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WO2012045211A1 - 一种锂亚铁磷酸复盐正极材料的制备方法以及制得的正极材料 - Google Patents

一种锂亚铁磷酸复盐正极材料的制备方法以及制得的正极材料 Download PDF

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Publication number
WO2012045211A1
WO2012045211A1 PCT/CN2010/077619 CN2010077619W WO2012045211A1 WO 2012045211 A1 WO2012045211 A1 WO 2012045211A1 CN 2010077619 W CN2010077619 W CN 2010077619W WO 2012045211 A1 WO2012045211 A1 WO 2012045211A1
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Prior art keywords
lithium
iron
ferrous
solution
phosphate
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English (en)
French (fr)
Inventor
赵林治
李中东
李荣富
冯祥明
李春生
赵培正
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HENAN HUANYU GROUP CO Ltd
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HENAN HUANYU GROUP CO Ltd
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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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • 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

Definitions

  • the invention relates to a novel method for preparing lithium ferrous phosphate double salt cathode material by using iron filings, phosphoric acid and lithium hydroxide, belonging to the field of new energy materials.
  • Lithium-ion secondary battery is a new generation of green energy. It is mainly composed of three materials: positive electrode, negative electrode and electrolyte. It has the advantages of high energy density, high cycle performance, low self-discharge rate, no memory effect and wide operating temperature range. It has been widely used in mobile phones, laptops, video cameras, power tools, etc., and is rapidly entering the field of electric vehicles.
  • LiCo0 2 , LiNi0 2 , LiMn 2 0 4 . 1 ⁇ 0 ⁇ 2 is a relatively large-scale commercialized cathode material.
  • the research is mature and the comprehensive performance is excellent, but the price is high and the capacity is low.
  • LiNi0 2 has lower cost and higher capacity, but it is difficult to prepare, and the consistency and reproducibility of material properties are poor, and there are serious safety problems.
  • Spinel LiMn 2 0 4 has low cost and good safety, but its capacity is low.
  • the Tahti- Teller effect occurs during deep discharge, which affects the stability of the material structure and the high temperature cycle performance of the material.
  • the layered LiMn0 2 has a large specific capacity, but it belongs to the thermodynamic metastable state, the structure is unstable, and there is a Jahn-Teller effect and the cycle performance is poor.
  • Layered LiNi x Co y Mn 1-xy 0 2 series materials such as LiNi 1/3 Co 1/3 Mn 1/3 0 2 better combine the advantages of the three, make up for their respective shortcomings With high specific capacity, low cost, stable cycle performance and good safety performance, it is a strong competitor for the next generation of lithium ion battery cathode materials, but there are still many industrial synthesis processes, poor preparation repeatability, powder The filling property of the body is not ideal, and the expensive Ni and Co elements have a high proportion.
  • the Goodenough working group found that the olivine olivine structure of LiFeP0 4 has an oxidation-reduction potential of 3.4 V, good cycle performance, and a theoretical capacity of 170 mAh/g, which has attracted great interest from scientists and many companies.
  • the olivine structure of LiFeP0 4 I has stable voltage, excellent platform characteristics, high capacity, stable structure, high temperature performance and cycle performance, safety, non-toxicity and low cost. From the current development situation, and from the long-term perspectives of cost performance, resources and environment, LiFeP0 4 is a promising cathode material for a new generation of lithium ion secondary batteries.
  • the object of the present invention is to provide a novel method for preparing a lithium ferrous phosphate double salt cathode material which has a long life, a low tap density and a low specific capacity, which is prepared from iron filings, phosphoric acid and lithium hydroxide.
  • the invention provides a novel method for preparing lithium ferrous phosphate double salt cathode material by using iron filings, phosphoric acid and lithium hydroxide, which comprises the following steps:
  • the phosphoric acid solution reacts with the iron filings.
  • the pH of the reaction solution is 1.5, the specific gravity is 1.25 ⁇ 1.32, the reaction liquid is collected; under the inert gas protection condition, the reaction liquid is concentrated by vacuum evaporation, and the crystal is cooled to obtain solid dihydrogen phosphate.
  • Iron and mother liquor
  • the solid dihydrogen phosphate is dissolved in water to obtain solution B under inert gas protection conditions, and the solution B is sufficiently reacted with the lithium hydroxide solution to form a colloidal suspension C;
  • the suspension D is spray-dried to obtain a lithium iron phosphate precursor E;
  • the lithium iron phosphate precursor E is calcined twice under a weak reducing atmosphere, the first calcination temperature is 450-500 ° C, and the second calcination temperature is 650-750 ° C, and the ferrous iron is directly obtained.
  • Synthetic lithium ferrous iron phosphate double salt microcrystals and ferric iron pyrolysis carbon reduction method lithium ferrous phosphate double salt crystallites and pyrolytic carbon crystallites uniformly mixed lithium ion battery cathode material.
  • a novel method for preparing a lithium ferrous phosphate double salt cathode material using iron filings, phosphoric acid or lithium hydroxide according to the present invention the concentration of the phosphoric acid solution is 2.7 to 3.2 moles / liter.
  • a novel method for preparing a lithium ferrous phosphate double salt cathode material using iron filings, phosphoric acid or lithium hydroxide according to the present invention the temperature at which the phosphoric acid solution reacts with the iron filings is maintained at 50 to 70 °C.
  • a novel method for preparing a lithium ferrous phosphate double salt cathode material using iron filings, phosphoric acid, and lithium hydroxide according to the present invention the solid ferrous dihydrogen phosphate, the lithium hydroxide, the iron hydroxide, and pyrolytic carbon
  • the molar ratio is (1.00): (2.00-2.05): (0.96-1.00): (0.9-1.8).
  • the invention discloses a novel method for preparing a lithium ferrous phosphate double salt cathode material by using iron filings, phosphoric acid and lithium hydroxide:
  • the weak reducing atmosphere is a mixed gas of 5-15% hydrogen and 95-85% nitrogen or argon or 100 parts of ammonia decomposition gas and 400 to 67 parts of a mixed gas of nitrogen or argon.
  • the pyrolytic carbon source is selected from any one of sucrose, glucose, citric acid, starch, and polyvinyl alcohol. kind or any of several.
  • Figure 1 is an X-ray diffraction pattern of a positive electrode material
  • Fig. 2 shows a 18650 type 1200mAh cylindrical lithium ion battery prepared by using a positive electrode material as a positive electrode active material. 1. 0C charge, respectively, 0. 2C, 1C, 5C discharge curve.
  • Figure 3 is a 18650 type 1200mAh cylindrical lithium ion battery prepared by using a positive electrode material as a positive electrode active material. IOC discharge cycle curve.
  • Scrap iron scraps Scrap iron scraps from hardware factories producing battery components in the battery industry, porous scrap iron strip materials such as Baosteel's BDCK or SPCC: The impurities contained therein are only slightly higher in manganese (Mn ⁇ 0.3%), but manganese is harmless and beneficial. Doping element.
  • the scrap iron scrap is filled from the top feed port to the vertical reactor, and the 2.9 mol/L phosphoric acid solution enters from the lower part of the reactor until the full immersion iron scrap is near the upper reaction liquid overflow port, and the 2.9 mol/L phosphoric acid solution is commercially available.
  • % phosphoric acid and water are mixed according to a volume ratio of 1:4; the jacket is heated to keep the temperature of the lower part of the reactor at 50-60 ° C.
  • the reaction liquid flows from the upper reaction liquid overflow port (10 cm lower than the liquid surface) through the solid-liquid separator to continuously remove the solid impurities, and then continuously flows into the inert gas protection liquid storage tank; the hydrogen generated by the reaction is vented from the top exhaust pipe to the outside, The condensed water in the tube flows back to the reaction tank.
  • reaction liquid Under inert gas protection conditions, the reaction liquid is sucked from the liquid storage tank into a vacuum evaporator, and concentrated by vacuum evaporation, and the crystal is cooled, centrifuged and dried to obtain solid dihydrogen phosphate and mother liquor, and the separated mother liquid is used for recycling with the phosphoric acid solution. Under the inert gas protection condition, the solid dihydrogen phosphate is redissolved in water to obtain solution B.
  • Fe Chemical analysis knows Fe:
  • the system is in a colloidal suspension C state
  • the colloidal suspension C was added with 25.7 g of sucrose per mole according to the contained ferrous dihydrogen phosphate, and completely dissolved; the colloidal suspension C was continuously added to the original equimolar iron dihydrogen phosphate under stirring. Preparation of the iron hydroxide colloid to obtain a colloidal suspension D;
  • the above molar ratio of solid ferrous dihydrogen phosphate, lithium hydroxide, iron hydroxide and pyrolytic carbon is 1.00: 2.00: 1.00: (0.5+0.4), wherein 0.5 mole of pyrolytic carbon is used for high temperature reduction of ferric iron, 0.4
  • the molar pyrolysis carbon retains the conductive carbon as a product in the product.
  • the colloidal suspension D has a very homogeneous phase.
  • the suspension D was spray-dried to obtain a spherical particle precursor E, and the spray was rapidly dried so that the chemical composition of each spherical particle in the precursor E maintained the uniform consistency of the colloidal suspension D.
  • a weak reducing atmosphere 100 parts by volume of ammonia decomposition gas and 100 parts by volume of nitrogen
  • calcination at 500 ° C for 8 hours and calcination at 700 ° C for 15 hours
  • two reaction principles of the same raw material system were obtained simultaneously to form LiFeP0 4 nanocrystallite particles.
  • the submicron particles uniformly coated and bridged by the pyrolytic carbon, thereby obtaining a lithium ferrous phosphate double salt lithium ion battery cathode material having a high tap density and a high capacity.
  • Fig. 1 is an X-ray diffraction spectrum of a lithium ferrous phosphate double salt cathode material
  • Fig. 2 and Fig. 3 are electrochemical performance diagrams of a lithium ferrous phosphate double salt cathode material. Since the direct synthesis contains ferrous salts and ferric LiFeP0 4 hot synthesis LiFeP0 4 carbon reduction, so that the normal single principle XRD pattern obtained LiFeP0 4 are not identical, but only because LiFeP0 4 orthorhombic a crystalline form of The difference is only in the difference in grain shape and cell parameter values, which is manifested by the fact that the order of the peaks of the strongest diffraction peaks is different.
  • Scrap iron scraps Scrap iron scraps from hardware factories producing battery components in the battery industry, porous scrap iron strip materials such as Baosteel's BDCK or SPCC: The impurities contained therein are only slightly higher in manganese (Mn ⁇ 0.3%), but manganese is harmless and beneficial. Doping element.
  • the scrap iron scrap is filled from the top feed port to the vertical reactor, and the 2.7 mol/L phosphoric acid solution enters from the lower part of the reactor until the full immersion iron scrap is near the upper reaction liquid overflow port, and the 2.7 mol/L phosphoric acid solution is commercially available.
  • reaction liquid flows from the upper reaction liquid overflow port (10 cm lower than the liquid surface) through the solid-liquid separator to remove solid impurities and continuously flows into the inert gas protection liquid storage tank;
  • the hydrogen is vented from the top exhaust pipe to the outside, and the condensed water in the pipe flows back to the reaction tank.
  • reaction liquid Under inert gas protection conditions, the reaction liquid is sucked from the liquid storage tank into a vacuum evaporator, and concentrated by vacuum evaporation, and the crystal is cooled, centrifuged and dried to obtain solid dihydrogen phosphate and mother liquor, and the separated mother liquid is used for recycling with the phosphoric acid solution. Under the inert gas protection condition, the solid dihydrogen phosphate is redissolved in water to obtain solution B.
  • Fe Chemical analysis knows Fe:
  • the colloidal suspension C was added with 50g of sucrose per mole of ferrous phosphate containing hydrogen under stirring and completely dissolved; the colloidal suspension C was continuously added to the original prepared 0.98-fold molar of dihydrogen phosphate.
  • Iron hydroxide colloid obtained colloidal suspension D;
  • LiFeP0 4 is prepared by the high temperature carbon reduction method with Li3 ⁇ 4P0 4 :
  • the colloidal suspension D has a very homogeneous phase. It is known that all components are equimolar Li + +Fe 2+ P0 4 3 _ (synthetic LiFeP0 4 ) and equimolar Li + +Fe 3+ +P0 4 3 _ (synthesis LiFeP0 4 , but the ferric iron is firstly reduced by hot carbon) uniformly mixed multiphase system; spray suspension D is sprayed to obtain spherical particle precursor E, and the spray is rapidly dried to maintain the chemical composition of each spherical particle in the precursor E Uniform consistency of the colloidal suspension D.
  • Example 3 Scrap iron scraps: Waste iron scraps from hardware factories producing battery components in the battery industry, porous scrap iron strip materials such as Baosteel's BDCK or SPCC: the impurities contained therein are only slightly higher in manganese (Mn ⁇ 0.3%), but manganese It is a harmless and beneficial doping element.
  • the scrap iron scrap is filled from the top feed port to the vertical reactor, and the 3.2 mol/L phosphoric acid solution enters from the lower part of the reactor until the full immersion iron scrap is near the upper reaction liquid overflow port, and the 3.2 mol/L phosphoric acid solution is commercially available.
  • the reaction liquid flows from the upper reaction liquid overflow port (10 cm lower than the liquid surface) through the solid-liquid separator to continuously remove the solid impurities, and then continuously flows into the inert gas protection liquid storage tank; the hydrogen generated by the reaction is vented from the top exhaust pipe to the outside, The condensed water in the tube flows back to the reaction tank.
  • the reaction liquid is sucked from the liquid storage tank into a vacuum evaporator, and concentrated by vacuum evaporation, and the crystal is cooled, centrifuged and dried to obtain solid dihydrogen phosphate and mother liquor, and the separated mother liquid is used for recycling with the phosphoric acid solution.
  • the solid ferrous dihydrogen phosphate is redissolved in water to obtain solution B.
  • F e: P 1.4501 mol / L: 2.9588 mol / L, solution B under stirring and dihydrogen phosphate Ferrous (in terms of P0 4 ) 2.02 times mole
  • the lithium hydroxide solution is fully reacted, and the reactions that may occur here are
  • the system is in a colloidal suspension C state
  • the colloidal suspension C was added with 32.8 g of sucrose per mole of ferrous iron dihydrogen phosphate under stirring and completely dissolved;
  • the colloidal suspension C is continuously added to the colloid suspension D which is the newly prepared iron hydroxide colloid containing the equimolar amount of dihydrogen phosphate dihydrogen;
  • the above molar ratio of solid ferrous dihydrogen phosphate, lithium hydroxide, ferric hydroxide and pyrolytic carbon is 1.00: 2.04: 1.00: (0.5+0.65), wherein 0.5 mole of pyrolytic carbon is used for reducing ferric iron, 0.65 mole Pyrolytic carbon retains the conductive carbon in the product as a product.
  • the colloidal suspension D has a very homogeneous phase. It is known that all components are equimolar Li + +Fe 2+ P0 4 3 _ (synthetic LiFeP0 4 ) and equimolar Li + +Fe 3+ +P0 4 3 _ (synthesis a multiphase system in which LiFeP0 4 , but trivalent iron is first reduced by hot carbon);
  • the suspension D was spray-dried to obtain a spherical particle precursor E, and the spray was rapidly dried so that the chemical composition of each spherical particle in the precursor E maintained the uniform consistency of the colloidal suspension D.
  • the carbon is evenly coated and bridged by submicron particles, thereby obtaining a lithium ferrous ferrous phosphate double salt lithium ion battery cathode material with uniform product.
  • the invention discloses a novel method for preparing lithium ferrous phosphate double salt cathode material by using iron filings, phosphoric acid and lithium hydroxide, and is a wet solution solution precipitation method lithium ferrous phosphate double salt crystal nucleus and hot carbon reduction method in the same raw material system.
  • Lithium ferrous iron phosphate complex salt nucleus and conductive agent pyrolyze carbon crystal nucleus, or simultaneously generate co-growth, thereby forming a uniform body of lithium ferrous phosphate double salt microcrystals coated and bridged by pyrolytic conductive carbon, Very good electrical conductivity, electrochemical performance and processing properties.

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Description

一种锂亚铁磷酸复盐正极材料的制备方法以及制得的正极材料 技术领域
本发明涉及一种用铁屑、 磷酸、 氢氧化锂制备锂亚铁磷酸复盐正极材料的新方法， 属 新能源材料领域。
背景技术
发展新能源、 低碳经济和节能减排已成为世界各国发展的当务之急， 电动汽车及新能 源汽车是二十一世纪汽车工业发展新的里程碑， 对缓解全球能源危机， 加强环境保护具有 特殊和深远意义。
锂离子二次电池是新一代绿色能源， 它主要是由正极、 负极、 电解质三大材料组成， 具有高能量密度、 高循环性能、 低自放电率、 无记忆效应、 工作温度范围宽等优点。 目前 已在移动电话、 手提电脑、 摄像机、 电动工具等诸多领域广泛应用， 并且正在快速向电动 车领域进军。
目前， 研究最多的锂离子二次电池正极材料是 LiCo02、 LiNi02、 LiMn204。 1^0〇2是 较早大规模商品化的正极材料， 研究比较成熟， 综合性能优良， 但价格昂贵， 容量较低。 LiNi02成本较低， 容量较高， 但制备困难， 材料性能的一致性和重现性差， 存在较为严重 的安全问题。 尖晶石 LiMn204成本低， 安全性好， 但容量低， 在深度放电时发生 Tahti- Teller效应， 影响材料结构的稳定性， 材料的高温循环性能差。 层状 LiMn02比容量较大， 但其属于热力学亚稳态， 结构不稳定， 存在 Jahn-Teller效应而循环性能较差。 层状 LiNixCoyMn1-x-y02系列材料 （简称三元材料） 如 LiNi1/3Co1/3Mn1/302较好地兼备了三者的优 点， 弥补了各自的不足， 具有高比容量、 成本较低、 循环性能稳定、 安全性能较好等特 点， 是下一代锂离子电池正极材料的有力竞争者， 但仍有工业合成工艺较为繁复， 前驱体 制备重复性差， 粉体的填充性不理想， 昂贵的 Ni、 Co元素比例较高等问题。
1997年 Goodenough工作组发现正交橄榄石结构的 LiFeP04的氧化还原电位为 3.4V， 循环性能较好， 理论容量达到 170mAh/g， 引起广大科学工作者和许多公司的极大兴趣。 橄榄石结构的 LiFeP04I作电压平稳、 平台特性优良、 容量较高、 结构稳定、 高温性能和 循环性能好、 安全无毒、 成本低廉。 从目前发展状况看， 以及从性价比、 资源和环境等长 远观点考虑， LiFeP04是很有前途的新一代锂离子二次电池正极材料。 但从电动车范围广 泛试用的情况看， 目前生产的磷酸亚铁锂存在问题是： 材料的均匀性尚难满足使用十年普 遍要求， 振实密度小， 比容量较低等。 发明公开 本发明的目的是提供一种用铁屑、 磷酸、 氢氧化锂制备的寿命长、 振实密度较小、 比 容量较低的锂亚铁磷酸复盐正极材料的新方法。 本发明所提供的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法， 包括如下步骤：
磷酸溶液与铁屑反应， 当反应液的 pH值^ 1.5， 比重 =1.25~1.32时， 收集反应液； 在惰性气体保护条件下所述反应液真空蒸发浓缩， 并冷却结晶得固体磷酸二氢亚铁和 母液；
在惰性气体保护条件下所述固体磷酸二氢亚铁溶于水得溶液 B， 所述溶液 B与氢氧 化锂溶液充分反应生成胶体悬浊液 C ;
所述胶体悬浊液 C中加入氢氧化铁及热解碳源， 得悬浊液 D;
所述悬浊液 D喷雾干燥得到磷酸亚铁锂前躯体 E;
所述磷酸亚铁锂前躯体 E在弱还原气氛下进行两次焙烧， 第一次焙烧的温度为 450~500°C， 第二次焙烧的温度为 650~750°C， 得到含有亚铁直接合成的锂亚铁磷酸复盐 微晶和三价铁热解碳还原法锂亚铁磷酸复盐微晶及热解碳微晶均匀混合的锂离子电池正极 材料。
本发明的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法： 所述磷 酸溶液的浓度为 2.7~3.2摩尔 /升。
本发明的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法： 所述磷 酸溶液与所述铁屑反应的温度保持在 50~70°C。
本发明的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法： 所述固 体磷酸二氢亚铁、 所述氢氧化锂、 所述氢氧化铁、 热解碳的摩尔比为 (1.00): (2.00-2.05)： (0.96-1.00)： ( 0.9-1.8 ) 。
本发明的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法： 所述弱 还原气氛为 5~15%氢气和 95~85%氮气或氩气的混合气体或 100份氨分解气和 400~67份 氮气或氩气混合气体。
本发明的用铁屑， 磷酸， 氢氧化锂制备锂亚铁磷酸复盐正极材料的的新方法： 所述热 解碳源选自蔗糖、 葡萄糖、 柠檬酸、 淀粉和聚乙烯醇中的任一种或任几种。
附图说明
图 1为正极材料的 X-射线衍射图谱；
图 2为正极材料作正极活性物制备的 18650型 1200mAh圆柱锂离子电池 1. 0C充， 分 别 0. 2C, 1C , 5C放电曲线。
图 3 为正极材料作正极活性物制备的 18650 型 1200mAh 圆柱锂离子电池 1. 0C充， IOC放电循环曲线。
实施发明的最佳方式
实施例 1、
废铁屑： 电池行业生产电池元件的五金厂的废铁屑， 多孔废铁带材质如宝钢的 BDCK 或 SPCC: 其中所含杂质仅锰稍高 （Mn≤0.3%) ， 但锰是无害有益掺杂元素。
将废铁屑从顶部加料口装满立式反应器， 2.9摩尔 /升磷酸溶液从反应器下部进入直至 全浸铁屑接近上部反应液溢流口处， 2.9摩尔 /升磷酸溶液为市售 85%磷酸与水按照体积比 1： 4混合制成； 夹套加热， 使反应器下部温度保持在 50~60°C上部温度保持在 60~70°C以 促进反应， 当上部反应液的 pH值 =2.0， 比重 =1.30 时， 开始连续以适当速度加磷酸溶液， 此适当速度保证流出的反应液一直保持 pH值 =1.5， 比重 =1.30， 化学分析 Fe 1.1371mol/L,P04 3.0149mol/L; 反应液从上部反应液溢流口 （比液面低 10厘米） 经固液分 离器除去固体杂质后连续流入惰气保护储液罐中； 反应产生的氢气从顶部排气管通室外放 空， 管中冷凝水流回反应罐。
在惰性气体保护条件下将反应液从储液罐吸入真空蒸发器中真空蒸发浓缩， 并冷却结 晶， 离心甩干得固体磷酸二氢亚铁和母液， 分离出的母液用于配磷酸溶液循环使用； 在惰 性气体保护条件下固体磷酸二氢亚铁重新溶于水得溶液 B， 化学分析知 Fe:
P=1.4357mol/L: 2.9150mol/L， 溶液 B在搅拌下与所含磷酸二氢亚铁（以 P04计)两倍摩尔的 氢氧化锂溶液充分反应， 这里可能发生的反应有
2LiOH + Fe(H2P04)2→LiFeP04|+ LiH2P04+ 2H20 (1)
2LiOH + Fe(H2P04)2→FeHP04|+ Li2HP04+ 2H20 (2)
2LiOH + Fe(H2P04)2→Fe(OH)2|+ 2LiH2P04+ 2H20 (3)
体系处于胶体悬浊液 C状态，
胶体悬浊液 C在搅拌下按所含磷酸二氢亚铁每摩尔加入蔗糖 25.7g并完全溶解； 所述胶体悬浊液 C在搅拌下继续加入原所含磷酸二氢亚铁等摩尔的新制备的氢氧化铁 胶体得胶体悬浊液 D;
为方便仅按反应 （1 ) 讨论， 知加入的氢氧化铁恰好与 Li¾P04按高温碳还原法制成 LiFeP04:
2 LiH2P04 + 2Fe ( OH) 3 + C = 2 LiFeP04+ CO+5H20 (4)
以上固体磷酸二氢亚铁、 氢氧化锂、 氢氧化铁、 热解碳的摩尔比为 1.00: 2.00： 1.00： ( 0.5+0.4) ， 其中 0.5摩尔热解碳用于高温还原三价铁， 0.4摩尔热解碳保留产品中 作为产品的导电碳。 胶体悬浊液 D体相很均匀， 已知全部成分是等摩尔的 Li++Fe2+P04 3_ (直接合成 LiFeP04) 和等摩尔的 Li++Fe3++P04 3_ (合成 LiFeP04前三价铁先被热解碳还原为两价)均匀混合的多相 体系；
将悬浊液 D喷雾干燥得球形颗粒前躯体 E， 喷雾快速干燥使得前躯体 E中各球形颗粒的化学 成分保持了胶体悬浊液 D的均匀一致性。 在弱的还原气氛下 （100体积份氨分解气和 100 体积份氮气） 500°C焙烧 8小时， 700°C焙烧 15小时， 得到同一原料体系两种反应原理同时 进行形成 LiFeP04纳米微晶颗粒被热解碳均匀包覆并桥连的亚微米粒子， 从而得到振实密 度大比容量高产品均匀的锂亚铁磷酸复盐锂离子电池正极材料。 图 1 是锂亚铁磷酸复盐正 极材料 X-射线衍射图谱， 图 2和图 3为锂亚铁磷酸复盐正极材料电化学性能图。 由于同时 包含亚铁盐直接合成 LiFeP04和三价铁热碳还原合成 LiFeP04， 所以 XRD图谱与通常单一原 理制得的 LiFeP04不完全相同， 但由于 LiFeP04只有正交晶系一种晶型， 差别仅在于晶粒形 状和晶胞参数数值有差异， 表现为衍射最强几个峰的峰强次序有不同。
实施例 2、
废铁屑： 电池行业生产电池元件的五金厂的废铁屑， 多孔废铁带材质如宝钢的 BDCK 或 SPCC: 其中所含杂质仅锰稍高 （Mn≤0.3%) ， 但锰是无害有益掺杂元素。
将废铁屑从顶部加料口装满立式反应器， 2.7摩尔 /升磷酸溶液从反应器下部进入直至 全浸铁屑接近上部反应液溢流口处， 2.7摩尔 /升磷酸溶液为市售 85%磷酸与水按照体积比 1： 4.4混合制成； 夹套加热， 使反应器下部温度保持在 50~60°C上部温度保持在 60~70°C 以促进反应， 当上部反应液的 pH值 =2.5， 比重 =1.28时， 开始连续以适当速度加磷酸溶 液， 此适当速度保证流出的反应液一直保持 pH值 =2.5， 比重 =1.28， 化学分析 Fe
1.0975mol/L,PO4 2.8510mol/L; 反应液从上部反应液溢流口 （比液面低 10厘米） 经固液分 离器除去固体杂质后连续流入惰气保护储液罐中； 反应产生的氢气从顶部排气管通室外放 空， 管中冷凝水流回反应罐。
在惰性气体保护条件下将反应液从储液罐吸入真空蒸发器中真空蒸发浓缩， 并冷却结 晶， 离心甩干得固体磷酸二氢亚铁和母液， 分离出的母液用于配磷酸溶液循环使用； 在惰 性气体保护条件下固体磷酸二氢亚铁重新溶于水得溶液 B， 化学分析知 Fe:
P=1.2922mol/L: 2.6235mol/L, 溶液 B在搅拌下与所含磷酸二氢亚铁（以 P04计)两倍摩尔的 氢氧化锂溶液充分反应， 这里可能发生的反应有
2LiOH + Fe(H2P04)2→LiFeP04|+ LiH2P04+ 2H20 (1)
2LiOH + Fe(H2P04)2→FeHP04|+ Li2HP04+ 2H20 (2)
2LiOH + Fe(H2P04)2→Fe(OH)2|+ 2LiH2P04+ 2H20 (3) 体系处于胶体悬浊液 C状态；
胶体悬浊液 C在搅拌下按所含磷酸二氢亚铁每摩尔加入蔗糖 50g并完全溶解； 胶体悬浊液 C在搅拌下继续加入原所含磷酸二氢亚铁 0.98倍摩尔的新制备的氢氧化铁 胶体得胶体悬浊液 D;
为方便仅按反应 （1 ) 讨论， 知加入的氢氧化铁 (比理论值低 0.02摩尔是为了避免产 品出现铁氧化物杂质!)恰好与 Li¾P04按高温碳还原法制成 LiFeP04 :
2 LiH2P04 + 2Fe ( OH) 3 + C = 2 LiFeP04+ CO+5H20 (4)
以上固体磷酸二氢亚铁、 氢氧化锂、 氢氧化铁、 热解碳的摩尔比为 1.00: 2.00：
0.98： ( 0.5+1.3 ) ， 其中 0.5摩尔热解碳用于还原三价铁， 1.3摩尔热解碳保留产品中作为 产品的导电碳。
胶体悬浊液 D体相很均匀， 已知全部成分是等摩尔的 Li++Fe2+P04 3_(合成 LiFeP04)和等 摩尔的 Li++Fe3++P04 3_ (合成 LiFeP04,但三价铁先被热碳还原)均匀混合的多相体系； 将悬浊液 D喷雾干燥得球形颗粒前躯体 E， 喷雾快速干燥使得前躯体 E中各球形颗粒的化学 成分保持了胶体悬浊液 D的均匀一致性。 在弱的还原气氛下 [15% (体积百分含量） 氢气 +85%氮气 （体积百分含量） ]450°C焙烧 15小时， 680°C焙烧 20小时， 得到同一原料体系 两种反应原理同时进行形成 LiFeP04纳米微晶颗粒被热解碳均匀包覆并桥连的亚微米粒子， 从而得到产品均匀的锂亚铁磷酸复盐锂离子电池正极材料。
实施例 3、 废铁屑： 电池行业生产电池元件的五金厂的废铁屑， 多孔废铁带材质如宝 钢的 BDCK或 SPCC: 其中所含杂质仅锰稍高 （Mn≤0.3%) ， 但锰是无害有益掺杂元素。
将废铁屑从顶部加料口装满立式反应器， 3.2摩尔 /升磷酸溶液从反应器下部进入直至 全浸铁屑接近上部反应液溢流口处， 3.2摩尔 /升磷酸溶液为市售 85%磷酸与水按照体积比 1： 3.6混合制成； 夹套加热， 使反应器下部温度保持在 50~60°C上部温度保持在 60~70°C 以促进反应， 当上部反应液的 pH值 =1.5， 比重 =1.32 时， 开始连续以适当速度加磷酸溶 液， 此适当速度保证流出的反应液一直保持 pH值 =1.5， 比重 =1.32， 化学分析 Fe 1.1997mol/L,P04 3.1494mol/L; 反应液从上部反应液溢流口 （比液面低 10厘米） 经固液分 离器除去固体杂质后连续流入惰气保护储液罐中； 反应产生的氢气从顶部排气管通室外放 空， 管中冷凝水流回反应罐。
在惰性气体保护条件下将反应液从储液罐吸入真空蒸发器中真空蒸发浓缩， 并冷却结 晶， 离心甩干得固体磷酸二氢亚铁和母液， 分离出的母液用于配磷酸溶液循环使用； 在惰 性气体保护条件下固体磷酸二氢亚铁重新溶于水得溶液 B， 化学分析知 F e： P=1.4501mol/L: 2.9588mol/L， 溶液 B在搅拌下与所含磷酸二氢亚铁 (；以 P04计) 2.02倍摩尔 的氢氧化锂溶液充分反应， 这里可能发生的反应有
2LiOH + Fe(H2P04)2→LiFeP04|+ LiH2P04+ 2H20 (1)
2LiOH + Fe(H2P04)2→FeHP04|+ Li2HP04+ 2H20 (2)
2LiOH + Fe(H2P04)2→Fe(OH)2|+ 2LiH2P04+ 2H20 (3)
体系处于胶体悬浊液 C状态，
所述胶体悬浊液 C在搅拌下按所含磷酸二氢亚铁每摩尔加入蔗糖 32.8g并完全溶 解；
所述胶体悬浊液 C在搅拌下继续加入原所含磷酸二氢亚铁等摩尔的新制备的氢氧化铁 胶体得胶体悬浊液 D;
为方便仅按反应 （1 ) 讨论， 知加入的氢氧化铁恰好与 LiH2P04按高温碳还原法制成 LiFeP04:
2 LiH2P04 + 2Fe ( OH) 3 + C = 2 LiFeP04+ CO+5H20 (4)
以上固体磷酸二氢亚铁、 氢氧化锂、 氢氧化铁、 热解碳的摩尔比为 1.00: 2.04： 1.00： ( 0.5+0.65 ) ， 其中 0.5摩尔热解碳用于还原三价铁， 0.65摩尔热解碳保留产品中作 为产品的导电碳。
胶体悬浊液 D体相很均匀， 已知全部成分是等摩尔的 Li++Fe2+P04 3_(合成 LiFeP04)和等 摩尔的 Li++Fe3++P04 3_ (合成 LiFeP04,但三价铁先被热碳还原)均匀混合的多相体系；
将悬浊液 D喷雾干燥得球形颗粒前躯体 E， 喷雾快速干燥使得前躯体 E中各球形颗粒的 化学成分保持了胶体悬浊液 D的均匀一致性。 在弱的还原气氛下 [5%氢气 +95%氩气] 500°C 焙烧 10小时， 750°C焙烧 10小时， 得到同一原料体系两种反应原理同时进行形成 LiFeP04 纳米微晶颗粒被热解碳均匀包覆并桥连的亚微米粒子,从而得到产品均匀的锂亚铁磷酸复盐 锂离子电池正极材料。
工业实用性
本发明的用铁屑、 磷酸、 氢氧化锂制备锂亚铁磷酸复盐正极材料的新方法， 在同一原 料系统中属于湿法的溶液沉淀法锂亚铁磷酸复盐晶核和热碳还原法锂亚铁磷酸复盐晶核及 导电剂热解碳晶核， 同时或先后生成共同生长， 从而形成锂亚铁磷酸复盐微晶体被热解导 电碳包覆并桥连的均匀体， 有很好的导电性能， 电化学性能和加工性能。

Claims

权利要求
1、 一种用铁屑、 磷酸、 氢氧化锂制备锂亚铁磷酸复盐正极材料的新方法， 包括如下 步骤：
磷酸溶液与铁屑反应， 当反应液的 pH值^ 1.5， 比重 =1.25~1.32时， 收集反应液； 在惰性气体保护条件下所述反应液真空蒸发浓缩， 并冷却结晶得固体磷酸二氢亚铁和 母液；
在惰性气体保护条件下所述固体磷酸二氢亚铁溶于水得溶液 B， 所述溶液 B与氢氧化 锂溶液充分反应生成胶体悬浊液 C ;
所述胶体悬浊液 C中加入氢氧化铁及热解碳源， 得悬浊液 D;
所述悬浊液 D喷雾干燥得到磷酸亚铁锂前躯体 E;
所述磷酸亚铁锂前躯体 E在弱还原气氛下进行两次焙烧， 第一次焙烧的温度为 450~500°C， 第二次焙烧的温度为 650~750°C， 得到含有亚铁直接合成的锂亚铁磷酸复盐 微晶和三价铁热解碳还原法锂亚铁磷酸复盐微晶及热解碳微晶均匀混合的锂离子电池正极 材料。
2、 根据权利要求 1所述的方法， 其特征在于： 所述磷酸溶液的浓度为 2.7~3.2摩尔 / 升。
3、 根据权利要求 1或 2所述的方法， 其特征在于： 所述磷酸溶液与所述铁屑反应的 温度保持在 50~70°C。
4、 根据权利要求 3所述的方法， 其特征在于： 所述固体磷酸二氢亚铁、 所述氢氧化 锂、 所述氢氧化铁、 热解碳的摩尔比为（1.00): (2.00-2.05)： (0.96-1.00)： ( 0.9-1.8 ) 。
5、 根据权利要求 4所述的方法， 其特征在于： 所述弱还原气氛为 5~15%氢气和 95~85%氮气或氩气的混合气体或 100份氨分解气和 400~67份氮气或氩气的混合气体。
6、 根据权利要求 5所述的方法， 其特征在于： 所述热解碳源选自蔗糖、 葡萄糖、 柠 檬酸、 淀粉和聚乙烯醇中的任一种或任几种。
7、 权利要求 1至 6所述的方法制备的锂亚铁磷酸复盐正极材料， 为锂亚铁磷酸复盐 纳米微晶颗粒被热解碳均匀包覆并桥连的亚微米粒子粉末。
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CN101442117A (zh) * 2008-12-22 2009-05-27 上海电力学院 碳包覆磷酸铁锂的制备方法
CN101552331A (zh) * 2009-05-01 2009-10-07 徐州海天绿色能源科技有限公司 锂离子电池阳极材料磷酸亚铁锂的制备工艺

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CN110436432A (zh) * 2019-07-22 2019-11-12 贵州大学 一种纳米片状磷酸铁锂颗粒的低温制备方法
CN111326725A (zh) * 2020-03-05 2020-06-23 青海民族大学 一种锂离子有机正极材料、制备方法及应用
CN113086959A (zh) * 2021-02-26 2021-07-09 雅安锂盛新能企业管理中心(有限合伙) 高压实低温型磷酸铁锂材料、锂电池正极片及其制备方法
CN113086959B (zh) * 2021-02-26 2022-03-01 云南航开科技有限公司 高压实低温型磷酸铁锂材料、锂电池正极片及其制备方法

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