WO2019201050A1 - 一种磷酸亚铁锂/碳复合材料的制备方法 - Google Patents

一种磷酸亚铁锂/碳复合材料的制备方法 Download PDF

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WO2019201050A1
WO2019201050A1 PCT/CN2019/078880 CN2019078880W WO2019201050A1 WO 2019201050 A1 WO2019201050 A1 WO 2019201050A1 CN 2019078880 W CN2019078880 W CN 2019078880W WO 2019201050 A1 WO2019201050 A1 WO 2019201050A1
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iron phosphate
phosphoric acid
composite material
lithium
carbon composite
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French (fr)
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韦伟峰
丁正平
戴宽
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中南大学
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • the invention relates to a preparation method of a cathode material for a lithium ion battery, in particular to a method for preparing a lithium iron phosphate/carbon composite material.
  • Lithium iron phosphate (LiFePO 4 ) cathode material with olivine structure has many advantages such as abundant raw material resources, low price, good thermal stability and chemical stability, long cycle life and high safety.
  • the electronic conductivity is poor (10 -10 ⁇ 10 -9 S / cm), and because lithium ions can only be transported along the [010] one-dimensional channel, lithium ion diffusion rate Low (approximately 10 -14 cm 2 /s), causing severe polarization during charging and discharging.
  • the materials are modified by coating, nanocrystallization, morphology control and element doping, and the electrochemical properties of the materials are improved.
  • nanocrystallization can shorten the time required for Li + and electrons to diffuse from the bulk phase to the electrolyte, and increase the diffusion rate of Li + ; surface coating can improve the transmission of electrons between the material interfaces.
  • the method disclosed in the patent CN101944601A uses a phase crystallization method to prepare a lithium iron phosphate precursor having a particle diameter of 20 to 100 nm, and then fully mixes with the nanometer carbon in a solution. Sintering gives a uniform carbon coated lithium iron phosphate. This carbon coating belongs to the synthetic coating, which increases the preparation process.
  • Patent CN103367722A for preparing a carbon-coated lithium iron phosphate composite material
  • the amphiphilic carbon material is compounded with ethylene glycol to form a suspension, and a lithium source including lithium hydroxide and a phosphorus source including phosphoric acid and sulfuric acid are added to the suspension.
  • the iron source of iron is subjected to a stirring reaction, and then placed in a high temperature reaction vessel for solvothermal reaction, and placed in a carbonization furnace for heat treatment to obtain a carbon-coated lithium iron phosphate composite material having a particle size of 30 to 100 nm.
  • a high-pressure reaction kettle is used for solvothermal reaction, and the process flow is complicated and the equipment requirements are high.
  • the invention aims to provide a preparation method of a lithium iron phosphate/carbon composite material, which can prepare a carbon coated nanometer lithium iron phosphate/carbon composite material, and the material has better rate performance and cycle performance.
  • the invention is achieved by the following scheme.
  • a method for preparing a lithium iron phosphate/carbon composite material comprising the steps of:
  • the aqueous solution of the oxidizing agent is added to the two solutions A and B obtained in the step (I), the mass concentration of the oxidizing agent is 0.1% to 50%; the reaction is 0.5 to 24 hours; the product after the reaction After separation, a solid polymer-coated nanometer iron phosphate precursor and a phosphoric acid solution 2 are obtained;
  • the oxidizing agent is selected from the group consisting of a peroxide oxidizing agent, an alkali metal persulfide, an ammonium persulfate, an alkali metal halide compound, a mixture of one or more of ammonium halophosphate, alkali metal hypohalite, ammonium hypohalite, benzoyl peroxide, benzoic acid peroxide, and dipropyl propyl peroxide;
  • step (III) After mixing the solid polymer-coated nanometer iron phosphate precursor obtained in the step (II) with a lithium source ball mill, the ratio of the polymer-coated nanometer iron phosphate precursor to the lithium source is 1 : (0.9 to 1.1), heat treatment is carried out under conditions containing a reducing atmosphere at a temperature of 500 to 800 ° C for 1 to 24 hours.
  • the solid polymer-coated nanometer iron phosphate precursor obtained in the (II) is washed and dried, and then used in the step (III).
  • the phosphoric acid solution 1 in the step (I) may be one in which the amount of the phosphoric acid required for the step (I) is separated by the phosphoric acid solution 2 after the step (II) reaction.
  • the resulting solution was prepared after mixing.
  • the organic monomer capable of polymerizing to form a conjugated chain in the step (I) is selected from the group consisting of dopamine, dopamine hydrochloride, vinylidene fluoride, thiophene, pyrrole, benzenesulfonic acid, aniline, phenylene, styrene ethylene, and diacetylene.
  • the organic compound which can be polymerized to form a conjugated chain is polymerized to form a conductive polymer compound by any one or a combination of them.
  • the reducing atmosphere in the step (III) is a mixed atmosphere in which the reducing atmosphere is a reducing gas, a reducing gas and nitrogen or/and an inert gas, or may be decomposed into a mixed atmosphere containing a reducing gas (such as ammonia gas) at a heat treatment temperature, and the reducing gas is Hydrogen or / and carbon monoxide.
  • a reducing gas such as ammonia gas
  • the preparation method of the invention has the following advantages:
  • the preparation method of the present invention can be prepared by one-step oxidation to obtain a polymer-coated precursor, so that the process is reduced and the process conditions are easily controlled as compared with the carbon coating after the synthesis.
  • the invention directly uses iron powder as an iron source, and the cost is low.
  • the phosphoric acid of one of the raw materials of the present invention can be recycled to reduce the production cost.
  • the lithium iron phosphate/carbon composite material prepared by the invention has a carbon layer thickness of 1 to 6 nm and a particle size of 10 to 80 nm, uniform carbon coating, good crystallinity and good rate performance. And loop performance,
  • the lithium hydroxide and the nanometer iron phosphate precursor are uniformly ball-milled, and then heated to 700 ° C at a heating rate of 2 ° C / min in a hydrogen atmosphere. After 6 hours of heat preservation, after natural cooling, a nano-iron iron phosphate composite material with a carbon layer thickness of 2 to 4 nm and a particle size of 50 nm was obtained.
  • the nano-lithium iron phosphate/carbon composite material prepared by the method of the invention was used to prepare a lithium ion battery to test its rate performance, and the results are shown in FIG. The results show that when the material is charged and discharged at 1C, the capacity of the battery can still reach 140mAhg -1 , and the lithium ion battery has good rate performance.
  • the lithium ion battery was tested for the cycle performance of the lithium iron phosphate/carbon composite prepared by the method of the present invention, and the results are shown in FIG. 2 .
  • the results show that at the 5C rate, after 160 cycles, the capacity retention rate is greater than 98%, and the lithium ion battery has good cycle performance.
  • the lithium carbonate and the nanometer iron phosphate were uniformly ball-milled and mixed in an argon-hydrogen mixed atmosphere (containing H 2 in a volume ratio of 5%) at 5 ° C / min.
  • the heating rate was raised to 750 ° C, and the temperature was kept for 10 h.
  • a surface-modified nano-lithium iron phosphate composite material having a carbon layer thickness of 1 to 3 nm and a particle size of 35 nm was obtained.
  • the lithium carbonate and the nanometer iron phosphate were uniformly ball-milled and mixed at a temperature of 2 ° C / min in a mixed atmosphere of carbon monoxide and nitrogen (containing 5% by volume of CO). The heating rate was raised to 650 ° C, and the temperature was kept for 8 h. After natural cooling, a surface-modified nano-lithium iron phosphate composite material having a carbon layer thickness of 3 to 5 nm and a particle size of 70 nm was obtained.
  • lithium hydroxide and nanometer iron phosphate were uniformly ball-milled and mixed in a gas mixture of nitrogen and hydrogen (containing H 2 in a volume ratio of 10%).
  • the temperature rise rate of °C/min was raised to 700 °C, and the temperature was kept for 8 hours.
  • a surface-modified nano-lithium iron phosphate composite material with a carbon layer thickness of 2 to 5 nm and a particle size of 40 nm was obtained.
  • the lithium carbonate and the nanometer iron phosphate are uniformly ball-milled and mixed in an atmosphere of argon gas and hydrogenation hydrocarbon gas (containing CO of 8% by volume).
  • the temperature rise rate of 3 ° C / min was raised to 650 ° C, and the temperature was kept for 5 h.
  • a surface-modified nano lithium iron phosphate composite material having a carbon layer thickness of 1 to 3 nm and a particle size of 60 nm was obtained.
  • the lithium carbonate and the nanometer iron phosphate are uniformly ball-milled and mixed, the ammonia gas is introduced into the device, and the temperature is raised to 800 ° C at a heating rate of 3 ° C / min, and the temperature is kept for 12 hours. After natural cooling, a surface-modified nano-lithium iron phosphate composite material having a carbon layer thickness of 1 to 2 nm and a particle size of 35 nm was obtained.
  • the lithium carbonate and the nanometer iron phosphate are uniformly ball milled and mixed with hydrogen, carbon monoxide and nitrogen (containing 8% by volume of CO and 5% of H2).
  • the temperature was raised to 1000 ° C at a temperature increase rate of 5 ° C / min, and the temperature was kept for 8 hours. After the temperature was naturally lowered, a surface-modified nano lithium iron phosphate composite material having a carbon layer thickness of 1 to 3 nm and a particle size of 20 nm was obtained.
  • the lithium hydroxide and the nanometer iron phosphate were uniformly ball-milled and mixed, and then heated to 850 ° C at a heating rate of 2 ° C / min in a carbon monoxide atmosphere, and kept for 10 hours. After cooling, a surface-modified nano lithium iron phosphate composite having a carbon layer thickness of 3 to 4 nm and a particle size of 35 nm was obtained.

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  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

一种表面包覆碳的纳米磷酸亚铁锂/碳复合材料的制备方法，将铁粉用磷酸溶解，将有机物单体溶解于水中，随后将上述所得两种溶液混合，缓慢加入氧化剂反应。再经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁前驱体；将得到的聚合物包覆的纳米磷酸铁前驱体与锂源均匀球磨混合后，在混合气氛中以一定的热处理温度处理一定的时间，获得纳米磷酸亚铁锂/碳复合材料。

Description

一种磷酸亚铁锂/碳复合材料的制备方法 技术领域
本发明涉及一种锂离子电池正极材料的制备方法，特别涉及一种磷酸亚铁锂/碳复合材料的制备方法。
背景技术
橄榄石结构的磷酸亚铁锂(LiFePO 4)正极材料具有原材料资源丰富，价格低廉，热稳定性和化学稳定性好，循环寿命长，安全性高等优点受到众多研究人员的关注。但是在实际的生产和应用中也存在一些不足，其电子导电性差(10 -10～10 -9S/cm)，而且由于锂离子只能沿着[010]一维通道传输，锂离子扩散速度低(约为10 -14cm 2/s)，使在充放电过程中极化严重。目前，主要采用导电材料包覆、纳米化、形貌控制和元素掺杂等方法对材料进行改性，提高材料的电化学性能。其中纳米化可以缩短Li +和电子从体相扩散至电解液所需的时间，提高Li +扩散速率；表面包覆可以改善电子在材料界面之间的传输。目前关于碳包覆制备纳米磷酸铁锂的研究较多，其中专利CN101944601A披露的方法采用相结晶法制得粒径为20～100nm的磷酸铁锂前驱体，再与纳米级炭在溶液中充分混合，烧结得到均匀炭包覆的纳米磷酸铁锂。这种碳包覆属于合成后的包覆，增加了制备工序。专利CN103367722A制备炭包覆磷酸铁锂复合材料的方法，将两亲性炭材料与乙二醇配制成悬浮液，在悬浮液中加入包括氢氧化锂的锂源和包括磷酸的磷源以及硫酸亚铁的铁源进行搅拌反应，再置于高温反应釜中进行溶剂热反应，并置于炭化炉中进行热处理，得到颗粒尺寸为30～100nm的炭包覆磷酸铁锂复合材料。合成过程中需使用高压反应釜进行溶剂热反应，工艺流 程复杂，设备要求高。
发明内容
本发明旨在提供一种磷酸亚铁锂/碳复合材料的制备方法，可制备得到碳包覆的纳米磷酸亚铁锂/碳的复合材料，材料的倍率性能和循环性能较佳。本发明通过以下方案实现。
一种磷酸亚铁锂/碳复合材料的制备方法，包括以下步骤：
(Ⅰ)将金属铁粉加入磷酸或/和磷酸溶液1中于25～100℃至完全溶解形成溶液A，将可聚合形成共轭链的有机物单体加入到水中溶解形成溶液B，有机物单体的质量浓度为0.1％～50％；金属铁粉与磷酸的物质的量比为(0.1～2):1；
(Ⅱ)在25～100℃，将步骤(Ⅰ)所得A、B两种溶液混合过程中向其中加入氧化剂水溶液，氧化剂的质量浓度为0.1％～50％；反应0.5～24h；反应后的产物经分离后得到固态的聚合物包覆的纳米磷酸铁前驱体和磷酸溶液2；所述氧化剂选自过氧化物类氧化剂、碱金属过硫化物、过硫化铵、碱金属卤酸盐类化合物、卤酸铵、碱金属次卤酸盐、次卤酸铵、过氧化苯甲酰、过氧化苯甲酸、过氧化二乙丙苯中的一种或多种混合物；
(Ⅲ)将步骤(Ⅱ)所得的固态的聚合物包覆的纳米磷酸铁前驱体与锂源球磨混合后，其中聚合物包覆的纳米磷酸铁前驱体与锂源的物质的量比为1:(0.9～1.1)，在含有还原气氛的条件下进行热处理，温度为500～800℃，时间1～24h。
为减少中间反应产物的杂质，使产品品质更优，在第(Ⅱ)所得的固态的聚合物包覆的纳米磷酸铁前驱体经洗涤—干燥后，再用于第(Ⅲ)步。
考虑到环保需要，在第(Ⅰ)步中的磷酸溶液1可以采用将所述第(Ⅱ)步反应后经分离的磷酸溶液2按第(Ⅰ)步所需的磷酸的物质的量与磷酸混合后制备得到的溶液。
第(Ⅰ)步中的可聚合形成共轭链的有机物单体选自多巴胺、盐酸多巴胺、偏氟乙烯、噻吩、吡咯、苯磺酸、苯胺、苯撑、苯撑乙烯和双炔等中的任意一种或几种的混合，这些可聚合形成共轭链的有机化合物经聚合反应后形成导电高分子类化合物。
第(Ⅲ)步的还原气氛为还原气氛为还原气体、还原气体与氮气或/和惰性气体的混合气氛或在热处理温度时可分解为包含还原气体(如氨气)的混和气氛，还原气体为氢气或/和一氧化碳。
与现有的制备方法相比，本发明的制备方法具有以下优点：
1、本发明的制备方法可以一步氧化制备得到聚合物包覆的前驱体，因此与合成后的碳包覆相比，减化了工序，工艺条件易于控制。
2、本发明直接采用铁粉作为铁源，成本低廉。
3、本发明的原材料之一的磷酸可循环使用，降低生产成本。
4、本发明所制得的纳米磷酸亚铁锂/碳复合材料，复合材料的碳层厚度1～6nm，颗粒尺寸为10～80nm，碳包覆均匀、结晶性好，有较好的倍率性能和循环性能，
附图说明
图1实施例1纳米磷酸铁锂/碳复合材料制作锂离子电池倍率性能测试结果
图2实施例1纳米磷酸铁锂/碳复合材料制作锂离子电池循环性能测试结果
具体实施方式
实施例1
将9g的铁粉，在温度为40℃、500r/min的条件下搅拌溶解于85mL质量浓度为20％的磷酸溶液中，将6g苯胺溶解于65mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以800r/min的速度高速搅拌，搅拌过程中缓慢滴加30mL质量分数为10％的过氧化氢，反应1h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁前驱体。按氢氧化锂与纳米磷酸铁前驱体摩尔比为1:1，将氢氧化锂和纳米磷酸铁前驱体均匀球磨混合后，于氢气气氛中，以2℃/min的升温速度升温至700℃，保温6h，自然降温后，得到碳层厚度为2～4nm、颗粒尺寸为50nm的表面包覆碳的纳米磷酸铁锂复合材料。
采用本发明方法制备的纳米磷酸铁锂/碳复合材料制作锂离子电池测试其倍率性能，结果如图1所示。结果表明，该材料在1C充放电时，电池的容量仍可达140mAhg -1，锂离子电池具有良好的倍率性能。
采用本发明方法制备的纳米磷酸铁锂/碳复合材料制作锂离子电池测试其循环性能，结果如图2所示。结果表明，在5C倍率下，经过160次循环,容量保持率大于98％，锂离子电池具有良好的循环性能。
实施例2
取40mL 85％的浓磷酸，加入96mL蒸馏水稀释至25％，随后加入15g铁粉，在温度为30℃、400r/min的条件下搅拌溶解，同时，将13g噻吩溶解于200mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以750r/min的速度高速搅拌，搅拌过程中缓慢加入20mL质量分数为30％的过氧化氢，反应3h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。
按碳酸锂与纳米磷酸铁的摩尔比1:1称取，将碳酸锂与纳米磷酸铁均匀球磨混合后，于氩氢混合气氛(含体积比5％的H 2)中以5℃/min的升温速度升温至750℃，保温10h，自然降温后，得到碳层厚度为1～3nm、颗粒尺寸为35nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例3
取68.4mL 85％的浓磷酸，加入513mL蒸馏水稀释至10％，随后加入17g铁粉，在常温、1000r/min的条件下搅拌溶解，同时，将8g吡咯溶解于300mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以2000r/min的速度高速搅拌，搅拌过程中缓慢加入5mL质量分数为1.0％的次氯酸钠，反应3h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。
按碳酸锂与纳米磷酸铁的摩尔比1:1称取，碳酸锂和纳米磷酸铁均匀球磨混合后，于一氧化碳和氮气(含体积比5％的CO)的混合气氛中以2℃/min的升温速度升温至650℃，保温8h，自然降温后，得到碳层厚度为3～5nm、颗粒尺寸为70nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例4
取40mL 85％的浓磷酸，加入96mL蒸馏水稀释至25％，随后加入15g铁粉，在常温、1000r/min的条件下搅拌溶解，同时，将10g吡咯溶解于100mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以1500r/min的速度高速搅拌，搅拌过程中缓慢加入8mL质量分数为1.0％的过氧化二乙丙苯，反应1h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。
按氢氧化锂与纳米磷酸铁的摩尔比1.05:1称取，氢氧化锂和纳米磷酸铁均匀球磨混合后，于氮气和氢气混合气(含体积比为10％的H 2)气氛中以2℃/min 的升温速度升温至700℃，保温8h，自然降温后，得到碳层厚度为2～5nm、颗粒尺寸为40nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例5
取20mL85％的浓磷酸，加入65mL蒸馏水稀释至20％，随后加入9g铁粉，在50℃、750r/min的条件下搅拌溶解，同时，将12g多巴胺溶解于300mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以1000r/min的速度高速搅拌，搅拌过程中缓慢加入10mL质量分数为30％的溴酸钾反应3h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。
按碳酸锂与纳米磷酸铁的摩尔比1:1称取，碳酸锂和纳米磷酸铁均匀球磨混合后，于氩气与一氢化碳氢混合气(含体积比为8％的CO)气氛中以3℃/min的升温速度升温至650℃，保温5h，自然降温后，得到碳层厚度为1～3nm、颗粒尺寸为60nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例6
取50mL 85％的浓磷酸，加入233mL蒸馏水稀释至15％，随后加入30g铁粉，在40℃、1000r/min的条件下搅拌溶解，同时，将15g多巴胺溶解于350mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以2000r/min的速度高速搅拌，搅拌过程中缓慢加入8mL质量分数为1.0％的过硫酸钠，反应2h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。
按碳酸锂与纳米磷酸铁的摩尔比1:1称取，碳酸锂和纳米磷酸铁均匀球磨混合后，装置中通入氨气，中以3℃/min的升温速度升温至800℃，保温12h，自然降温后，得到碳层厚度为1～2nm、颗粒尺寸为35nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例7
取20mL85％的浓磷酸，加入65mL蒸馏水稀释至20％，随后加入10g铁粉，在60℃、1500r/min的条件下搅拌溶解，同时，将12g多巴胺溶解于300mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以1500r/min的速度高速搅拌，搅拌过程中缓慢加入8mL质量分数为1.0％过氧化苯甲酸，反应6h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁，经分离的磷酸溶液与浓磷酸混合后制备得到20％的磷酸溶液，用于下一次的溶解铁粉。
按碳酸锂与纳米磷酸铁的摩尔比1.1:1称取，碳酸锂和纳米磷酸铁均匀球磨混合后，于氢气、一氧化碳和氮气(含体积比为8％的CO，5％的H2)的混合气氛中以5℃/min的升温速度升温至1000℃，保温8h，自然降温后，得到碳层厚度为1～3nm、颗粒尺寸为20nm的表面包覆修饰的纳米磷酸铁锂复合材料。
实施例8
取68.4mL 85％的浓磷酸，加入513mL蒸馏水稀释至10％，随后加入17g铁粉，在50℃、500r/min的条件下搅拌溶解，同时，将10g偏氟乙烯溶解于200mL蒸馏水中加热搅拌。随后将上述所得两种溶液混合并置于反应器中以1500r/min的速度高速搅拌，搅拌过程中缓慢加入10mL质量分数为1.0％的次氯酸铵，反应5h。混合溶液经过滤、洗涤、干燥后得到聚合物包覆的纳米磷酸铁。经分离的磷酸溶液与浓磷酸混合后制备得到10％的磷酸溶液，用于下一次的溶解铁粉。
按氢氧化锂与纳米磷酸铁的摩尔比1:1称取，氢氧化锂和纳米磷酸铁均匀球 磨混合后，于一氧化碳气氛中以2℃/min的升温速度升温至850℃，保温10h，自然降温后，得到碳层厚度为3～4nm、颗粒尺寸为35nm的表面包覆修饰的纳米磷酸铁锂复合材料。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合，为了避免不必要的重复，本发明对各种可能的组合方式不再另行说明。
此外，本发明的各种不同的实施方式之间也可以进行任意组合，只要其不违背本发明的思想，其同样应当视为本发明所公开的内容。

Claims (6)

  1. 一种磷酸亚铁锂/碳复合材料的制备方法，其特征在于：包括以下步骤，(Ⅰ)将金属铁粉加入磷酸或/和磷酸溶液1中于25～100℃至完全溶解形成溶液A，将可聚合形成共轭链的有机物单体加入到水中溶解形成溶液B，有机物单体的质量浓度为0.1％～50％；金属铁粉与磷酸的物质的量比为(0.1～2):1；
    (Ⅱ)在25～100℃，将步骤(Ⅰ)所得A、B两种溶液混合过程中向其中加入氧化剂水溶液，氧化剂的质量浓度为0.1％～50％；反应0.5～24h；反应后的产物经分离后得到固态的聚合物包覆的纳米磷酸铁前驱体和磷酸溶液2；所述氧化剂选自过氧化物类氧化剂、碱金属过硫化物、过硫化铵、碱金属卤酸盐类化合物、卤酸铵、碱金属次卤酸盐、次卤酸铵、过氧化苯甲酰、过氧化苯甲酸、过氧化二乙丙苯中的一种或多种混合物；
    (Ⅲ)将步骤(Ⅱ)所得的固态的聚合物包覆的纳米磷酸铁前驱体与锂源球磨混合后，其中聚合物包覆的纳米磷酸铁前驱体与锂源的物质的量比为1:(0.9～1.1)，在含有还原气氛的条件下进行热处理，温度为500～800℃，时间1～24h。
  2. 如权利要求1所述的一种磷酸亚铁锂/碳复合材料的制备方法，其特征在于：所述第(Ⅱ)所得的固态的聚合物包覆的纳米磷酸铁前驱体经洗涤—干燥后，用于第(Ⅲ)步。
  3. 如权利要求1所述的一种磷酸亚铁锂/碳复合材料的制备方法，其特征在于：在所述第(Ⅰ)步中的磷酸溶液1为将所述第(Ⅱ)步反应后经分离的磷酸溶液2按第(Ⅰ)步所需的磷酸的物质的量与磷酸混合后制备得到。
  4. 如权利要求1所述的一种磷酸亚铁锂/碳复合材料的制备方法，其特征在 于：所述第(Ⅰ)步中的可聚合形成共轭链的有机物单体选自多巴胺、盐酸多巴胺、偏氟乙烯、噻吩、吡咯、苯磺酸、苯胺、苯撑、苯撑乙烯和双炔等中的任意一种或几种的混合。
  5. 如权利要求1所述的一种磷酸亚铁锂/碳复合材料的制备方法，其特征在于：所述第(Ⅲ)步的还原气氛为还原气体、还原气体与氮气或/和惰性气体的混合气氛或在热处理温度时可分解为包含还原气体的混合气氛。
  6. 如权利要求5所述的一种磷酸亚铁锂/碳复合材料的制备方法，其特征在于：所述第(Ⅲ)步的还原气氛的还原气体为氢气或/和一氧化碳。
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