CN103427079A - Preparation method of lithium ion phosphate/carbon composite material for high-rate-capability lithium ion battery - Google Patents
Preparation method of lithium ion phosphate/carbon composite material for high-rate-capability lithium ion battery Download PDFInfo
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Abstract
The invention discloses a preparation method of a lithium ion phosphate/carbon composite material for a high-rate-capability lithium ion battery. The preparation method comprises the following steps: analyzing the iron content and the phosphorus content of a precursor ferrous phosphate powder; adding into mixed slurry of a lithium source, a ferrous phosphate precursor and a phosphorus source according to the molar ratio of Li:Fe:P=(1.02-1):(0.98-1):1, adding a proper amount of a liquid phase reducing agent and a conductive additive, performing reflux reaction at the boiling point temperature of the reducing agent, distilling under reduced pressure and recovering a reducing solvent to obtain a lithium ion phosphate precursor; and calcining under the protection of inert gas to obtain a LiFePO4/C composite anode material. Compared with other methods, the preparation method has the advantages of simple flow, short reaction time, simple process equipment, fine synthesis product particles, uniform particle size distribution, good high-rate electrochemical performance and excellent circulating stability, and besides, the discharging specific capacity is up to 100 mAh/g at 10 C,. The synthesis reaction process does not need a high-pressure container and only needs short high-temperature calcining time, so the reducing solvent is easy to recover, energy consumption is greatly reduced; the industrial popularization is facilitated.
Description
Technical field
The present invention relates to high multiplying power lithium ion battery positive electrode preparation field, particularly a kind of preparation method of the high magnification characteristic lithium iron phosphate/carbon anode composite based on the polyhydroxyl solvents wet heating.
Background technology
The world today, petroleum resources are day by day nervous, and environmental pollution is on the rise, and people more and more pay attention to take the secondary energy sources that green secondary cell is power.The great demand in the fields such as defence and military, Aero-Space, electric tool, motor vehicle, electronic information and instrument and meter, make and take the power type green energy-storing device of new generation that lithium-ion-power cell is representative and become the focus that global high-tech industry field is paid close attention to.
Positive electrode has conclusive effect to the performance of lithium ion battery always.For lithium-ion-power cell, what research was concentrated the most at present is the nickle cobalt lithium manganate system (LiNixCoyMn1-x-yO2) of ternary, LiMn2O4 (LiMn2O4) with spinel structure, have the LiFePO4 (LiFePO4) of olivine structural.Wherein the LiFePO4 of rhombic system olivine-type is cheap owing to having, and fail safe is good, has extended cycle life, and environmentally safe and become a kind of most potential lithium-ion-power cell material, caused the broad interest of academia and industrial circle.But its practical application that LiFePO4 has existed electronic conductivity and the low drawbacks limit of ion diffusion rate, adopt different preparation technologies to improve its shortcoming at present, on the whole, mainly comprise the methods such as carbon coats, metal-doped, grain size control.
It is source of iron that invention CN101339991 be take the mixture of organic and inorganic ferric iron compound, mix lithium source and P source compound, LiFePO4/ (C+Fe2P) composite material that utilizes carbothermic method to make to be formed by carbon, Fe2P and LiFePO4, the synthetic material of this method has good chemical property, but still exist particle thicker, and the problems such as size is inhomogeneous, high rate capability has much room for improvement, and the technical process energy consumption is high.
Patent CN101559935 adopts coprecipitation to prepare particle diameter controlled spherical ferric phosphate and lithium phosphate, then use the solid sintering technology synthesizing iron lithium phosphate, the technical process that wet-precipitated-prepared by the high temperature sintering method is longer, the controlled condition harshness, batches of materials stability is bad, and cost is higher equally.
Invention CN101475157, CN101007630 discloses the method for hydro thermal method for the preparation of lithium ion secondary battery anode material ferric lithium phosphate.By the lithium source, source of iron and source of phosphoric acid mix and are made into the certain density aqueous solution, and add appropriate reducing agent, carbon forming agent, ionic dopants etc., make the grain growth slaking under the water under high pressure heat condition, after hydrothermal product is removed solvent, under inertia or reducing atmosphere, calcination gets final product to obtain end product, and the hydro thermal method synthetic material need be under high pressure carrying out, high to equipment requirement.
By patent retrieval, find that a kind of polyhydroxyl solvents wet heating prepares the method for LiFePO4 (CN101973540A), prepare LiFePO4 with a certain amount of ethylene glycol Substitute For Partial pure water solvent in autoclave, its essence is to utilize boiling point to increase reaction temperature and pressure higher than the solvent of water, with hydro thermal method, there is no essential distinction.
The scholars such as Korea S D.H.Kim had once published one piece of method of utilizing the polyhydroxyl solvents normal pressure to prepare LiFePO4 (D.H.Kim, J.Kim, Electrochem.Sol.State Lett., 2006,9(9) A439-A442), this method adopts the expensive raw materials such as ferrous acetate, lithium acetate, and in the tetraethylene glycol solvent, back flow reaction obtains physical and chemical performance LiFePO4 preferably in 16 hours.
After this, this seminar prepares aspect LiFePO4 and has done a series of activities at the polyhydroxyl solvents normal pressure: as utilize above-mentioned raw materials, boiling temperature reaction 16h at different polyhydroxyl solvents prepares LiFePO4 respectively, its chemical property improves (D.H.Kim, J.S.Im along with the rising of boiling temperature
.Et al., J.NANOSCI.NANOTECHNO., 2007 .V73949-3953); And for example under same reaction conditions, regulating the addition that conductive acetylene is black finds the impact of lithium iron phosphate positive material performance, best (the E.S.Choi of the performance of LiFePO4 when addition is 5%, D.H.Kim et al., J.NANOSCI.NANOTECHNO.2010, Vol.10,3416 – 3419).
Scholar Sinha(N.N.Sinha, N.M., J.ELECTROCHEM.SO., 2010,157(7) A824-A829) utilize FePO
42H
2Under O presoma, tetraethylene glycol boiling point, reaction 13h normal pressure prepares LiFePO4, and its high rate capability has no report.
Therefore, need a kind ofly under mild process condition and low power technology flow process, prepare that powder diameter is little, particle diameter is evenly distributed, the olivine structure lithium iron phosphate of high rate capability excellence/carbon clad anode material.
Summary of the invention
The object of the present invention is to provide the preparation method of a kind of high rate capability lithium ion battery by lithium iron phosphate/carbon composite material, can be under mild process condition and low power technology flow process, prepare that powder diameter is little, particle diameter is evenly distributed, the olivine structure lithium iron phosphate of high rate capability excellence/carbon clad anode material, technique is simple, preparation time is short, efficiency is high, and saves Financial cost.
The preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery of the present invention is characterized in that: comprise the following steps:
A. prepare ferric lithium phosphate precursor: allocate the ferrous phosphate powder into He Lin source, lithium source and conductive additive according to the ratio of Li:Fe:P=1.02-1:0.98-1:1, then add the liquid-phase reduction agent and be heated to the boiling temperature atmospheric pressure reflux of reducing agent solvent, finally reducing agent is separated from liquid-phase system, made ferric lithium phosphate precursor;
B. the ferric lithium phosphate precursor in step b is calcined under inert gas shielding to the composite material that obtains lithium iron phosphate/carbon;
Further, in step a, the mol ratio of the described LiFePO4 that adds the liquid-phase reduction solvent and make is 8-12:1, and at atmospheric pressure reflux 4-10 hour; The addition of described conductive agent is the 5%-30% that wish prepares the LiFePO4 quality;
Further, in step a, described liquid-phase reduction solvent is 10:1 with the mol ratio of the LiFePO4 made; The addition of described conductive agent be wish prepare the LiFePO4 quality 15%;
The particle size D of the ferrous phosphate powder further, made in step a
50Between 1-5 μ m;
Further, in step a, described lithium source is one or more mixtures in lithium hydroxide, lithium carbonate, lithium oxalate, lithium acetate and lithium nitrate; Described liquid-phase reduction solvent is one or more mixtures in ethylene glycol, diethylene glycol (DEG), triethylene glycol, tetraethylene glycol, methyl-sulfoxide, glycerol; Described conductive additive is one or both in citric acid, ascorbic acid, one or more mixtures of the inorganic conductive agent such as perhaps one or more mixtures in glucose, sucrose, fructose, or acetylene black, carbon nano-tube, electrically conductive graphite.
Further, in step b, 550-750 ℃ of calcining 1-5h under the ferric lithium phosphate precursor inert gas shielding obtained to the composite material of lithium iron phosphate/carbon;
Further, in step b, the lower 650 ℃ of calcining 1h of ferric lithium phosphate precursor inert gas shielding are obtained to the composite material of lithium iron phosphate/carbon.
Beneficial effect of the present invention: the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery of the present invention, adopt ferrous phosphate as presoma, utilizing the liquid-phase reduction agent to serve as reducing agent is reduced to a small amount of ferric iron in ferrous phosphate divalence and guarantees that ferrous iron can be not oxidized in reaction, bring into play the sterically hindered effect of liquid-phase reduction agent simultaneously, the LiFePO 4 nucleus is wrapped in the hydroxyl of a large amount of existence, suppresses growing up of particle.Streamlining of the present invention, the reaction time is short, process equipment is simple, and the synthetic product particle is tiny, and particle diameter is evenly distributed, and has good high magnification chemical property and excellent stable circulation performance.Without high-pressure bottle, only need the shorter high-temperature calcination time due to synthetic reaction process, the advantages such as the easy recovery of reduction solvent, energy consumption significantly reduces, and is easy to industry and promotes.The lithium iron phosphate/carbon composite material with high rate capability that will make according to the method is for lithium ion battery, 0.1C first discharge specific capacity is greater than 150mAh/g, the 1C first discharge specific capacity is greater than 140mAh/g, under room temperature, the 10C first discharge specific capacity is greater than 110mAh/g, and the capability retention after 500 times that circulates is 88%.
The accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments to further instruction of the present invention.
The SEM figure of the lithium ion anode material ferrous phosphate powder that Fig. 1 is embodiment 1 preparation;
The SEM figure of the lithium ion anode material lithium iron phosphate/carbon composite material that Fig. 2 is embodiment 1 preparation;
The XRD figure of the lithium ion anode material LiFePO4 that Fig. 3 is embodiment 1 preparation;
First charge-discharge curve chart under each multiplying power of lithium ion anode material lithium iron phosphate/carbon composite material that Fig. 4 is embodiment 1 preparation;
Electrochemistry cycle performance figure under the different discharge-rates of the lithium ion anode material lithium iron phosphate/carbon composite material that Fig. 5 is embodiment 1 preparation;
Embodiment
The preparation method of lithium iron phosphate/carbon composite material for the high rate capability lithium ion battery of the present embodiment is characterized in that: comprise the following steps:
A. prepare ferric lithium phosphate precursor: allocate the ferrous phosphate powder into He Lin source, lithium source and conductive additive according to the ratio of Li:Fe:P=1.02-1:0.98-1:1, then add the liquid-phase reduction agent and be heated to the boiling temperature atmospheric pressure reflux of reducing agent solvent, finally reducing agent is separated from liquid-phase system to (as reducing agent is reclaimed in decompression distillation), made ferric lithium phosphate precursor; Course of reaction makes without high-temperature calcination and inert gas shielding the lithium iron phosphate positive material that surface coats one deck conductive agent.
Conductive additive can effectively improve the migration rate of lithium ion in electrode material, thereby improves the high rate performance of battery;
The ferrous phosphate powder buyable adopted also can adopt following method self-control:
Ferrous salt solution with inorganic acid for adjusting pH to 2 is evenly mixed with phosphate solution, under certain reaction temperature, adding alkali lye regulation system pH value to obtain the ferrous phosphate precipitation to 5.4-7, rapid stirring reaction 1-15min, after reaction, filtration washing is precipitated to without SO
4 2-, after atmospheric pressure at room is air-dry, standby by waiting until after ferrous phosphate powdery analysis iron, phosphorus content;
Wherein, described inorganic acid is at least one in sulfuric acid, nitric acid or hydrochloric acid; Described ferrous salt is at least one in ferrous sulfate, frerrous chloride, ferrous acetate, ferrous oxalate, ferrous nitrate; Described phosphate is at least one in ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, organic phosphorus sources; Alkali lye is sodium hydrate aqueous solution or ammonia spirit;
Wherein, the mol ratio of the iron ion in ferrous salt and described phosphate anion is 3:2; The concentration of the aqueous solution of described ferrous salt is 0.1mol/L-2mol/L, preferably 2mol/L; Described aqueous phosphatic concentration is 0.1mol/L-2mol/L, preferably 2mol/L; Described concentration of lye is 0.1-1mol/L, is preferably 0.5mol/L; In reactions steps, temperature is 5-25 ℃, preferably 10 ℃.
B. the ferric lithium phosphate precursor in step b is calcined under inert gas shielding to the composite material that obtains lithium iron phosphate/carbon; Described inert gas is selected from least one in nitrogen or argon gas.
In the present embodiment, in step a, the mol ratio of the described LiFePO4 that adds the liquid-phase reduction solvent and make is 8-12:1, and at atmospheric pressure reflux 4-10 hour; The addition of described conductive agent is the 5%-30% that wish prepares the LiFePO4 quality.
In the present embodiment, in step a, described liquid-phase reduction solvent is 10:1 with the mol ratio of the LiFePO4 made; The addition of described conductive agent be wish prepare the LiFePO4 quality 15%.
In the present embodiment, the particle size D of the ferrous phosphate powder made in step a
50Between 1-5 μ m.
In the present embodiment, in step a, described lithium source is at least one in lithium hydroxide, lithium carbonate, lithium oxalate, lithium acetate and lithium nitrate; Described liquid-phase reduction solvent is one or more mixtures in ethylene glycol, diethylene glycol (DEG), triethylene glycol, tetraethylene glycol, methyl-sulfoxide, glycerol; Described conductive additive is one or both in citric acid, ascorbic acid, one or more mixtures of the inorganic conductive agent such as perhaps one or more mixtures in glucose, sucrose, fructose, or acetylene black, carbon nano-tube, electrically conductive graphite.
In the present embodiment, in step b, 550-750 ℃ of calcining 1-5h under the ferric lithium phosphate precursor inert gas shielding obtained to the composite material of lithium iron phosphate/carbon.
In the present embodiment, in step b, the lower 650 ℃ of calcining 1h of ferric lithium phosphate precursor inert gas shielding are obtained to the composite material of lithium iron phosphate/carbon.
Embodiment mono-
The copperas solution that will be 1) 2mol/L by sulphur acid for adjusting pH value to 2, molar concentration is that 3:2 reacts with 2mol/L ammonium dihydrogen phosphate liquid by stoichiometric proportion, regulates pH value to 6.0 and obtains the ferrous phosphate precipitation, and the fast filtering washing is extremely without SO
4 2-, by wet cake be placed in air at room temperature air-dry after, survey iron, phosphorus content is waited until standby.
2) by 1) the ferrous phosphate powder that obtains is by lithium: iron: the stoichiometric proportion=1.00:0.98:1 of phosphorus adds ,Lin source, lithium source and conductive additive, then adds the liquid-phase reduction agent; The quality of conductive additive is 15% of the LiFePO4 quality that makes, and the liquid-phase reduction solvent is 10:1 with the mol ratio of the LiFePO4 made; Be transferred in three-necked bottle, with regulating temp. electrothermal cover heating, 100 ℃ water is evaporated after, then, in liquid-phase reduction agent solvent boiling point temperature atmospheric pressure reflux 6 hours, then slurry is moved to cucurbit mesolow distillation liquid phase reducing agent; Course of reaction makes without high-temperature calcination and inert gas shielding the lithium iron phosphate positive material that surface coats one deck conductive agent.
3) by step 2) in the LiFePO4 inert nitrogen gas protect lower 650 ℃ of calcining 1h to obtain the composite material of lithium iron phosphate/carbon.
In the present embodiment, the particle size D of ferrous phosphate powder
50Between 1-5 μ m.
Lithium source in the present embodiment is lithium hydroxide solution, can adopt one or more mixtures in lithium carbonate, lithium oxalate, lithium acetate and lithium nitrate to replace lithium hydroxide solution, phosphorus source in the present embodiment is phosphoric acid, also can adopt one or more mixing phosphorus sources in the organic phosphorus sources that contains P elements; Conductive additive in the present embodiment is citric acid, and one or more that also can adopt acetylene black in one or more or the inorganic conductive agent in similar other organic acids (as ascorbic acid) of physics and chemistry character or the glucose in the machine carbohydrate, sucrose, fructose, carbon nano-tube, electrically conductive graphite replace citric acids; Liquid-phase reduction agent in the present embodiment is triethylene glycol, also exploits one or more mixtures in spent glycol, diethylene glycol (DEG), tetraethylene glycol, methyl-sulfoxide, glycerol and replaces triethylene glycol, and after above-mentioned substance is replaced, composite material character is without significant difference.
The stereoscan photograph of the ferrous phosphate as anode material of lithium ion battery presoma that this embodiment makes as shown in Figure 1, the average grain diameter of known this lamella ferrous phosphate presoma is 1-4 μ m left and right, SEM Fig. 2 of gained lithium iron phosphate/carbon composite material and XRD Fig. 3 can find out that the average grain diameter of corynebacterium LiFePO4 product is 100-200nm thus, for olivine-type orthohormbic structure, perfect crystalline.
The first charge-discharge curve of the experimental cell of being made by the lithium ion electromagnetism positive electrode of embodiment 1 is shown in Fig. 3, and its 0.1C first discharge specific capacity is 150mAh/g as seen, and the 1C first discharge specific capacity is 143mAh/g, and the 10C first discharge specific capacity is 116mAh/g.
Embodiment bis-
The copperas solution that will be 1) 1.5mol/L by sulphur acid for adjusting pH value to 2, molar concentration is that 3:2 reacts with 1.5mol/L ammonium dihydrogen phosphate liquid by stoichiometric proportion, regulates pH value to 5.8 and obtains the ferrous phosphate precipitation, and the fast filtering washing is extremely without SO
4 2-, by wet cake be placed in air at room temperature air-dry after, survey iron, phosphorus content is waited until standby.
2) by 1) the ferrous phosphate powder that obtains is by lithium: iron: the stoichiometric proportion=1.01:0.99:1 of phosphorus adds ,Lin source, lithium source and conductive additive, then to add liquid-phase reduction agent, the quality of conductive additive be 5% of the LiFePO4 quality that makes; The liquid-phase reduction solvent is 8:1 with the mol ratio of the LiFePO4 made; Be transferred in three-necked bottle; with regulating temp. electrothermal cover, heat; 100 ℃ water is evaporated after; again in liquid-phase reduction agent boiling point atmospheric pressure reflux 8 hours; then slurry is moved to cucurbit mesolow distillation liquid phase reducing agent, course of reaction makes without high-temperature calcination and inert gas shielding the lithium iron phosphate positive material that surface coats one deck conductive agent.
3) by step 2) in LiFePO4 inert gas argon gas protect lower 550 ℃ of calcining 2h to obtain the composite material of lithium iron phosphate/carbon.
In the present embodiment, the particle size D of ferrous phosphate powder
50Between 1-5 μ m.
Lithium source in the present embodiment is lithium oxalate solution, can adopt one or more mixtures in lithium hydroxide, lithium acetate and lithium nitrate to replace lithium oxalate solution, phosphorus source in the present embodiment is phosphoric acid, and acid also can adopt one or more mixing phosphorus sources in the organic phosphorus sources that contains P elements; Conductive additive in the present embodiment is citric acid, and one or more that also can adopt acetylene black in one or more or the inorganic conductive agent in similar other organic acids (as ascorbic acid) of physics and chemistry character or the glucose in the machine carbohydrate, sucrose, fructose, carbon nano-tube, electrically conductive graphite replace citric acids; Liquid-phase reduction agent in the present embodiment is diethylene glycol (DEG), also can adopt ethylene glycol, triethylene glycol,, one or more mixtures replace diethylene glycol (DEG)s in tetraethylene glycol, methyl-sulfoxide, glycerol; After above-mentioned substance is replaced, composite material character is without significant difference.
The surface sweeping electromicroscopic photograph that this embodiment prepares gained ferrous phosphate presoma as shown in Figure 1, X-ray diffractogram, stereoscan photograph, specific discharge capacity charging and discharging curve and the cyclic curve figure of the lithium iron phosphate/carbon composite material obtained therefrom and Fig. 2-Fig. 4, without essential distinction, repeat no more herein.0.1C first discharge specific capacity is 152mAh/g, the 1C first discharge specific capacity is 142mAh/g, and the 10C first discharge specific capacity is 112mAh/g.
Embodiment tri-
The copperas solution that will be 1) 1mol/L by sulphur acid for adjusting pH value to 2, molar concentration is that 3:2 reacts with 1mol/L ammonium dihydrogen phosphate liquid by stoichiometric proportion, regulates pH value to 5.6 and obtains the ferrous phosphate precipitation, and the fast filtering washing is extremely without SO
4 2-, by wet cake be placed in air at room temperature air-dry after, survey iron, phosphorus content is waited until standby.
2) by 1) the ferrous phosphate powder that obtains is by lithium: iron: the stoichiometric proportion=1.02:1.00:1 of phosphorus adds ,Lin source, lithium source and conductive additive; The quality of conductive additive is 30% of the LiFePO4 quality that makes, and the liquid-phase reduction solvent is 12:1 with the mol ratio of the LiFePO4 made; Be transferred in three-necked bottle; with regulating temp. electrothermal cover, heat; 100 ℃ water is evaporated after; atmospheric pressure reflux 10 hours under liquid-phase reduction agent solvent boiling point again; then slurry is moved to cucurbit mesolow distillation liquid phase reducing agent, course of reaction makes without high-temperature calcination and inert gas shielding the lithium iron phosphate positive material that surface coats one deck conductive agent.
3) by step 2) in the LiFePO4 inert nitrogen gas protect lower 700 ℃ of calcining 2h to obtain the composite material of lithium iron phosphate/carbon.
In the present embodiment, the particle size D of ferrous phosphate powder
50Between 1-5 μ m.
Lithium source in the present embodiment is lithium oxalate solution solution, can adopt one or more mixtures in lithium hydroxide, lithium carbonate, lithium acetate and lithium nitrate to replace lithium oxalate solution, phosphorus source in the present embodiment is phosphoric acid, also can adopt one or more mixing phosphorus sources in the organic phosphorus sources that contains P elements; Conductive additive in the present embodiment is acetylene black, and one or more that also can adopt carbon nano-tube, electrically conductive graphite in one or more or the inorganic conductive agent in other similar organic acid citric acids of physics and chemistry character or the glucose in ascorbic acid or machine carbohydrate, sucrose, fructose replace acetylene blacks; Liquid-phase reduction agent in the present embodiment is tetraethylene glycol, also can adopt one or more mixtures in ethylene glycol, triethylene glycol, glycerol, methyl-sulfoxide, diethylene glycol (DEG) to replace tetraethylene glycol; After above-mentioned substance is replaced, composite material character is without significant difference.
The surface sweeping electromicroscopic photograph that this embodiment prepares gained ferrous phosphate presoma as shown in Figure 1, X-ray diffractogram, stereoscan photograph, specific discharge capacity charging and discharging curve and the cyclic curve figure of the lithium iron phosphate/carbon composite material obtained therefrom and Fig. 2-Fig. 4, without essential distinction, repeat no more herein.0.1C first discharge specific capacity is 153mAh/g, the 1C first discharge specific capacity is 141mAh/g, and the 10C first discharge specific capacity is 112mAh/g.
Embodiment tetra-
1) ferrous phosphate powder outsourcing obtained is by lithium: iron: the stoichiometric proportion=1.02:0.98:1 of phosphorus adds the lithium source, the phosphorus source, and conductive additive, the quality of conductive additive is 20% of the LiFePO4 quality that makes, the liquid-phase reduction solvent is that 11:1 is transferred in three-necked bottle with the mol ratio of the LiFePO4 made, with regulating temp. electrothermal cover, heat, 100 ℃ water is evaporated after, atmospheric pressure reflux 4 hours under liquid-phase reduction agent solvent boiling point again, then slurry is moved to cucurbit mesolow distillation liquid phase reducing agent, course of reaction makes without high-temperature calcination and inert gas shielding the lithium iron phosphate positive material that surface coats one deck conductive agent.
2) the LiFePO4 inert nitrogen gas in step 1) is protected lower 600 ℃ of calcining 5h obtain the composite material of lithium iron phosphate/carbon.
In the present embodiment, the particle size D of described ferrous phosphate powder
50Between 1-5 μ m.
In the present embodiment, lithium source in the present embodiment is lithium nitrate solution, can adopt lithium hydroxide, lithium carbonate, lithium oxalate lithium acetate and in one or more mixtures replace lithium nitrate solutions, phosphorus source in the present embodiment is phosphoric acid, can adopt one or more mixing phosphorus sources in the organic phosphorus sources that contains P elements; Conductive additive in the present embodiment is electrically conductive graphite, and one or more that also can adopt carbon nano-tube, acetylene black in one or more or the inorganic conductive agent in other similar organic acid citric acids of physics and chemistry character or the glucose in ascorbic acid or machine carbohydrate, sucrose, fructose replace electrically conductive graphites; Liquid-phase reduction agent in the present embodiment is tetraethylene glycol, also can adopt one or more mixtures in ethylene glycol, triethylene glycol, glycerol, methyl-sulfoxide, diethylene glycol (DEG) to replace tetraethylene glycol; After above-mentioned substance is replaced, composite material character is without significant difference.
The surface sweeping electromicroscopic photograph that this embodiment prepares gained ferrous phosphate presoma as shown in Figure 1, X-ray diffractogram, stereoscan photograph, specific discharge capacity charging and discharging curve and the cyclic curve figure of the lithium iron phosphate/carbon composite material obtained therefrom and Fig. 2-Fig. 4, without essential distinction, repeat no more herein.0.1C first discharge specific capacity is 153mAh/g, the 1C first discharge specific capacity is 143mAh/g, and the 10C first discharge specific capacity is 114mAh/g.
Finally explanation is, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although with reference to preferred embodiment, the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, can modify or be equal to replacement technical scheme of the present invention, and not breaking away from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of claim scope of the present invention.
Claims (7)
1. the preparation method of lithium iron phosphate/carbon composite material for a high rate capability lithium ion battery is characterized in that: comprise the following steps:
A. prepare ferric lithium phosphate precursor: allocate the ferrous phosphate powder into He Lin source, lithium source and conductive additive according to the ratio of Li:Fe:P=1.02-1:0.98-1:1, then add the liquid-phase reduction agent and be heated to atmospheric pressure reflux under the boiling temperature of reducing agent solvent, finally reducing agent is separated from liquid-phase system, made ferric lithium phosphate precursor;
B. the ferric lithium phosphate precursor in step b is calcined under inert gas shielding to the composite material that obtains lithium iron phosphate/carbon.
2. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 1, it is characterized in that: in step a, the mol ratio of the described LiFePO4 that adds the liquid-phase reduction solvent and make is 8-12:1, and at atmospheric pressure reflux 4-10 hour; The addition of described conductive agent is the 5%-30% that wish prepares the LiFePO4 quality.
3. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 2, it is characterized in that: in step a, described liquid-phase reduction solvent is 10:1 with the mol ratio of the LiFePO4 made; The addition of described conductive agent be wish prepare the LiFePO4 quality 15%.
4. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 3, is characterized in that: the particle size D of ferrous phosphate powder in step a
50Between 1-5 μ m.
5. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 1, it is characterized in that: in step a, described lithium source is one or more mixtures in lithium hydroxide, lithium carbonate, lithium oxalate, lithium acetate and lithium nitrate; Described liquid-phase reduction solvent is one or more mixtures in ethylene glycol, diethylene glycol (DEG), triethylene glycol, tetraethylene glycol, methyl-sulfoxide, glycerol; Described conductive additive is one or both in citric acid, ascorbic acid, one or more mixtures of the inorganic conductive agent such as perhaps one or more mixtures in glucose, sucrose, fructose, or acetylene black, carbon nano-tube, electrically conductive graphite.
6. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 1; it is characterized in that: in step b, 550-750 ℃ of calcining 1-5h under the ferric lithium phosphate precursor inert gas shielding obtained to the composite material of lithium iron phosphate/carbon.
7. the preparation method of lithium iron phosphate/carbon composite material for high rate capability lithium ion battery according to claim 5; it is characterized in that: in step b, the lower 650 ℃ of calcining 1h of ferric lithium phosphate precursor inert gas shielding are obtained to the composite material of lithium iron phosphate/carbon.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103700855A (en) * | 2013-12-12 | 2014-04-02 | 天津巴莫科技股份有限公司 | Preparation method of high-performance lithium manganese phosphate material for lithium-ion power batteries |
| CN103700856A (en) * | 2013-12-12 | 2014-04-02 | 天津巴莫科技股份有限公司 | Preparation method of high-performance lithium manganese phosphate material for lithium-ion power batteries |
| CN103943856A (en) * | 2014-05-05 | 2014-07-23 | 西北大学 | Preparation method of phthalocyanine-lithium iron phosphate composite anode material |
| CN104393293A (en) * | 2014-11-20 | 2015-03-04 | 中物院成都科学技术发展中心 | Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material |
| CN113582152A (en) * | 2021-08-17 | 2021-11-02 | 江西省金锂科技股份有限公司 | Preparation method of low-cost lithium ion battery cathode material lithium iron phosphate |
| CN113582149A (en) * | 2021-05-31 | 2021-11-02 | 佛山市德方纳米科技有限公司 | Preparation method of flaky lithium iron phosphate material |
| CN114335517A (en) * | 2021-12-31 | 2022-04-12 | 欣旺达电动汽车电池有限公司 | Carbon composite lithium iron phosphate cathode material, preparation method and application thereof |
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| CN115465849A (en) * | 2022-09-26 | 2022-12-13 | 佛山市德方纳米科技有限公司 | Phosphate-series positive electrode material and preparation method and application thereof |
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Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103700855A (en) * | 2013-12-12 | 2014-04-02 | 天津巴莫科技股份有限公司 | Preparation method of high-performance lithium manganese phosphate material for lithium-ion power batteries |
| CN103700856A (en) * | 2013-12-12 | 2014-04-02 | 天津巴莫科技股份有限公司 | Preparation method of high-performance lithium manganese phosphate material for lithium-ion power batteries |
| CN103943856A (en) * | 2014-05-05 | 2014-07-23 | 西北大学 | Preparation method of phthalocyanine-lithium iron phosphate composite anode material |
| CN103943856B (en) * | 2014-05-05 | 2016-07-06 | 西北大学 | A kind of preparation method of phthalocyanine-iron phosphate compound anode material of lithium |
| CN104393293A (en) * | 2014-11-20 | 2015-03-04 | 中物院成都科学技术发展中心 | Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material |
| CN113582149A (en) * | 2021-05-31 | 2021-11-02 | 佛山市德方纳米科技有限公司 | Preparation method of flaky lithium iron phosphate material |
| CN113582152A (en) * | 2021-08-17 | 2021-11-02 | 江西省金锂科技股份有限公司 | Preparation method of low-cost lithium ion battery cathode material lithium iron phosphate |
| CN114335517A (en) * | 2021-12-31 | 2022-04-12 | 欣旺达电动汽车电池有限公司 | Carbon composite lithium iron phosphate cathode material, preparation method and application thereof |
| CN114335517B (en) * | 2021-12-31 | 2023-07-14 | 欣旺达电动汽车电池有限公司 | Carbon composite lithium iron phosphate positive electrode material, preparation method and application thereof |
| CN114927684A (en) * | 2022-06-23 | 2022-08-19 | 蜂巢能源科技股份有限公司 | Lithium iron phosphate cathode material, preparation method thereof and lithium ion battery |
| CN114927684B (en) * | 2022-06-23 | 2024-06-07 | 蜂巢能源科技股份有限公司 | Lithium iron phosphate positive electrode material, preparation method thereof and lithium ion battery |
| CN115465849A (en) * | 2022-09-26 | 2022-12-13 | 佛山市德方纳米科技有限公司 | Phosphate-series positive electrode material and preparation method and application thereof |
| CN115465849B (en) * | 2022-09-26 | 2024-05-10 | 佛山市德方纳米科技有限公司 | Phosphate positive electrode material and preparation method and application thereof |
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