composite material made from step (4) is added to the manganese sulfate that mass fraction is 10%
In aqueous solution, the mass ratio of manganese is 1:1, ultrasonic disperse 8h in LiFePO4 carbon nano-composite material and manganese salt solution, is taken out
Drying；
(f) in N2Under atmosphere, step (e) is obtained into material with 2 DEG C of min-1Speed be warming up to 850 DEG C and keep 6h,
N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano anode material.
Embodiment 3
A kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material, includes the following steps:
(1) preparation of the spinning solution of polyacrylonitrile containing lithium salts
It (a) is 2 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, N '-dimethyl formamide solvent
In, 15h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 15%；
(b) lithium nitrate and phosphoric acid are added in polyacrylonitrile solution, the quality of lithium and polyacrylonitrile solution in lithium nitrate
Than for 8:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1.5:100, magnetic agitation 12h, and ultrasonic deaeration 30min is obtained
The spinning solution of polyacrylonitrile containing lithium salts of homogeneous transparent；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
It (c) is 2 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, N '-dimethyl formamide solvent
In, 15h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 15%；
(d) ferrous sulfate and phosphoric acid are added in polyacrylonitrile solution, ferrous and polyacrylonitrile solution in ferrous sulfate
Mass ratio be 8:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1.5:100, magnetic agitation 12h, ultrasonic deaeration
30min obtains the spinning solution of polyacrylonitrile containing ferrous salt of homogeneous transparent；
(3) electrospun nanofibers film
Lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into spinning syringe, put
In in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 30kV；Two independent spinning heads are to roller
The distance of reception device is 30cm；The flow of spinning head spinning solution is 3mL/h, and the rotation speed of roller reception device is
150rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in the reception device of rotation
On be collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
By nanofiber 280 DEG C of pre-oxidation 2h in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 900 DEG C
And 8h is kept, in N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes
(e) LiFePO4 carbon nano-composite material made from step (4) is added to the manganese nitrate that mass fraction is 15%
In aqueous solution, the mass ratio of manganese is 1:1, ultrasonic disperse 10h in LiFePO4 carbon nano-composite material and manganese salt, takes out drying；
(f) in N2Under atmosphere, step (e) is obtained into material with 2 DEG C of min-1Speed be warming up to 900 DEG C and keep 8h,
N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano anode material.
Embodiment 4
A kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material, includes the following steps:
(1) preparation of the spinning solution of polyacrylonitrile containing lithium salts
It (a) is 2.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, and N '-dimethyl formamide is molten
In agent, 18h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 10%；
(b) lithium acetate and phosphoric acid are added in polyacrylonitrile solution, the quality of lithium and polyacrylonitrile solution in lithium acetate
Than for 10:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 10h, ultrasonic deaeration 25min, obtain
The even transparent spinning solution of polyacrylonitrile containing lithium salts；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
It (c) is 2.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder is dissolved in N, and N '-dimethyl formamide is molten
In agent, 18h is stirred at 75 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 10%；
(d) ferrous sulfate and phosphoric acid are added in polyacrylonitrile solution, ferrous and polyacrylonitrile solution in ferrous sulfate
Mass ratio be 10:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1.5:100, magnetic agitation 10h, ultrasonic deaeration
25min obtains the spinning solution of polyacrylonitrile containing ferrous salt of homogeneous transparent；
(3) electrospun nanofibers film
Lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into spinning syringe, put
In in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 25kV；Two independent spinning heads are to roller
The distance of reception device is 25cm；The flow of spinning head spinning solution is 2mL/h, and the rotation speed of roller reception device is
100rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in the reception device of rotation
On be collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
By nanofiber 280 DEG C of pre-oxidation 2h in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 900 DEG C
And 5h is kept, in N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes
(e) LiFePO4 carbon nano-composite material made from step (4) is added to the manganese acetate that mass fraction is 10%
In aqueous solution, the mass ratio of manganese is 1:1, ultrasonic disperse 8h in LiFePO4 carbon nano-composite material and manganese salt, takes out drying；
(f) in N2Under atmosphere, step (e) is obtained into material with 2 DEG C of min-1Speed be warming up to 900 DEG C and keep 8h,
N2Cooled to room temperature under atmosphere obtains LiFePO4 carbon nano anode material.
Comparative example 1
A kind of lithium iron phosphate positive material, preparation method include the following steps:
(1) preparation of the spinning solution of polyacrylonitrile containing lithium salts
It (a) is 1.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide
In solvent, 15h is stirred at 70 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 5%；
(b) lithium nitrate and phosphoric acid are added in polyacrylonitrile solution, the quality of lithium and polyacrylonitrile solution in lithium nitrate
Than for 6:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 8h, ultrasonic deaeration 20min, obtain uniformly
The transparent spinning solution of polyacrylonitrile containing lithium salts；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
It (c) is 1.5 × 10 by mumber average molar mass5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide
In solvent, 15h is stirred at 70 DEG C, is configured to the polyacrylonitrile solution that mass fraction is 5%；
(d) ferrous nitrate and phosphoric acid are added in polyacrylonitrile solution, ferrous and polyacrylonitrile solution in ferrous nitrate
Mass ratio be 3:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 0.5:100, magnetic agitation 8h, ultrasonic deaeration 20min,
Obtain the spinning solution of polyacrylonitrile containing ferrous salt of homogeneous transparent；
(3) electrospun nanofibers non-woven fabrics
Lithium salts polyacrylonitrile spinning solution will be contained and molysite polyacrylonitrile spinning solution is injected separately into spinning syringe, put
In in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 10kV；Two independent spinning heads are to roller
The distance of reception device is 10cm；The flow of spinning head spinning solution is 1mL/h, and the rotation speed of roller reception device is
50rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in the reception device of rotation
It is collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
By nanofiber 280 DEG C of pre-oxidation 2h in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 800 DEG C
And 5h is kept, in N2Cooled to room temperature under atmosphere, obtains lithium iron phosphate positive material.
Performance detection:
| Detection project | Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | Comparative example 1 |
| Gram volume (mAh/g) | 160 | 160.5 | 161 | 160.5 | 150 |
| Compacted density (g/cm3) | 2.39 | 2.40 | 2.41 | 2.40 | 2.29 |
| Cycle life (secondary) | 2200 | 2200 | 2200 | 2200 | 2000 |
| Capacity retention ratio | 89% | 90% | 91% | 90% | 80% |
As seen from the above table, the available gram volume of preparation method provided by the invention is high, compacted density is big, has extended cycle life
The lithium iron phosphate positive material with practical value of high function admirable with capacity retention ratio；Comparative example 1 and 1 phase of embodiment
Than lacking the post-processing of manganese salt solution, the performance for the positive electrode that Cong Shangbiao visual contrast example 1 obtains is decreased obviously.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (8)
1. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material, which comprises the steps of:
(1) spinning solution of polyacrylonitrile containing lithium salts is prepared: the polyacrylonitrile that concentration is 5~15wt% is added in lithium salts and phosphoric acid
In DMF solution, the mass ratio of the DMF solution of lithium and polyacrylonitrile in lithium salts is 3~10:100, phosphoric acid and polyacrylonitrile
The mass ratio of DMF solution is 0.5~1.5:100, and rear deaeration is sufficiently stirred, obtains the spinning solution of polyacrylonitrile containing lithium salts；
(2) spinning solution of polyacrylonitrile containing ferrous salt is prepared: the polypropylene that concentration is 5~15wt% is added in ferrous salt and phosphoric acid
In the DMF solution of nitrile, the mass ratio of the DMF solution of iron and polyacrylonitrile in ferrous salt is 3~10:100, phosphoric acid and polypropylene
The mass ratio of the DMF solution of nitrile is 0.5~1.5:100, and rear deaeration is sufficiently stirred, obtains the spinning solution of polyacrylonitrile containing ferrous salt；
(3) lithium salts polyacrylonitrile spinning solution and polypropylene containing ferrous salt the electrostatic spinning preparation of nano fiber non-woven fabric: will be contained
Nitrile spinning solution is injected separately into two spinning syringes and is placed in spinning equipment, horizontal electrospinning, adjustment voltage be 10~
30kV；The distance of two independent spinning heads to roller reception device is 10~30cm；When electrostatic spinning, two spinning head spinning
The flow of solution is 1~3mL/h, and the rotation speed of roller reception device is 50~150rad/min, after the completion of electrostatic spinning,
Nano fiber non-woven fabric is collected into the reception device of rotation；
(4) carbonization of nano fiber non-woven fabric: by nano fiber non-woven fabric in air 275~285 DEG C pre-oxidation 1.5~
2.5h, in N2Under atmosphere, 800~900 DEG C are warming up to the speed of 1.5~2.5 DEG C/min and keeps 5~8h, in N2Under atmosphere certainly
It is so cooled to room temperature, obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-process: by LiFePO4 carbon nano-composite material be added to concentration be 5~
In the manganese salt solution of 15wt%, the mass ratio of manganese is 1:1, ultrasound in LiFePO4 carbon nano-composite material and manganese salt solution
Disperse 5~10h, takes out drying；In N2Under atmosphere, the material after drying is warming up to 800 with the speed of 1.5~2.5 DEG C/min
~900 DEG C and 5~8h of holding, in N2Cooled to room temperature is under atmosphere to get lithium iron phosphate positive material.
2. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is, the matter of lithium ion and ferrous ion in the spinning solution of polyacrylonitrile containing lithium salts and the spinning solution of polyacrylonitrile containing ferrous salt
It is identical to measure concentration.
3. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is that the process for preparation of the DMF solution of the polyacrylonitrile is as follows: polyacrylonitrile being dissolved in DMF, is stirred at 70~80 DEG C
Mix 15~20h to get.
4. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is that the lithium salts is the mixing of one or both of lithium nitrate and lithium acetate arbitrary proportion.
5. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is that the ferrous salt is the mixing of one of ferrous nitrate, ferrous acetate and ferrous sulfate or a variety of arbitrary proportions.
6. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is that the mumber average molar mass of the polyacrylonitrile is 1.5 × 105~2.5 × 105g·mol-1。
7. a kind of preparation method of high-energy density lithium battery lithium iron phosphate positive material according to claim 1, special
Sign is that the manganese salt is the mixing of manganese acetate, manganese sulfate and any one or more of arbitrary proportion of manganese nitrate.
8. a kind of high-energy density lithium battery lithium iron phosphate positive material, which is characterized in that pass through any one of claim 1 to 7
The method is prepared.
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| CN101964418A (en) * | 2010-09-28 | 2011-02-02 | 彩虹集团公司 | Method for preparing lithium iron phosphate-doped nano powder for lithium ion battery |
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| CN101964418A (en) * | 2010-09-28 | 2011-02-02 | 彩虹集团公司 | Method for preparing lithium iron phosphate-doped nano powder for lithium ion battery |
| CN102392311A (en) * | 2010-11-08 | 2012-03-28 | 长春劲能锂电池科技有限公司 | Method for synthesizing lithium iron phosphate material by adopting electrostatic spinning |
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