CN100361893C - Method of preparing carbon cladded ferrous lithium phosphate by using ironic phosphate - Google Patents
Method of preparing carbon cladded ferrous lithium phosphate by using ironic phosphate Download PDFInfo
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- CN100361893C CN100361893C CNB2006100252239A CN200610025223A CN100361893C CN 100361893 C CN100361893 C CN 100361893C CN B2006100252239 A CNB2006100252239 A CN B2006100252239A CN 200610025223 A CN200610025223 A CN 200610025223A CN 100361893 C CN100361893 C CN 100361893C
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- ferrous
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- tertiary iron
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Abstract
The present invention discloses a method for preparing carbon-wrapped ferrous lithium phosphate by using iron phosphate, namely, reductant is used for reducing ferric iron in the iron phosphate to ferrous iron and reacts with ammonium ions in solution at the same time to form non-crystalline ferrous ammonium phosphate. Then, the ferrous ammonium phosphate reacts with lithium acetate, ferrous lithium phosphate is obtained, and the carbon-wrapped ferrous lithium phosphate is obtained through carbon-wrapping treatment. Thereby, the obtained ferrous lithium phosphate has a good crystal structure. When the carbon-wrapped ferrous lithium phosphate is used as anode materials of a lithium ion battery, good electrochemical performance is showed, charge capacity is 169 mAh/g for the first time, discharge capacity is 163 mAh/g, and theory discharge capacity close to the anode materials of the ferrous lithium phosphate is 170 mAh/g. The method uses the iron phosphate as raw materials, and the present invention has advantages of low raw material cost, low processing cost, and simple technology line, and is suitable for large-scale production.
Description
Technical field
The present invention relates to a kind of preparation method of mineral compound, particularly prepare the preparation method of carbon cladded ferrous lithium phosphate with tertiary iron phosphate, it is used as the positive electrode material of lithium ion battery.
Background technology
LiFePO 4 (LiFePO
4) outstanding advantages such as material has abundant raw material, cost is low, specific storage is higher, environmentally friendly, nontoxic, Heat stability is good, becoming the research focus of various countries' researcher day by day, is a kind of lithium ion cell positive equivalent material of future generation that has much potentiality.The preparation method of ferrousphosphate lithium material mainly contains solid phase method, liquid phase method, microwave method and solid-liquid method mutually at present.
Solid phase method: mention among the Japanese Patent JP2000294238 Ferrox, Secondary ammonium phosphate and Quilonum Retard are carried out the ball milling mixing in acetone, and evaporate under nitrogen, thermal treatment obtains LiFePO 4 under 300-790 ℃ temperature afterwards.People such as A.K.Padhi (J.Electrochem.Soc.1997 (144): be raw material 1188),, obtain ferrousphosphate lithium material at 800 ℃ of sintering again 300-500 ℃ of pre-thermolysis with Quilonum Retard, Iron diacetate, primary ammonium phosphate.
Liquid phase method comprises sol-gel method, coprecipitation method, hydrothermal synthesis method etc.
Sol-gel method: by compatible Li
+, Fe
2+Or Fe
3+, PO
4 3-The aqueous solution select suitable organic agent that boils together, make it to add thermosetting colloidal sol and gel, obtain LiFePO 4 by sintering then.The existence that this method shortcoming is organic agent that boils together makes carbon content higher.
Coprecipitation method: lithium hydroxide is joined in the solution that contains ferrous ion and phosphoric acid, obtain post precipitation and make by sintering again.As with (NH
4)
2Fe (SO
4)
26H
2O, H
3PO
4, LiOH is raw material, water co-precipitation in the aqueous solution obtains throw out under the nitrogen protection, the compressing tablet roasting obtains product.
Hydrothermal synthesis method: the aqueous solution of tertiary iron phosphate, Trilithium phosphate is put into the autoclave of logical argon gas, and heating 1 hour is synthetic under 220 ℃, 2.4MPa condition.This method synthetic material electric conductivity is little, needs subsequent disposal, and needs high pressure high stable condition.
Microwave method: mention in the Chinese patent 200310121453.1 and adopt Quilonum Retard, Ferrox, primary ammonium phosphate, made the dispersion agent ball milling 4-12 hour, place crucible, put into 3-30 minute microwave oven treatment time to obtain ferrousphosphate lithium material with acetone.
For ferrousphosphate lithium material itself, the subject matter that exists comprises that electric conductivity is low at present.The method of improving the specific conductivity of LiFePO 4 concentrate on element doping and (or) surperficial coated with conductive material.
Solid reaction process is an industry member material preparation method commonly used, has for example successfully prepared LiCoO
2Material.But solid state reaction is solid/liquid/solid interface reaction basically, and reaction interface is little, so long reaction time, and needs repeatedly sintering, promptly grinds sintering again behind the sintering, and technology is loaded down with trivial details, the cycle is long.Even can not guarantee like this to react completely, in the high-temperature reaction process, may generate dystectic Trilithium phosphate Li
3PO
4With ferrous phosphate Fe
3(PO
4)
2, remaining unreacted impurity will worsen the chemical property of ferrousphosphate lithium material, and cause the consistence of material of different batches poor.And simple liquid phase reaction as sol-gel method, is beneficial to and reacts completely, but income is little, is feasible at the prepared in laboratory sample, tooling cost height during suitability for industrialized production.
Summary of the invention
The object of the present invention is to provide the method for preparing carbon cladded ferrous lithium phosphate with tertiary iron phosphate, promptly adopt reductive agent that the ferric iron in the tertiary iron phosphate is reduced into ferrous iron, simultaneously with solution in the ammonium ion reaction, form amorphous ferrous ammonium phosphate, ferrous ammonium phosphate and lithium acetate reaction then, coat through carbon again and handle, obtain the LiFePO 4 that carbon coats.
The present invention prepares carbon cladded ferrous lithium phosphate with tertiary iron phosphate the concrete steps of method are as follows:
(1) takes by weighing tertiary iron phosphate, reductive agent and ammoniacal liquor, wherein the mol ratio of tertiary iron phosphate and reductive agent is 2: 1 to 1: 5, the mol ratio of tertiary iron phosphate and ammoniacal liquor is 2: 1 to 1: 5, add distilled water, the concentration of reductive agent is 0.2-2mol/L, stirs then 1-10 hour, and the temperature of stirring is a room temperature to 90 ℃, refilter cleaning-drying and obtain amorphous ferrous ammonium phosphate, wherein reductive agent is sulfurous acid, ammonium sulphite, thiosulfuric acid or ammonium thiosulfate;
(2) amorphous ferrous ammonium phosphate mixes with lithium acetate, the mol ratio of wherein amorphous ferrous ammonium phosphate and lithium acetate is 99: 100 to 100: 99, under gas shield, handled 0.5-5 hour at 200-800 ℃, obtain LiFePO 4, take by weighing LiFePO 4 and carbon source again, wherein the mass ratio of LiFePO 4 and carbon source is 99: 1 to 85: 15, be dissolved in the distilled water and heated and stirred is mixed to evaporate to dryness, then under gas shield, handled 0.5 to 5 hour at 500 to 800 ℃, obtain carbon cladded ferrous lithium phosphate; Or with amorphous ferrous ammonium phosphate, lithium acetate and carbon source mixing; wherein the mol ratio of ferrous ammonium phosphate and lithium acetate is 99: 100 to 100: 99; the mass ratio of LiFePO 4 and carbon source is 99: 1 to 85: 15; under gas shield; handled 0.5-5 hour at 200-800 ℃, obtain carbon cladded ferrous lithium phosphate.
The carbon source that the present invention uses is sucrose, glucose, fructose or lactose.
The gas that the present invention uses is the mixed gas of argon gas, nitrogen, argon gas and hydrogen or the mixed gas of nitrogen and hydrogen, and hydrogen volume content is 2 to 10% in the mixed gas.
The present invention prepares the method for carbon cladded ferrous lithium phosphate with tertiary iron phosphate, has following advantage:
Combine the advantage of traditional solid phase and liquid phase method preferably, and avoid the shortcoming of the two effectively.The solid-liquid method is a kind of solid/liquid interfaces reaction, and the interface contact is big, helps improving the thoroughness of reaction, and has made full use of suitable these characteristics of suitability for industrialized production of solid phase method.Synthetic material loading capacity under the 0.2C condition reaches 163mAh/g, near theoretical value 170mAh/g, has promptly eliminated the influence of unreacted impurity effectively.The employing tertiary iron phosphate is starting material, and material cost and tooling cost are low, and operational path is simple, cycle weak point, batches of materials high conformity, energy consumption are low, very suitable scale volume production.
Description of drawings
The XRD spectra of the carbon cladded ferrous lithium phosphate that Fig. 1 obtains for embodiment 1.
Fig. 2 is the carbon cladded ferrous lithium phosphate of embodiment 2 preparation during as anode material for lithium-ion batteries, the charging and discharging curve of battery.
Embodiment
Can further understand the present invention from following examples, but the present invention not only is confined to following examples.
Embodiment 1
(1) add 0.2mol tertiary iron phosphate, 0.2mol ammonium thiosulfate, 0.1mol ammoniacal liquor and 400mL distilled water in beaker, stirred then 8 hours, the temperature of stirring is a room temperature, refilters cleaning-drying and obtains the amorphous ferrous ammonium phosphate of 37.2g;
(2) the amorphous ferrous ammonium phosphate of 37.2g is mixed with the 20.4g lithium acetate, under nitrogen and the protection of 5% hydrogen gas mixture, handled 3 hours, obtain the 31.5g LiFePO 4 at 400 ℃; 3.5g glucose is dissolved in the 50mL distilled water and with 31.5g LiFePO 4 mixing post-heating is stirred to evaporate to dryness, under nitrogen protection, handled 1 hour then, obtain the 32.8g carbon cladded ferrous lithium phosphate at 700 ℃.Fig. 1 is the XRD spectra that embodiment 1 obtains carbon cladded ferrous lithium phosphate, shows that LiFePO 4 has good crystalline structure.
Embodiment 2
(1) add 0.2mol tertiary iron phosphate, 0.4mol ammonium sulphite, 0.3mol ammoniacal liquor and 500mL distilled water in beaker, stirred then 5 hours, the temperature of stirring is 50 ℃, refilters cleaning-drying and obtains the amorphous ferrous ammonium phosphate of 37.2g;
(2) the amorphous ferrous ammonium phosphate of 37.2g is mixed with the 20.5g lithium acetate, under argon gas and the protection of 5% hydrogen gas mixture, handled 2 hours, obtain the 31.5g LiFePO 4 at 500 ℃; 2.4g sucrose is dissolved in the 50mL distilled water, is stirred to evaporate to dryness with 31.5g LiFePO 4 mixing post-heating again, under argon gas and the protection of 5% hydrogen gas mixture, handled 2 hours then, obtain the 32.5g carbon cladded ferrous lithium phosphate at 650 ℃.
Embodiment 3
(1) add 0.2mol tertiary iron phosphate, 0.4mol ammonium sulphite, 0.4mol ammoniacal liquor and 400mL distilled water in beaker, stirred then 8 hours, the temperature of stirring is 70 ℃, refilters cleaning-drying and obtains the amorphous ferrous ammonium phosphate of 37.2g;
(2) the amorphous ferrous ammonium phosphate of 37.2g, 20.4g lithium acetate and 3.5g fructose are mixed; add 50mL distilled water; make dissolving of lithium acetate and fructose and heated and stirred to evaporate to dryness; then under argon gas and the protection of 5% hydrogen gas mixture; handled 5 hours at 700 ℃, obtain the 32.8g carbon cladded ferrous lithium phosphate.
Embodiment 4
Carbon cladded ferrous lithium phosphate that embodiment 2 is prepared and conductive agent acetylene black, caking agent ptfe emulsion uniform mixing in ethanolic soln, the mass ratio of carbon cladded ferrous lithium phosphate, acetylene black and caking agent is 80: 10: 10, compressing tablet makes positive pole to aluminium foil then.Adopt metallic lithium as negative pole, the solution of lithium hexafluoro phosphate-NSC 11801 of 1mol/L-methylcarbonate is as electrolytic solution, the porous polyethylene membrane that 20 μ m are thick is a barrier film, be assembled into button-type lithium cell and carry out charge-discharge test, obtain the charging and discharging curve of carbon cladded ferrous lithium phosphate positive electrode material, as shown in Figure 2.The initial charge capacity is 169mAh/g, and loading capacity is 163mAh/g, near the theoretical loading capacity 170mAh/g of ferrous phosphate doping lithium anode material.
Claims (3)
1. the method for preparing carbon cladded ferrous lithium phosphate with tertiary iron phosphate is characterized in that the preparation method is as follows:
(1) takes by weighing tertiary iron phosphate, reductive agent and ammoniacal liquor, wherein the mol ratio of tertiary iron phosphate and reductive agent is 2: 1 to 1: 5, the mol ratio of tertiary iron phosphate and ammoniacal liquor is 2: 1 to 1: 5, add distilled water, the concentration of reductive agent is 0.2-2mol/L, stirs then 1-10 hour, and the temperature of stirring is a room temperature to 90 ℃, refilter cleaning-drying and obtain amorphous ferrous ammonium phosphate, wherein reductive agent is sulfurous acid, ammonium sulphite, thiosulfuric acid or ammonium thiosulfate;
(2) amorphous ferrous ammonium phosphate mixes with lithium acetate, the mol ratio of wherein amorphous ferrous ammonium phosphate and lithium acetate is 99: 100 to 100: 99, under gas shield, handled 0.5-5 hour at 200-800 ℃, obtain LiFePO 4, take by weighing LiFePO 4 and carbon source again, wherein the mass ratio of LiFePO 4 and carbon source is 99: 1 to 85: 15, be dissolved in the distilled water and heated and stirred is mixed to evaporate to dryness, then under gas shield, handled 0.5 to 5 hour at 500 to 800 ℃, obtain carbon cladded ferrous lithium phosphate; Or with amorphous ferrous ammonium phosphate, lithium acetate and carbon source mixing; wherein the mol ratio of ferrous ammonium phosphate and lithium acetate is 99: 100 to 100: 99; the mass ratio of LiFePO 4 and carbon source is 99: 1 to 85: 15; under gas shield; handled 0.5-5 hour at 200-800 ℃, obtain carbon cladded ferrous lithium phosphate.
2. according to claim 1ly prepare the method for carbon cladded ferrous lithium phosphate, it is characterized in that carbon source is sucrose, glucose, fructose or lactose with tertiary iron phosphate.
3. according to claim 1ly prepare the method for carbon cladded ferrous lithium phosphate, it is characterized in that gas is the mixed gas of argon gas, nitrogen, argon gas and hydrogen or the mixed gas of nitrogen and hydrogen with tertiary iron phosphate; Hydrogen volume content is 2 to 10% in the mixed gas.
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| CN100361893C true CN100361893C (en) | 2008-01-16 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101209822B (en) * | 2006-12-31 | 2011-03-02 | 比亚迪股份有限公司 | Preparation method for lithium ion secondary battery positive pole active substance lithium iron phosphate |
| JP4317239B2 (en) | 2007-04-27 | 2009-08-19 | Ｔｄｋ株式会社 | Method for producing composite particles for electrodes |
| JP5223281B2 (en) | 2007-09-28 | 2013-06-26 | Ｔｄｋ株式会社 | Lithium ion secondary battery or composite particle for positive electrode of lithium secondary battery, and lithium ion secondary battery or lithium secondary battery |
| WO2009117871A1 (en) * | 2008-03-28 | 2009-10-01 | Byd Company Limited | A method of preparing a lithium iron phosphate cathode material for lithium secondary batteries |
| CN109148878B (en) * | 2018-09-03 | 2020-02-14 | 东莞塔菲尔新能源科技有限公司 | Method for treating residual lithium on surface of lithium-containing positive electrode material, positive electrode material and lithium ion battery |
| CN110970605A (en) * | 2018-09-30 | 2020-04-07 | 深圳市贝特瑞纳米科技有限公司 | Carbon-coated ferrous phosphate, preparation method, carbon-coated lithium iron phosphate prepared by using carbon-coated ferrous phosphate and application |
| CN111115608B (en) * | 2019-12-20 | 2022-06-28 | 大连博融新材料有限公司 | Ferrous ammonium phosphate, preparation method and application thereof |
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| CN1431147A (en) * | 2003-02-17 | 2003-07-23 | 郑绵平 | Wet chemistry method for preparing lithium iron phosphate |
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| JP2005190882A (en) * | 2003-12-26 | 2005-07-14 | Sumitomo Osaka Cement Co Ltd | Manufacturing method of positive electrode active material for lithium battery, positive electrode active material for lithium battery, electrode for lithium battery, and lithium battery |
| CN1649189A (en) * | 2004-12-29 | 2005-08-03 | 浙江大学 | Method for preparing carbon coated lithium ferrous phosphate composite material including metal conductive agent |
| WO2005095273A1 (en) * | 2004-03-30 | 2005-10-13 | Seimi Chemical Co., Ltd. | Method for producing lithium-iron composite oxide |
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- 2006-03-30 CN CNB2006100252239A patent/CN100361893C/en not_active Expired - Fee Related
Patent Citations (6)
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| JP2001307726A (en) * | 2000-04-24 | 2001-11-02 | Yuasa Corp | Electrode material and battery using the same |
| CN1431147A (en) * | 2003-02-17 | 2003-07-23 | 郑绵平 | Wet chemistry method for preparing lithium iron phosphate |
| JP2005190882A (en) * | 2003-12-26 | 2005-07-14 | Sumitomo Osaka Cement Co Ltd | Manufacturing method of positive electrode active material for lithium battery, positive electrode active material for lithium battery, electrode for lithium battery, and lithium battery |
| WO2005095273A1 (en) * | 2004-03-30 | 2005-10-13 | Seimi Chemical Co., Ltd. | Method for producing lithium-iron composite oxide |
| CN1649189A (en) * | 2004-12-29 | 2005-08-03 | 浙江大学 | Method for preparing carbon coated lithium ferrous phosphate composite material including metal conductive agent |
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Non-Patent Citations (1)
| Title |
|---|
| 锂离子电池正极材料LiFePO4的微波合成及结构表征. 李于华等.分子科学学报，第21卷第5期. 2005 * |
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