CN108598474A - 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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Abstract
The present invention relates to a kind of high-energy density lithium battery lithium iron phosphate positive materials and preparation method thereof, which includes the following steps:(1) spinning solution of polyacrylonitrile containing lithium salts is prepared；(2) spinning solution of polyacrylonitrile containing ferrous salt is prepared；(3) prepared by the electrostatic spinning 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, carries out a series of follow-up 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-processes, and 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 ferric phosphate
Lithium anode material and preparation method thereof belongs to power battery technology field.
Background technology
21 century facing mankind two Tough questions of energy crisis and environmental pollution, therefore cleans renewable new energy
Exploitation with research have far reaching significance.Wherein, all kinds of automobiles account for 40% or so of consumption of petroleum amount, global atmosphere pollution
42% comes from the discharge of vehicular traffic.Development of EV is paid much attention in countries in the world, also will hair in China's 863 Program
Exhibition electric vehicle is classified as important development direction.The research of power battery as onboard power becomes the main of power vehicle development
Bottleneck.The main candidate of current driving force battery has Ni-MH battery, lithium ion battery and fuel cell.Examining based on cost performance
Consider, lithium ion battery has larger advantage.Lithium ion battery has voltage height, ratio as energy storage material compared to conventional batteries
Capacity is big, the advantages of having extended cycle life and having a safety feature, and is widely used in portable electronic device, electric vehicle, aviation
The fields such as space flight and military engineering have broad application prospects 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 vehicle and hybrid vehicle.Lithium ion battery from commercialization with
Come, the research of positive electrode is the hot spot of the area research always.The positive electrode of lithium ion battery mainly has cobalt acid lithium, manganese
Sour lithium, lithium nickelate, ternary material, LiFePO4 etc..Wherein LiFePO4 have it is nontoxic, pollution-free, have a safety feature, former material
The advantages that material derives from a wealth of sources, is cheap, long lifespan, becomes the ideal positive electrode of lithium ion battery of new generation.Synthesis
The common method of LiFePO4 has 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 some apparent defects.Such as, the grain size of high temperature solid-state method synthesizing iron lithium phosphate particle is larger, and charge-discharge performance is less
It is ideal；The technique of sol-gel method is relative complex, and production cost is higher；Though hydro-thermal method can control grain size, industrial
Difficulty is larger.On the other hand, LiFePO4 itself poorly conductive, it is real when lithium ion diffusion causes battery high power charging-discharging slowly
The shortcomings of border specific capacity is low, and 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 LiFePO4
Comprehensive performance promotes its heavy industrialization application.
Invention content
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 phosphoric acid
The preparation method of iron lithium anode material, the practical specific volume height of lithium iron phosphate positive material 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 that：
The technical solution that the present invention solves above-mentioned technical problem is as follows：A kind of high-energy density lithium battery LiFePO4 is just
The preparation method of pole material comprising following steps：
(1) spinning solution of polyacrylonitrile containing lithium salts is prepared：Lithium salts and phosphoric acid are added poly- the third of a concentration of 5~15wt%
In the DMF solution of alkene nitrile, the mass ratio of the DMF solution of lithium and polyacrylonitrile is 3~10 in lithium salts:100, phosphoric acid and polypropylene
The mass ratio of the DMF solution of nitrile is 0.5~1.5:100, it is sufficiently stirred rear deaeration, 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) prepared by the electrostatic spinning of nano fiber non-woven fabric：Lithium salts polyacrylonitrile spinning solution and molysite polypropylene 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 heads are spun
The flow of silk solution is 1~3mL/h, and the rotary speed of roller reception device is 50~150rad/min, and electrostatic spinning is completed
Afterwards, it is collected into nano fiber non-woven fabric in the reception device of rotation；
(4) carbonization of nano fiber non-woven fabric：By nano fiber non-woven fabric 275~285 DEG C of pre-oxidation 1.5 in air
~2.5h, in N2Under atmosphere, it is warming up to 800~900 DEG C with the speed of 1.5~2.5 DEG C/min and keeps 5~8h, in N2Atmosphere
Lower cooled to room temperature, obtains LiFePO4 carbon nano-composite material；
(5) LiFePO4 carbon nano-composite material post-processes：LiFePO4 carbon nano-composite material is added to a concentration of
In the manganese salt solution of 5~15wt%, the mass ratio of LiFePO4 carbon nano-composite material and manganese in manganese salt solution is 1:1,
5~10h of ultrasonic disperse takes out drying；In N2Under atmosphere, the material after drying is heated up with the speed of 1.5~2.5 DEG C/min
To 800~900 DEG C and 5~8h is kept, in N2Cooled to room temperature is to get LiFePO4 carbon nano anode material under atmosphere.
Based on the above technical solution, the present invention can also be improved as follows.
Preferably, the spinning solution of polyacrylonitrile containing lithium salts that is obtained in step (1) and step (2) and contain ferrous salt poly- third
Lithium ion is identical as the concentration of ferrous ion in alkene 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 or more arbitrary proportions in ferrous nitrate, ferrous acetate and ferrous sulfate
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 mixed of manganese acetate, manganese sulfate and manganese nitrate any one or more of arbitrary proportion
It closes.
In addition, the present invention also provides a kind of high-energy density lithium battery lithium iron phosphate positive material, pass through the above method
It is prepared.
Compared with prior art, the beneficial effects of the invention are as follows：
(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 ensure the stable homogeneous of lithium iron phosphate positive material, while lithium salts and molysite be it is separated, favorably
In 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 is accumulated, and is improved charge rate, and the polyacrylonitrile after carbonization, is further promoted 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 efficient, safety and environmental protection, is suitble to scale
Production.
Description of the drawings
Fig. 1 is the structural schematic diagram of roller collection device and the spinning syringe for its both sides of living apart when carrying out electrostatic spinning；
Fig. 2 is the SEM figures of LiFePO4 carbon nano anode material prepared by the embodiment of the present invention 1.
Specific implementation mode
Technical solution provided by the invention is described in further detail below in conjunction with drawings and the specific embodiments, institute
It gives an actual example and is served only for explaining the present invention, be 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
(a) it is 1.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide solvent
(DMF) in, 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 being 6:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 8 h, ultrasonic deaeration 20min are obtained
The even transparent spinning solution of polyacrylonitrile containing lithium salts；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
(c) it is 1.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide solvent
In, 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 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 two spinning injections
Device is placed in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), and adjustment voltage is 10kV；Two independent spinnerets
The distance of head to roller reception device is 10cm；The flow of spinning head spinning solution is 1mL/h, the rotation of roller reception device
Speed is 50rad/min, while the reception device for starting two device for spinning and rotation carries out electrostatic spinning, in connecing for rotation
Nano fiber non-woven fabric is collected on receiving apparatus；
(4) carbonization of nano fiber non-woven fabric
Nanofiber is pre-oxidized into 2h for 280 DEG C in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 800
DEG C and keep 5h, 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 5%
In aqueous 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 take out
Drying；
(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
(a) it is 2 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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 being 3:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 0.5:100, magnetic agitation 10h, ultrasonic deaeration 25min are obtained
The spinning solution of polyacrylonitrile containing lithium salts of homogeneous transparent；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
(c) it is 2 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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
It is put in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 20kV；Two independent spinning heads to rolling
The distance of cylinder reception device is 20cm；The flow of spinning head spinning solution is 2mL/h, and the rotary 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
Nanofiber is pre-oxidized into 2h for 280 DEG C in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 850
DEG C and keep 6h, 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 LiFePO4 carbon nano-composite material and manganese in manganese salt solution is 1:1, ultrasonic disperse 8h take 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
(a) it is 2 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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 being 8:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1.5:100, magnetic agitation 12h, ultrasonic deaeration 30min are obtained
The spinning solution of polyacrylonitrile containing lithium salts of homogeneous transparent；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
(c) it is 2 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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
It is put in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 30kV；Two independent spinning heads to rolling
The distance of cylinder reception device is 30cm；The flow of spinning head spinning solution is 3mL/h, and the rotary 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
Nanofiber is pre-oxidized into 2h for 280 DEG C in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 900
DEG C and keep 8h, 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 LiFePO4 carbon nano-composite material and manganese in manganese salt is 1:1, ultrasonic disperse 10h take 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
(a) it is 2.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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 being 10:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 10h, ultrasonic deaeration 25min are obtained
The spinning solution of polyacrylonitrile containing lithium salts of homogeneous transparent；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
(c) it is 2.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder is dissolved in N, in N '-dimethyl formamide solvent,
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
It is put in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 25kV；Two independent spinning heads to rolling
The distance of cylinder reception device is 25cm；The flow of spinning head spinning solution is 2mL/h, and the rotary 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
Nanofiber is pre-oxidized into 2h for 280 DEG C in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 900
DEG C and keep 5h, 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 LiFePO4 carbon nano-composite material and manganese in manganese salt is 1:1, ultrasonic disperse 8h take 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
(a) it is 1.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide solvent
In, 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 being 6:100, the mass ratio of phosphoric acid and polyacrylonitrile solution is 1:100, magnetic agitation 8 h, ultrasonic deaeration 20min are obtained
The even transparent spinning solution of polyacrylonitrile containing lithium salts；
(2) preparation of the spinning solution of polyacrylonitrile containing ferrous salt
(c) it is 1.5 × 10 by molecular weight5g·mol-1Polyacrylonitrile powder be dissolved in N, N '-dimethyl formamide solvent
In, 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 obtains 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
It is put in spinning equipment, horizontal electrospinning (schematic device such as Fig. 1), adjustment voltage is 10kV；Two independent spinning heads to rolling
The distance of cylinder reception device is 10cm；The flow of spinning head spinning solution is 1mL/h, and the rotary 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
On be collected into nano fiber non-woven fabric；
(4) carbonization of nano fiber non-woven fabric
Nanofiber is pre-oxidized into 2h for 280 DEG C in air, in N2Under atmosphere, with 2 DEG C of min-1Speed be warming up to 800
DEG C and keep 5h, 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, preparation method provided by the invention can obtain that gram volume is high, compacted density is big, cycle life
Long and the high function admirable of capacity retention ratio the lithium iron phosphate positive material with practical value；Comparative example 1 and embodiment 1
It compares, lacks the post-processing of manganese salt solution, the performance of the positive electrode obtained from upper table visual contrast example 1 is decreased obviously.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all the present invention spirit and
Within principle, any modification, equivalent replacement, improvement and so on 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 is characterized in that include the following steps：
(1) spinning solution of polyacrylonitrile containing lithium salts is prepared：Lithium salts and phosphoric acid are added to the polyacrylonitrile of a concentration of 5~15wt%
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, it is sufficiently stirred rear deaeration, obtains the spinning solution of polyacrylonitrile containing lithium salts；
(2) spinning solution of polyacrylonitrile containing ferrous salt is prepared：Ferrous salt and phosphoric acid are added to the polypropylene of a concentration of 5~15wt%
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, it is sufficiently stirred rear deaeration, obtains the spinning solution of polyacrylonitrile containing ferrous salt；
(3) prepared by the electrostatic spinning of nano fiber non-woven fabric：Lithium salts polyacrylonitrile spinning solution and polypropylene containing ferrous salt 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 rotary speed of roller reception device is 50~150rad/min, after the completion of electrostatic spinning,
It is collected into nano fiber non-woven fabric in 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, it is warming up to 800~900 DEG C with 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：LiFePO4 carbon nano-composite material is added to a concentration of 5~
In the manganese salt solution of 15wt%, the mass ratio of LiFePO4 carbon nano-composite material and manganese in manganese salt solution is 1:1, ultrasound
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 to get lithium iron phosphate positive material under atmosphere.
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 is 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 or more arbitrary proportions in ferrous nitrate, ferrous acetate and ferrous sulfate.
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 manganese nitrate any one or more of arbitrary proportion.
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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| CN111224086A (en) * | 2020-01-15 | 2020-06-02 | 东华大学 | Preparation of iron-doped lithium manganese phosphate/carbon composite nanofiber cathode material |
| CN113809424A (en) * | 2021-08-25 | 2021-12-17 | 广东邦普循环科技有限公司 | Method for recycling mixed waste of lithium nickel cobalt manganese oxide and lithium iron phosphate |
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