CN105374984A - Hetero-nanostructure lithium manganese phosphate/carbon composite material and preparation method therefor - Google Patents

Hetero-nanostructure lithium manganese phosphate/carbon composite material and preparation method therefor Download PDF

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CN105374984A
CN105374984A CN201410427809.2A CN201410427809A CN105374984A CN 105374984 A CN105374984 A CN 105374984A CN 201410427809 A CN201410427809 A CN 201410427809A CN 105374984 A CN105374984 A CN 105374984A
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lithium
preparation
manganese
carbon
phosphate
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张龙飞
郑洪河
沈鸣
张先林
沈锦良
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JIANGSU HUASHENG CHEMICALS CO Ltd
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JIANGSU HUASHENG CHEMICALS CO Ltd
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention relates to a hetero-nanostructure lithium manganese phosphate/carbon composite material and a preparation method therefor. The preparation method comprises the steps of (1) mixing a surfactant with an organic solvent at the volume ratio of 1:10-1:2 to form a mixed solution; (2) adding a lithium source compound, a manganese source compound and a phosphorus source compound into the mixed solution obtained in the step (1), and then adding an organic carbon source, wherein the carbon element accounts for 1-20% of the composite material in mass; (3) performing ball milling in a ball-milling pot; (4) stirring the ball-milled product at the temperature of 50-80 DEG C until the product is fully dried by evaporation, then putting the product in an inert atmosphere at the temperature of 300-400 DEG C for pre-processing for 2-10 hours; and (5) fully grinding the pre-processed product, pressing the product at the pressure of 15-30 atm cm<-2>, and calcining the product under the protection of the inert atmosphere at the temperature of 550-750 DEG C for 2-10 hours to obtain the hetero-nanostructure lithium manganese phosphate/carbon composite material. The preparation method is simple in process and favorable for realizing the industrial production.

Description

Heterogeneous nano lithium manganese phosphate of lithium/carbon composite and preparation method thereof
Technical field
The invention belongs to technical field of lithium ion battery positive pole material preparation, be specifically related to a kind of heterogeneous nano lithium manganese phosphate of lithium/carbon composite and preparation method thereof.
Technical background
The progress of positive electrode and optimization promote the key of lithium ion battery technology to safety, environmental protection, low cost, high-energy-density and high power density future development.Extensively the positive electrode of investigation and application mainly contains the LiMO of layer structure at present 2the LiMn of (M=Co, Ni or Mn) and spinel structure 2o 4.But this several positive electrode all has respective shortcoming:
(1) LiCoO 2scarcity of resources, cost are high, toxicity is large;
(2) LiNiO 2preparation condition is harsh, thermally-stabilised difference; With
(3) LiMn 2o 4theoretical capacity is not high, and dissolves and Jahn-Teller effect due to manganese, causes the cyclical stability of material circulation performance especially under high temperature to be greatly affected.
At present, with LiFePO 4transition metal phosphate positive electrode for representative has the feature of aboundresources, cheap, environmental friendliness, high cyclical stability and fail safe.Therefore, it has developed into the focus of people's research.The LiFePO that carbon is coated 4positive electrode has obtained good commercialization, becomes the ideal chose of high capacity cell positive electrode.LiMnPO 4with LiFePO 4have highly stable olivine structural equally, theoretical capacity is 170mAhg -1, there is higher voltage platform (4.1VvsLi +/ Li), theoretical energy density compares LiFePO 4improve 20%, and voltage platform is in the stability window of existing carbonate group electrolyte system, ensure that the security performance of battery, therefore LiMnPO 4material shows significant application prospect in power lithium-ion battery field.
But, LiMnPO 4extremely low electronic conductivity and ionic conductivity have impact on the chemical property of material.The people such as hillside plot (Yamada) calculate LiMnPO by first principle to electron energy level 4electron transition energy gap be 2eV, almost belong to insulator category.The current method improving material olivine crystallographic system material electrochemical activity mainly contains:
1) carbon is coated;
2) particle nanometer; With
3) ion doping.
Wherein, the coated and ion doping of carbon can effectively improve between material granule and particle and the electronic conductivity of material itself respectively, and particle nanometer can shorten the diffusion length of lithium ion in granule interior, minimizing lithium ion diffusion time.
Research shows, only has and works as LiMnPO 4particle scale control the diffusion requirement that could meet lithium ion at below 100nm.But when particle is reduced to this yardstick, realizes uniform carbon and be overmolding in order to new challenge.Therefore, need a kind of new synthetic method, realize LiMnPO 4particle nanometer and carbon coated.At LiMnPO 4building three-dimensional conductive network between particle is a kind of new thinking.
The people such as Cao (Cao) utilize MnO (acac) 2(metal oxygen ethylacetoacetone acid manganese) is manganese source and carbon source, LiH 2pO 4for lithium source and phosphorus source, prepare high performance LiMnPO by solid phase reaction 4/ C composite.MnO (acac) in building-up process 2be decomposed to form the structure of carbon coated manganese source presoma, then by with LiH 2pO 4reaction generates the LiMnPO of nucleocapsid structure 4, and the original position of carbon coating layer forms the growth and the reunion that inhibit particle well, and grain diameter has controlled to below 20nm.This material 0.1C and 1C multiplying power discharging reach 140 and 120mAhg respectively -1.
Persons such as remaining (Yu) as lithium source and carbon source, adopts solvent structure LiMnPO with different organic lithium salts 4nano composite material.When experiment discovery lithium benzoate is as lithium salts, the performance obtaining material is best.In heat of solution course of reaction, the decomposition in situ of lithium benzoate generates unbodied carbon and is coated on LiMnPO 4surface, effectively inhibit the reunion of material in high-temperature burning process.Material is 130mAhg at 0.1C multiplying power discharging capacity -1, it is 89% that 1C circulation 50 encloses capability retention.
Although the material electrochemical performance of above-mentioned these methods synthesis is better, still Shortcomings part:
(1) the organolithium source selected or carbon source cost higher, the carbon content of material can not be changed in building-up process neatly;
(2) although too much carbon content can improve the electric transmission of material, the transmission of lithium ion in material can be hindered but then, reduce the volume energy density of material simultaneously.
Therefore, be badly in need of in prior art solving these technical problems, to LiMnPO 4be optimized.
Summary of the invention
For LiMnPO 4the problem of electrochemical kinetics difference, the object of the invention is to provide a kind of heterogeneous nanometer LiMnPO 4/ carbon composite and preparation method thereof.The method can by nanometer LiMnPO 4be dispersed among nano-sized carbon conductive network, effectively improve LiMnPO 4dynamics, improve the chemical property of material.The method of the invention technical process is simple, and the character of energy flexible modulation material, is convenient to the suitability for industrialized production realizing lithium manganese phosphate.
On the one hand, the invention provides a kind of preparation method of heterogeneous nano lithium manganese phosphate of lithium/carbon composite, described method comprises:
(1) surfactant and organic solvent are mixed in the ratio (volume ratio) of 1:10 ~ 1:2, form mixed solution;
(2) Li source compound, manganese source compound and P source compound are joined in the mixed solution of step (1), then add organic carbon source, wherein, carbon accounts for 1 ~ 20% of described composite material quality;
(3) in ball grinder, ball milling is carried out;
(4) by the product after ball milling at 50 ~ 80 DEG C of stirring conditions down to complete evaporate to dryness, then be placed in 300 ~ 400 DEG C of inert atmosphere preliminary treatment 2 ~ 10 hours;
(5) pretreated product is fully ground, at 15 ~ 30atmcm -2(atmospheric pressure/cm 2) suppress under pressure condition, then under inert protective atmosphere, 550 ~ 750 DEG C of temperature lower calcinations 2 ~ 10 hours, obtain heterogeneous nano lithium manganese phosphate of lithium/carbon composite.
In one embodiment of the present invention, surfactant described in step (1) is a kind of or multiple arbitrarily combination be selected from softex kw, hexadecyltrimethylammonium chloride, polyvinylpyrrolidone, PEG400 and oleic acid.
In one embodiment of the present invention, organic solvent described in step (1) is a kind of or multiple arbitrarily combination be selected from ethanol, acetone, ethanol-acetone solution, ethylene glycol and polyethylene glycol.
In one embodiment of the present invention, described Li source compound is be selected from a kind of or multiple arbitrarily combination in lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium phosphate, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
In one embodiment of the present invention, described manganese source compound is a kind of or multiple arbitrarily combination be selected from manganese carbonate, manganese acetate, manganous hydroxide, mangano-manganic oxide and manganese dioxide.
In one embodiment of the present invention, described P source compound is be selected from a kind of or multiple arbitrarily combination in ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphorus pentoxide, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
In one embodiment of the present invention, described organic carbon source is a kind of or multiple arbitrarily combination be selected from glucose, sucrose, citric acid, polyvinyl alcohol 1500, beta-schardinger dextrin-, lactose, polysaccharide.
In one embodiment of the present invention, the mol ratio of described Li source compound, manganese source compound and P source compound is 0.8 ~ 1.2:0.8 ~ 1.2:1.
In one embodiment of the present invention, in step (3), the rotating speed of described ball milling is 200 ~ 800 revs/min (rpm), and Ball-milling Time is 2 ~ 10 hours.
In one embodiment of the present invention, in step (5), described calcining is carried out at 550 ~ 750 DEG C of temperature, and temperature retention time is 1 ~ 10 hour; Wherein, inert protective atmosphere is selected from one or more the combination in nitrogen, argon gas and argon-hydrogen gaseous mixture.
On the other hand, the invention provides the heterogeneous nano lithium manganese phosphate of lithium/carbon composite obtained according to described preparation method;
Wherein, nano lithium manganese phosphate of lithium is dispersed among nano-sized carbon conductive network, and the primary particle average grain diameter of nano lithium manganese phosphate of lithium is 5-15nm, and the particle size range of second particle is at most 50-80nm.
In a preferred embodiment, the primary particle average grain diameter of described nano lithium manganese phosphate of lithium is about 10nm.
Heterogeneous nano lithium manganese phosphate of lithium/carbon composite degree of crystallinity of the present invention is high, and the dislocation of lithium manganese is few, and nano lithium manganese phosphate of lithium is dispersed in the three-dimensional network of conductive carbon formation, improves the chemical property of material to a great extent.Therefore, the high rate performance etc. of this heterogeneous nano lithium manganese phosphate of lithium/carbon composite of the present invention obtains and increases substantially.
In the present invention, " primary particle " refers to crystal grain itself; " second particle " refers to the particle formed after crystal grain is reunited.Usually, the particle diameter of single small grains is called " primary particle size ", also cries " initial size ".When crystal is very tiny time, because the surface energy of crystal grain is very large, easily because weak interaction force combines between tiny crystal grain, cause reuniting between crystal grain, namely a lot of small grains are united, and are formed larger " second particle ".
Specifically, the LiMnPO as anode material for lithium-ion batteries of the present invention 4the preparation method of/C composite comprises the following steps:
(1) surfactant and organic solvent are mixed in the ratio of 1:10 ~ 1:2;
(2) lithium source, manganese source and P source compound are joined step 1 according to certain mol ratio) mixed solution in, add organic carbon source (wherein carbon accounts for target product LiMnPO simultaneously 41 ~ 20 quality % of/C composite);
(3) by step 2) product of gained transfers in ball grinder and carries out ball milling;
(4) by the product after ball milling at 50 ~ 80 DEG C of stirring conditions down to complete evaporate to dryness, then be placed in 300 ~ 400 DEG C of inert atmosphere preliminary treatment 2 ~ 10 hours;
(5) after pre-burning product fully grinds, at 15 ~ 30atmcm -2pressure condition tabletted, under inert gas shielding, 550 ~ 750 DEG C of temperature lower calcinations 2 ~ 10 hours, obtain heterogeneous nanometer LiMnPO 4/ carbon composite.
In the present invention, described surfactant is one or more combinations in softex kw, hexadecyltrimethylammonium chloride, polyvinylpyrrolidone, PEG400 or oleic acid;
In the present invention, described organic solvent is one or more combinations in ethanol, acetone, ethanol-acetone solution, ethylene glycol and polyethylene glycol.
In the present invention, the volume ratio of described surfactant and organic solvent is 1:10 ~ 1:2.
In the present invention, described Li source compound is one or more combinations in lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium phosphate, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
In the present invention, described manganese source compound is one or more combinations in manganese carbonate, manganese acetate, manganous hydroxide, mangano-manganic oxide and manganese dioxide.
In the present invention, described P source compound is one or more combinations in ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphorus pentoxide, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
In the present invention, described organic carbon source is one or more combinations in glucose, sucrose, citric acid, polyvinyl alcohol 1500, beta-schardinger dextrin-, lactose, polysaccharide.
In the present invention, the mol ratio in described lithium source, manganese source and phosphorus source is: 0.8 ~ 1.2:0.8 ~ 1.2:1.
In the present invention, the rotating speed of described mechanical milling process is 200 ~ 600rpm, and Ball-milling Time is 2 ~ 10 hours.
In the present invention, the pretreatment temperature of described material is 300 ~ 400 DEG C, and pretreatment time is 2 ~ 10 hours.
In the present invention, the final calcining heat of described material is 550 ~ 750 DEG C, and temperature retention time is 1 ~ 10 hour, and wherein, described inert atmosphere is nitrogen, argon gas or argon-hydrogen gaseous mixture.
In the present invention, described positive plate manufacturing process is:
(1) by positive electrode (LiMnPO 4/ C composite), acetylene black, polyvinylidene fluoride (PVDF) be dispersed in a certain amount of nmp solvent in the ratio (mass ratio) of 8:1:1;
(2) under 10000rpm rotating speed, half an hour is uniformly mixed with high-speed shearing machine;
(3) after fully mixing, coating machine is coated with, and it is dry to put into 60 DEG C of baking ovens;
(4) dry rear pole piece thickness is 50 ~ 60nm, and pole piece is depressed into 75% of original depth by recycling roll squeezer;
(5) being washed into diameter is after the circular pole piece of 13mm, puts into 120 DEG C of vacuum drying ovens dry 16 hours, then puts into glove box.
In the present invention, the making of described button cell and test process are:
(1) in the glove box being full of argon shield gas, button cell is assembled, wherein, with the LiMnPO of above-mentioned making 4/ C pole piece as positive pole, using lithium sheet as negative pole, 1molL -1liPF 6being dissolved in (volume ratio: 1:1:1) in ethylene carbonate (EC)/methyl ethyl carbonate (EMC)/dimethyl carbonate (DMC) solvent is electrolyte, and Celgard2500 polypropylene screen (purchased from American Celgard company) is barrier film.
(2) in the upper test of Maccor battery charging and discharging tester (purchased from generation Magotan Science and Technology Ltd.):
In formation process, use the current density constant current charge of C/20 to 4.5V, be less than C/50 in this voltage constant voltage to current density, then use the current density constant-current discharge of C/20 to 2.5V, formation process continues three circles.
During loop test, with 0.1C rate charge-discharge 100 times.During multiplying power test, battery, with the charging of 0.1C multiplying power, encloses in 0.1C, 0.2C, 0.5C, 1.0C, 2.0C, 5.0C, 10.0C, 20.0C different multiplying electric discharge 5 respectively.
LiMnPO provided by the invention 4the heterogeneous nano composite material of/C has following advantage:
(1) what adopt is surfactant assisted Solid-state synthetic method, and synthesis technique is simple, and cost is low, easy control of process conditions, can regulate the phosphorus content of material neatly, improves the volume energy density of material;
(2) LiMnPO obtained 4/ C heterogeneous nano composite material degree of crystallinity is high, and lithium manganese inconsistent phenomenon is few, improves the specific capacity of material;
(3), in preparation process, surfactant in-situ carburization generates carbon-coating and covers LiMnPO 4on the surface, effectively inhibit growth and the agglomeration of particle in high-temperature burning process;
(4) pyrolysis of carbon source (such as, sucrose) defines the network configuration of three between particles, improves the ionic conductivity of material;
(5) LiMnPO obtained 4/ C heterogeneous nano composite material primary particle particle diameter is very little, and average grain diameter is about 10nm, shortens the diffusion length of lithium ion in material to a great extent, adds the contact area of material and electrolyte, drastically increases the electrochemical kinetics of material;
(6) LiMnPO obtained 4the heterogeneous nano composite material chemical property of/C is good, and 0.1C capacity is up to 130mAhg -1, circulation 50 circle capability retention is 97.5%, and this is cycle performance best in prior art bibliographical information; With
(7) LiMnPO 4the high magnification capacity of the heterogeneous nano composite material of/C also significantly improves: the discharge capacity of 10C, 20C is respectively 87.1 and 60.1mAhg -1.
Accompanying drawing explanation
Fig. 1 is LiMnPO prepared by the embodiment of the present invention 1 4scanning electron microscopy (SEM) photo of the heterogeneous nano composite material of/C.
Fig. 2 is LiMnPO prepared by the embodiment of the present invention 1 4high resolution transmission electron microscopy (HRTEM) figure of the heterogeneous nano composite material of/C.
Fig. 3 is LiMnPO prepared by the embodiment of the present invention 1 4the heterogeneous nano composite material of/C changes into the voltage-capacity curve chart of three circles under 0.05C.
Fig. 4 is LiMnPO prepared by the embodiment of the present invention 1 4the discharge capacity figure of the heterogeneous nano composite material of/C under different multiplying.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, and to make those skilled in the art the present invention may be better understood and can be implemented, but illustrated embodiment is not as a limitation of the invention.
Embodiment 1
By surfactant polyvinylpyrrolidone (PVP) and organic solvent-acetone by volume 1:2 mix, form uniform mixed solution.
Take lithium acetate that mol ratio is 1.05:1:1.05, manganese acetate, ammonium dihydrogen phosphate join in above-mentioned mixed solution respectively as lithium source, manganese source and phosphorus source, account for target product 15wt% by carbon simultaneously and take organic carbon source sucrose and join together in mixed solution.
Transfer in ball grinder by gained mixed solution, 400rpm speed conditions ball milling 10 hours, then transfer in beaker by ball milling product, at 60 DEG C, be stirred to drying with magneton, putting into tube furnace at hydrogen quality mark was the Ar/H of 8wt% 2pre-burning 5 hours under 400 DEG C of conditions in protection gas.
Pre-burning product is ground to fine uniform powder, at 15atmcm in mortar -2condition is pressed into sheet, then puts into tube furnace, at Ar/H 2in protection gas, 700 DEG C of conditions sinter 5 hours, are then cooled to normal temperature.In mortar, grind to form fine uniform powder, obtain hierarchy LiMnPO 4/ C superfine nano composite material.
According to method of testing of the present invention to embodiment 1 gained LiMnPO 4/ C superfine nano composite material is tested:
(1) 0.1C capacity is up to 130mAhg -1, circulation 50 circle capability retention is 97.5%; With
(2) discharge capacity of 10C, 20C is respectively 87.1 and 60.1mAhg -1.
LiMnPO prepared by embodiment 1 4scanning electron microscopy (SEM) photo, high resolution transmission electron microscopy (HRTEM) figure of the heterogeneous nano composite material of/C, under 0.05C, change into the voltage-capacity curve chart of three circles and the discharge capacity figure under different multiplying is shown in Fig. 1,2,3 and 4 respectively.
Embodiment 2
By surfactant oleic acid and organic solvent ethanol by volume 2:5 mix, form uniform mixed solution.
Take lithium hydroxide that mol ratio is 1.1:1:1.05, manganese carbonate, ammonium dihydrogen phosphate join in above-mentioned mixed solution respectively as lithium source, manganese source and phosphorus source, account for target product 10wt% by carbon simultaneously and take organic carbon source sucrose and join together in mixed solution.
Transfer in ball grinder by gained mixed solution, 600rpm speed conditions ball milling 5 hours, then transfer in beaker by ball milling product, at 60 DEG C, be stirred to drying with magneton, putting into tube furnace at hydrogen quality mark was the Ar/H of 8wt% 2350 DEG C of condition pre-burnings 5 hours in protection gas.
Pre-burning product is ground to fine uniform powder, at 20atmcm in mortar -2condition is pressed into sheet, then puts into tube furnace, at Ar/H 2in protection gas, 750 DEG C of conditions sinter 10 hours, are then cooled to normal temperature.In mortar, grind to form fine uniform powder, obtain hierarchy LiMnPO 4/ C superfine nano composite material.
According to method of testing of the present invention to embodiment 2 gained LiMnPO 4/ C superfine nano composite material is tested:
(1) 0.1C capacity is up to 135mAhg -1, circulation 50 circle capability retention is 97.9%; With
(2) discharge capacity of 10C, 20C is respectively 89.1 and 65.1mAhg -1.
Through test, applicant finds LiMnPO prepared by embodiment 2 4scanning electron microscopy (SEM) photo and high resolution transmission electron microscopy (HRTEM) figure and Fig. 1 and 2 of the heterogeneous nano composite material of/C are similar; The similar nature that the voltage-capacity curve of three circles and the discharge capacity under different multiplying and Fig. 3 and 4 show is changed under 0.05C.
Embodiment 3
By surfactant PVP and organic solvent ethanol-acetone by volume 1:5 mix, form uniform mixed solution.
Take lithium carbonate that mol ratio is 0.5:1:1.05, manganese carbonate, diammonium hydrogen phosphate join in above-mentioned mixed solution respectively as lithium source, manganese source and phosphorus source, account for target product 20wt% by carbon simultaneously and take organic carbon source sucrose and join together in mixed solution.
Transfer in ball grinder by gained mixed solution, 400rpm speed conditions ball milling 6 hours, then transfer in beaker by ball milling product, at 60 DEG C, be stirred to drying with magneton, putting into tube furnace at hydrogen quality mark was the Ar/H of 8wt% 2400 DEG C of condition pre-burnings 5 hours in protection gas.
Pre-burning product is ground to fine uniform powder, at 25atmcm in mortar -2condition is pressed into sheet, then puts into tube furnace, at Ar/H 2in protection gas, 600 DEG C of conditions sinter 5 hours, are then cooled to normal temperature.In mortar, grind to form fine uniform powder, obtain hierarchy LiMnPO 4/ C superfine nano composite material.
According to method of testing of the present invention to embodiment 3 gained LiMnPO 4/ C superfine nano composite material is tested:
(1) 0.1C capacity is up to 131mAhg -1, circulation 50 circle capability retention is 97.7%; With
(2) discharge capacity of 10C, 20C is respectively 87.5 and 63.2mAhg -1.
Through test, applicant finds LiMnPO prepared by embodiment 3 4scanning electron microscopy (SEM) photo and high resolution transmission electron microscopy (HRTEM) figure and Fig. 1 and 2 of the heterogeneous nano composite material of/C are similar; The similar nature that the voltage-capacity curve of three circles and the discharge capacity under different multiplying and Fig. 3 and 4 show is changed under 0.05C.
Embodiment 4
By surfactant softex kw (CTAB) and organic solvent ethylene glycol by volume 1:3 mix, form uniform mixed solution.
Take lithium oxalate that mol ratio is 0.5:1:1.05, manganous hydroxide, diammonium hydrogen phosphate join in above-mentioned mixed solution respectively as lithium source, manganese source and phosphorus source, account for target product 12wt% by carbon simultaneously and take organic carbon source sucrose and join together in mixed solution.
Transfer in ball grinder by gained mixed solution, 500rpm speed conditions ball milling 8 hours, then transfer in beaker by ball milling product, at 70 DEG C, be stirred to drying with magneton, putting into tube furnace at hydrogen quality mark was the Ar/H of 8wt% 2pre-burning 10 hours under 350 DEG C of conditions in protection gas.
Pre-burning product is ground to fine uniform powder, at 25atmcm in mortar -2condition is pressed into sheet, then puts into tube furnace, at Ar/H 2in protection gas, 700 DEG C of conditions sinter 10 hours, are then cooled to normal temperature.In mortar, grind to form fine uniform powder, obtain hierarchy LiMnPO 4/ C superfine nano composite material.
According to method of testing of the present invention to embodiment 4 gained LiMnPO 4/ C superfine nano composite material is tested:
(1) 0.1C capacity is up to 132.6mAhg -1, circulation 50 circle capability retention is 97.2%; With
(2) discharge capacity of 10C, 20C is respectively 88.7 and 66.5mAhg -1.
Through test, applicant finds LiMnPO prepared by embodiment 4 4scanning electron microscopy (SEM) photo and high resolution transmission electron microscopy (HRTEM) figure and Fig. 1 and 2 of the heterogeneous nano composite material of/C are similar; The similar nature that the voltage-capacity curve of three circles and the discharge capacity under different multiplying and Fig. 3 and 4 show is changed under 0.05C.
Embodiment 5
By surfactant polyethylene 400 and organic solvent-acetone by volume 1:2 mix, form uniform mixed solution.
Take lithium carbonate that mol ratio is 0.6:1:1.05, manganese dioxide, ammonium phosphate joins in above-mentioned mixed solution respectively as lithium source, manganese source and phosphorus source, account for target product 18wt% by carbon simultaneously and take organic carbon source sucrose and join together in mixed solution.
Transfer in ball grinder by gained mixed solution, 400rpm speed conditions ball milling 10 hours, then transfer in beaker by ball milling product, at 80 DEG C, be stirred to drying with magneton, putting into tube furnace at hydrogen quality mark was the Ar/H of 8wt% 2pre-burning 8 hours under 350 DEG C of conditions in protection gas.
Pre-burning product is ground to fine uniform powder, at 30atmcm in mortar -2condition is pressed into sheet, then puts into tube furnace, at Ar/H 2in protection gas, 750 DEG C of conditions sinter 8 hours, are then cooled to normal temperature.In mortar, grind to form fine uniform powder, obtain hierarchy LiMnPO 4/ C superfine nano composite material.
According to method of testing of the present invention to embodiment 5 gained LiMnPO 4/ C superfine nano composite material is tested:
(1) 0.1C capacity is up to 132.5mAhg -1, circulation 50 circle capability retention is 97.6%; With
(2) discharge capacity of 10C, 20C is respectively 87.5 and 65.9mAhg -1.
Through test, applicant finds LiMnPO prepared by embodiment 5 4scanning electron microscopy (SEM) photo and high resolution transmission electron microscopy (HRTEM) figure and Fig. 1 and 2 of the heterogeneous nano composite material of/C are similar; The similar nature that the voltage-capacity curve of three circles and the discharge capacity under different multiplying and Fig. 3 and 4 show is changed under 0.05C.
Be the LiMnPO of preparation see Fig. 1: Fig. 1 4the SEM image of the heterogeneous nano composite material of/C.Wherein, LiMnPO 4particle size range is 50 ~ 80nm, does not have obvious agglomeration, adds and effectively can suppress growing up and reuniting of particle while showing carbon source and surfactant.Described in principle, the existence of polyvinylpyrrolidone (PVP) micella is by LiMnPO 4growth be limited in a nano level space, when polyvinylpyrrolidone (PVP) major part volatilization after, RESEARCH OF PYROCARBON is distributed in the lower LiMnPO of degree of crystallinity 4, inhibit the reunion of particle in high-temperature burning process around, make the material particle size of synthesis little, be evenly distributed.
The LiMnPO of preparation see Fig. 2: Fig. 2 4high resolution transmission electron microscopy (HRTEM) figure of the heterogeneous nano composite material of/C.Which show the internal structure of individual particle in Fig. 1, wherein can clearly be seen that in Fig. 1, the particle of 50 ~ 80nm is second particle, primarily of being distributed in the primary particle composition that particle diameter in carbon network is 8 ~ 10nm, in figure, width is 1.74 Hes lattice fringe correspond to LiMnPO 4(123) and (112) face.These nano particles are that growth is formed from the nanometer scale space of polyvinylpyrrolidone (PVP) micella, carbon coating layer is around that polyvinylpyrrolidone (PVP) pyrolysis of staying presoma surface obtains, and inhibits growing up in material at high temperature calcination process well.Due to the original position pyrolysis carbonization of polyvinylpyrrolidone (PVP), define uniform close ground compound between primary particle and conductive carbon, improve the transmission rate of electronics in material.

Claims (11)

1. a preparation method for heterogeneous nano lithium manganese phosphate of lithium/carbon composite, is characterized in that, described method comprises:
(1) surfactant and organic solvent are pressed the volume ratio mixing of 1:10 ~ 1:2, form mixed solution;
(2) Li source compound, manganese source compound and P source compound are joined in the mixed solution of step (1), then add organic carbon source, wherein, carbon accounts for 1 ~ 20% of described composite material quality;
(3) in ball grinder, ball milling is carried out;
(4) by the product after ball milling at 50 ~ 80 DEG C of stirring conditions down to complete evaporate to dryness, then be placed in 300 ~ 400 DEG C of inert atmosphere preliminary treatment 2 ~ 10 hours;
(5) pretreated product is fully ground, at 15 ~ 30atmcm -2suppress under pressure condition, then under inert protective atmosphere, 550 ~ 750 DEG C of temperature lower calcinations 2 ~ 10 hours, obtain heterogeneous nano lithium manganese phosphate of lithium/carbon composite.
2. preparation method according to claim 1, it is characterized in that, in step (1), described surfactant is a kind of or multiple arbitrarily combination be selected from softex kw, hexadecyltrimethylammonium chloride, polyvinylpyrrolidone, PEG400 and oleic acid.
3. preparation method according to claim 1, is characterized in that, in step (1), described organic solvent is a kind of or multiple arbitrarily combination be selected from ethanol, acetone, ethanol-acetone solution, ethylene glycol and polyethylene glycol.
4. preparation method according to claim 1, is characterized in that, described Li source compound is be selected from a kind of or multiple arbitrarily combination in lithium carbonate, lithium hydroxide, lithium acetate, lithium oxalate, lithium phosphate, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
5. preparation method according to claim 1, is characterized in that, described manganese source compound is a kind of or multiple arbitrarily combination be selected from manganese carbonate, manganese acetate, manganous hydroxide, mangano-manganic oxide and manganese dioxide.
6. preparation method according to claim 1, is characterized in that, described P source compound is be selected from a kind of or multiple arbitrarily combination in ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphorus pentoxide, lithium dihydrogen phosphate and phosphoric acid hydrogen two lithium.
7. preparation method according to claim 1, is characterized in that, described organic carbon source is a kind of or multiple arbitrarily combination be selected from glucose, sucrose, citric acid, polyvinyl alcohol 1500, beta-schardinger dextrin-, lactose, polysaccharide.
8. preparation method according to claim 1, is characterized in that, the mol ratio of described Li source compound, manganese source compound and P source compound is 0.8 ~ 1.2:0.8 ~ 1.2:1.
9. preparation method according to claim 1, is characterized in that, in step (3), the rotating speed of described ball milling is 200 ~ 800rpm, and Ball-milling Time is 2 ~ 10 hours.
10. preparation method according to claim 1, is characterized in that, in step (5), described calcining is carried out at 550 ~ 750 DEG C of temperature, and temperature retention time is 1 ~ 10 hour; Wherein, inert protective atmosphere is selected from one or more the combination in nitrogen, argon gas and argon-hydrogen gaseous mixture.
The 11. heterogeneous nano lithium manganese phosphate of lithium/carbon composites obtained according to preparation method described in any one of claim 1-10; Wherein, nano lithium manganese phosphate of lithium is dispersed among nano-sized carbon conductive network, and the primary particle average grain diameter of nano lithium manganese phosphate of lithium is 5-15nm, and the particle size range of second particle is at most 50-80nm.
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Cited By (3)

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Publication number Priority date Publication date Assignee Title
CN105977456A (en) * 2015-03-12 2016-09-28 中国科学院成都有机化学有限公司 Solid-phase synthesis method for preparing LiMn1-xFexPO4/C composite material
CN107093726A (en) * 2017-05-02 2017-08-25 安庆师范大学 A kind of method for improving lithium ion battery electrode material chemical property
CN109411715A (en) * 2018-09-14 2019-03-01 华南理工大学 A kind of high-performance lithium iron manganese phosphate anode material and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LONGFEI ZHANG等: "Confined synthesis of hierarchical structured LiMnPO4/C granules by a facile surfactant-assisted solid-state method for high-performance lithiumion batteries", 《J. MATER. CHEM. A》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105977456A (en) * 2015-03-12 2016-09-28 中国科学院成都有机化学有限公司 Solid-phase synthesis method for preparing LiMn1-xFexPO4/C composite material
CN107093726A (en) * 2017-05-02 2017-08-25 安庆师范大学 A kind of method for improving lithium ion battery electrode material chemical property
CN109411715A (en) * 2018-09-14 2019-03-01 华南理工大学 A kind of high-performance lithium iron manganese phosphate anode material and preparation method thereof

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