CN103367722B - A kind of preparation method of charcoal coated LiFePO 4 for lithium ion batteries nanocomposite - Google Patents
A kind of preparation method of charcoal coated LiFePO 4 for lithium ion batteries nanocomposite Download PDFInfo
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 13
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 13
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 239000002114 nanocomposite Substances 0.000 title claims description 11
- 229910010707 LiFePO 4 Inorganic materials 0.000 title claims description 10
- 239000003610 charcoal Substances 0.000 title claims 6
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims abstract description 19
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 18
- 239000000725 suspension Substances 0.000 claims abstract description 18
- 238000003756 stirring Methods 0.000 claims abstract description 15
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims abstract description 12
- 239000002131 composite material Substances 0.000 claims abstract description 11
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 9
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 8
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000011574 phosphorus Substances 0.000 claims abstract description 6
- 239000011790 ferrous sulphate Substances 0.000 claims abstract description 5
- 235000003891 ferrous sulphate Nutrition 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 4
- 238000006243 chemical reaction Methods 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 10
- 238000000576 coating method Methods 0.000 claims description 9
- 229910001386 lithium phosphate Inorganic materials 0.000 claims description 9
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 claims description 9
- 239000011248 coating agent Substances 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000011331 needle coke Substances 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 239000011294 coal tar pitch Substances 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 4
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 claims description 4
- 239000002243 precursor Substances 0.000 claims description 4
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 3
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 3
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 3
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 3
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 3
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 239000002006 petroleum coke Substances 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- -1 polytetrafluoroethylene Polymers 0.000 claims description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims 1
- 229910052493 LiFePO4 Inorganic materials 0.000 claims 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 claims 1
- 239000002270 dispersing agent Substances 0.000 claims 1
- 239000007789 gas Substances 0.000 claims 1
- 238000007789 sealing Methods 0.000 claims 1
- 239000002904 solvent Substances 0.000 claims 1
- 238000005406 washing Methods 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 26
- 229910052799 carbon Inorganic materials 0.000 abstract description 26
- 238000000034 method Methods 0.000 abstract description 15
- 230000015572 biosynthetic process Effects 0.000 abstract description 6
- 238000003786 synthesis reaction Methods 0.000 abstract description 6
- 238000003763 carbonization Methods 0.000 abstract description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract description 3
- 238000004729 solvothermal method Methods 0.000 abstract description 3
- 229910052742 iron Inorganic materials 0.000 abstract description 2
- 239000002086 nanomaterial Substances 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 18
- 239000011295 pitch Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 6
- 239000010406 cathode material Substances 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000003760 magnetic stirring Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229960002089 ferrous chloride Drugs 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 238000001694 spray drying Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 230000005536 Jahn Teller effect Effects 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000007970 homogeneous dispersion Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
Classifications
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- 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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Abstract
本发明公开一种炭包覆磷酸铁锂纳米级复合材料的制备方法。该方法的过程包括：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。本发明具有如下优点：本发明的合成工艺简单，工艺条件易于控制且对环境无污染；所制得的炭包覆磷酸铁锂纳米材料取向好、缺陷少、结晶度高，作为锂离子电池正极材料应用时具有很好的大电流充放电性能和稳定的循环性能。The invention discloses a preparation method of carbon-coated lithium iron phosphate nanoscale composite material. The process of the method includes: preparing the amphiphilic carbon material and ethylene glycol into a suspension, adding a lithium source including lithium hydroxide, a phosphorus source including phosphoric acid, and an iron source including ferrous sulfate to the suspension for stirring and reacting, It is then placed in a high-temperature reactor for solvothermal reaction, and placed in a carbonization furnace for heat treatment to obtain a carbon-coated lithium iron phosphate composite material with a particle size of 30-100 nm. The invention has the following advantages: the synthesis process of the invention is simple, the process conditions are easy to control and has no pollution to the environment; the prepared carbon-coated lithium iron phosphate nanomaterial has good orientation, few defects, and high crystallinity, and can be used as the positive electrode of lithium ion batteries When the material is applied, it has good high-current charge-discharge performance and stable cycle performance.
Description
技术领域 technical field
本发明涉及一种炭包覆磷酸铁锂纳米级复合材料的制备方法，属于锂离子电池正极材料技术领域。 The invention relates to a preparation method of a carbon-coated lithium iron phosphate nanoscale composite material, which belongs to the technical field of cathode materials for lithium-ion batteries.
背景技术 Background technique
锂离子电池用正极材料主要是锂与过渡金属元素形成的嵌入式化合物，研究比较多的有LiCoO2、LiNiO2、LiMn2O4、LiFePO4等。但Co系资源有限，价格昂贵且毒性较大，环境污染严重；Ni系合成条件苛刻；Mn 系由于Jahn-Teller 效应导致锂离子电池循环性能差。1997年， Padhi等将LiFePO4引入锂离子电池。由于LiFePO4具有170 mAh/g的理论容量，3.2～3.5 V(vs. Li+/Li)的平台电位，良好的循环稳定性和安全性，环境友好，原料来源广泛，成为应用前景很好的锂离子电池正极材料。但是LiFePO4的电子电导率低（10-10～10-9 S/cm）以及锂离子扩散速率慢（1.8×10-14 cm2/s），限制了LiFePO4材料的电化学性能。目前研究者主要从纳米化和形貌控制，导电相表面包覆，不等价离子掺杂等方面来改善LiFePO4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；导电相（如碳）表面包覆可以改善电子在材料界面之间的传输。 The cathode materials for lithium-ion batteries are mainly embedded compounds formed by lithium and transition metal elements. LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , and LiFePO 4 have been studied more. However, Co-based resources are limited, expensive and highly toxic, and cause serious environmental pollution; Ni-based synthesis conditions are harsh; Mn-based lithium-ion batteries have poor cycle performance due to the Jahn-Teller effect. In 1997, Padhi et al. introduced LiFePO 4 into lithium-ion batteries. Because LiFePO 4 has a theoretical capacity of 170 mAh/g, a plateau potential of 3.2 to 3.5 V (vs. Li + /Li), good cycle stability and safety, environmental friendliness, and a wide range of raw material sources, it has become a promising candidate for application. Lithium-ion battery cathode material. However, the low electronic conductivity of LiFePO 4 (10 -10 ~ 10 -9 S/cm) and the slow diffusion rate of lithium ions (1.8×10 -14 cm 2 /s) limit the electrochemical performance of LiFePO 4 materials. At present, researchers mainly improve the electrochemical performance of LiFePO 4 from the aspects of nanonization and morphology control, surface coating of conductive phase, and unequal ion doping. Among them, nanonization can shorten the time required for Li + and electrons to diffuse from the bulk phase to the electrolyte, and increase the Li + diffusion rate; the surface coating of conductive phases (such as carbon) can improve the transport of electrons between material interfaces.
目前关于纳米磷酸铁锂的研究较多，其中专利CN101944601A制备均匀炭包覆纳米磷酸铁锂的方法，采用均相结晶法制得粒径为20～100 nm的磷酸铁锂前驱体，再与纳米级炭进行溶液中充分混合，烧结得到均匀炭包覆的纳米磷酸铁锂。炭包覆属于合成后的包覆，增加了制备工序。专利CN102623701A制备低温型纳米磷酸铁锂材料的方法，先将锂源、铁源、磷源等湿法混合，高能超细磨处理，喷雾干燥，过筛；再预烧结进行二次高能超细磨处理，喷雾干燥，过筛；最后经过气流粉碎，两次高温热处理得到晶粒尺寸为60～70 nm的磷酸铁锂材料。工艺流程复杂。 At present, there are many studies on nano-lithium iron phosphate, among which the patent CN101944601A prepares a method for uniform carbon-coated nano-lithium iron phosphate, adopts a homogeneous crystallization method to obtain a lithium iron phosphate precursor with a particle size of 20-100 nm, and then combines it with nano-scale The carbon is fully mixed in the solution, and sintered to obtain nanometer lithium iron phosphate coated with uniform carbon. Carbon coating belongs to the coating after synthesis, which increases the preparation process. Patent CN102623701A The method for preparing low-temperature nano-lithium iron phosphate material, first wet mixing lithium source, iron source, phosphorus source, etc., high-energy ultra-fine grinding treatment, spray drying, sieving; and then pre-sintering for secondary high-energy ultra-fine grinding treatment, spray drying, and sieving; finally, jet crushing and two high-temperature heat treatments to obtain lithium iron phosphate materials with a grain size of 60-70 nm. The process is complicated.
溶剂热的相对低温、等压、溶液条件，有利于极少缺陷、取向好、完美的晶体的生长，产物结晶度高，而且易于控制产物晶体的粒度，在无机微纳米材料的合成中得到了广泛应用。原位炭包覆通过位阻效应可明显细化颗粒，不但可以有效控制产物的形貌和晶粒尺寸，避免LiFePO4团聚生成大粒径，从而缩短Li+扩散距离，增加Li+扩散速率；还可以提高颗粒之间的电子导电性，使不同颗粒之间的电荷传递能够及时完成，可实现对合成产物的均匀包覆。 The relatively low temperature, equal pressure, and solution conditions of solvothermal are conducive to the growth of few defects, good orientation, and perfect crystals. The product has high crystallinity, and it is easy to control the particle size of the product crystal. It has been obtained in the synthesis of inorganic micro-nano materials. widely used. In-situ carbon coating can significantly refine the particles through the steric hindrance effect, not only can effectively control the morphology and grain size of the product, but also avoid the agglomeration of LiFePO 4 to form a large particle size, thereby shortening the Li + diffusion distance and increasing the Li + diffusion rate; It can also improve the electronic conductivity between particles, so that the charge transfer between different particles can be completed in time, and the uniform coating of the synthetic product can be realized.
发明内容 Contents of the invention
本发明的目的是提供一种炭包覆磷酸铁锂纳米级复合材料的制备方法，该炭包覆磷酸铁锂纳米级复合材料具有良好的电化学性能，其方法制备过程简单，环境友好，能耗低。 The purpose of the present invention is to provide a preparation method of a carbon-coated lithium iron phosphate nanocomposite material, which has good electrochemical properties, and the preparation process of the method is simple, environmentally friendly, and can low consumption.
本发明是通过以下技术方案实现的，一种炭包覆磷酸铁锂纳米级复合材料的制备方法，所述的炭包覆磷酸铁锂复合材料，该炭包覆磷酸铁锂复合材料的粒径为30～100 nm，其中，炭包覆层厚度为2～3 nm，炭包覆层与磷酸铁锂核的质量比为（0.1~0.01）：（0.9~0.99），其特征在于包括以下步骤： The present invention is achieved through the following technical scheme, a method for preparing a carbon-coated lithium iron phosphate nanocomposite material, the carbon-coated lithium iron phosphate composite material, the particle size of the carbon-coated lithium iron phosphate composite material 30-100 nm, wherein, the thickness of the carbon coating layer is 2-3 nm, and the mass ratio of the carbon coating layer to the lithium iron phosphate core is (0.1-0.01): (0.9-0.99), which is characterized in that it includes the following steps :
（1）将两亲性炭材料与乙二醇混合，超声分散0.3～2 h，配制成质量浓度为1.5～6 mg/ml 的悬浮液；其中，两亲性炭材料的前驱体原料包括：煤沥青、石油焦、针状焦； (1) Mix the amphiphilic carbon material with ethylene glycol, ultrasonically disperse for 0.3-2 h, and prepare a suspension with a mass concentration of 1.5-6 mg/ml; among them, the precursor raw materials of the amphiphilic carbon material include: Coal tar pitch, petroleum coke, needle coke;
（2）以氢氧化锂、醋酸锂为锂源，以磷酸、磷酸二氢铵、磷酸氢二铵为磷源，搅拌下将锂源加入步骤（1）悬浮液中，使反应体系中Li的含量为0.03～3 mol/L，按Li与P的摩尔比为3:1，在反应体系中缓慢加入磷源，进行搅拌反应0.5～2 h，制得磷酸锂悬浊液，在制得的悬浊液中加入与磷酸锂等物质的量的亚铁盐，进行搅拌反应0.5～2 h。所述的亚铁盐为硫酸亚铁、氯化亚铁； (2) Use lithium hydroxide and lithium acetate as the lithium source, phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate as the phosphorus source, and add the lithium source to the suspension in step (1) under stirring, so that the Li in the reaction system The content is 0.03-3 mol/L, according to the molar ratio of Li and P of 3:1, slowly add phosphorus source into the reaction system, and carry out stirring reaction for 0.5-2 h to obtain lithium phosphate suspension. Add ferrous salt in the amount of lithium phosphate and other substances to the suspension, and carry out stirring reaction for 0.5-2 h. Described ferrous salt is ferrous sulfate, ferrous chloride;
（3）将步骤（2）配制的均相分散液转移到聚四氟乙烯反应釜中，密封，将反应釜置于110～220 ℃的恒温烘箱中，进行溶剂热反应5～24 h，自然冷却至室温后将产物用去离子水和无水乙醇进行洗涤至无杂离子存在，然后在60～120 ℃下真空干燥3～24 h，得到两亲性炭材料包覆的磷酸铁锂复合材料； (3) Transfer the homogeneous dispersion prepared in step (2) to a polytetrafluoroethylene reactor, seal it, place the reactor in a constant temperature oven at 110-220 °C, and perform solvothermal reaction for 5-24 h, and naturally After cooling to room temperature, the product was washed with deionized water and absolute ethanol until no foreign ions existed, and then vacuum-dried at 60-120 °C for 3-24 h to obtain a lithium iron phosphate composite material coated with an amphiphilic carbon material ;
（4）将步骤（3）制得的两亲性炭材料包覆的磷酸铁锂复合材料置于炭化炉中，在氮气或氩气的保护下，以1～10 ℃/min的升温速率升至500～800 ℃，恒温热处理1～15 h，然后自然冷却至室温，获得炭包覆磷酸铁锂纳米级复合材料。 (4) Place the lithium iron phosphate composite material coated with the amphiphilic carbon material prepared in step (3) in a carbonization furnace, and under the protection of nitrogen or argon, heat up at a rate of 1-10 °C/min. to 500-800 °C, constant temperature heat treatment for 1-15 h, and then naturally cooled to room temperature to obtain carbon-coated lithium iron phosphate nanocomposites.
本发明具有如下优点：本发明采用溶剂热法，使得在溶液环境中离子间可以均匀混合，有利于极少缺陷、取向好、完美的晶体的生长，产物结晶度高；本发明的合成工艺简单，工艺条件易于控制，并且原料无毒、无污染、廉价易得；采用原位包覆的方法，使炭包覆与前驱体合成一并完成，炭包覆层可以大大改善材料的电子导电能力；本方法可控合成颗粒尺寸为30～100 nm的磷酸铁锂；在作为锂离子电池正极材料应用时具有很好的大电流充放电性能和稳定的循环性能。 The present invention has the following advantages: the present invention adopts the solvothermal method, so that the ions can be uniformly mixed in the solution environment, which is conducive to the growth of crystals with few defects, good orientation and perfect crystallinity, and the product has high crystallinity; the synthesis process of the present invention is simple , the process conditions are easy to control, and the raw materials are non-toxic, non-polluting, cheap and easy to obtain; using the in-situ coating method, the carbon coating and the precursor synthesis are completed together, and the carbon coating layer can greatly improve the electronic conductivity of the material ; This method can controlly synthesize lithium iron phosphate with a particle size of 30-100 nm; it has good high-current charge-discharge performance and stable cycle performance when applied as a lithium-ion battery cathode material.
附图说明 Description of drawings
图1是本发明实施例1制备的炭包覆磷酸铁锂纳米级复合材料的XRD图谱。 Fig. 1 is an XRD spectrum of the carbon-coated lithium iron phosphate nanocomposite material prepared in Example 1 of the present invention.
图2是本发明实施例1制备的炭包覆磷酸铁锂纳米级复合材料的SEM照片。 Fig. 2 is an SEM photo of the carbon-coated lithium iron phosphate nanocomposite material prepared in Example 1 of the present invention.
图3是本发明实施例1制备的炭包覆磷酸铁锂纳米级复合材料的HRTEM照片。 Fig. 3 is an HRTEM photo of the carbon-coated lithium iron phosphate nanocomposite material prepared in Example 1 of the present invention.
图4是本发明实施例1制备的炭包覆磷酸铁锂纳米级复合材料作为锂离子电池正极材料的倍率充放电曲线图。 Fig. 4 is a rate charge and discharge curve diagram of the carbon-coated lithium iron phosphate nanocomposite material prepared in Example 1 of the present invention as the positive electrode material of the lithium ion battery.
图5是本发明实施例1制备的炭包覆磷酸铁锂纳米级复合材料作为锂离子电池正极材料的循环性能曲线图。 Fig. 5 is a graph of the cycle performance of the carbon-coated lithium iron phosphate nanocomposite material prepared in Example 1 of the present invention as the positive electrode material of the lithium ion battery.
具体实施方式 Detailed ways
实施例1 Example 1
1. 以中温煤焦油沥青为原料，采用酸氧化法制备两亲性炭材料，具体制备过程如下：将沥青使用球磨机粉碎过筛，取粒径小于150 μm的沥青颗粒作为原料。将50 ml混酸（以质量浓度为65%的浓硝酸和质量浓度为98%的浓硫酸体积比为3:7配制）加热到80 ℃，以300 r/min的搅拌速率搅拌，加入10 g中温煤沥青，反应3 h，将反应物倒入500 mL去离子水中终止反应，采用减压过滤装置过滤，所得滤饼用去离子水洗涤至中性；将得到的固体物质加入到500 mL浓度1 mol/L的NaOH溶液中，在80 ℃下以300 r/min的转速搅拌1 h，减压过滤，在此过程中保持溶液的pH值始终大于12；收集滤液，在得到的滤液中滴加1 mol/L的HCl，调节其pH值至2，此时有沉淀生成；离心分离，将得到的沉淀物用去离子水洗涤至pH值为3，在烘箱中100 ℃烘干10 h，即得沥青基两亲性炭材料。 1. Using medium-temperature coal tar pitch as raw material, the amphiphilic carbon material is prepared by acid oxidation method. The specific preparation process is as follows: the pitch is crushed and sieved by a ball mill, and pitch particles with a particle size of less than 150 μm are used as raw material. Heat 50 ml of mixed acid (prepared with concentrated nitric acid with a mass concentration of 65% and concentrated sulfuric acid with a mass concentration of 98% at a volume ratio of 3:7) to 80 °C, stir at a stirring speed of 300 r/min, and add 10 g of medium-temperature Coal tar pitch, reacted for 3 h, poured the reactant into 500 mL deionized water to terminate the reaction, filtered it with a vacuum filter device, and washed the obtained filter cake with deionized water until neutral; mol/L NaOH solution, stirred for 1 h at 80 °C at a speed of 300 r/min, filtered under reduced pressure, and kept the pH value of the solution greater than 12 during the process; collected the filtrate, and added dropwise to the obtained filtrate 1 mol/L HCl, adjust its pH value to 2, at this time, a precipitate is formed; centrifuge, wash the obtained precipitate with deionized water until the pH value is 3, and dry it in an oven at 100 °C for 10 h, that is A pitch-based amphiphilic carbon material was obtained.
2. 将0.1896 g步骤1制得的沥青基两亲性炭材料加入到60 ml乙二醇中，超声分散30 min。加入1.5120 g氢氧化锂粉末，，磁力搅拌条件下滴加质量浓度为85%的磷酸1.3835 g至悬浮液中，继续搅拌30 min，得到磷酸锂悬浊液。在上述悬浊液中加入3.336 g硫酸亚铁，继续搅拌30 min，将最终的悬浊液加入到75 ml反应釜中并密封，放入烘箱中加热至180 ℃，保温10 h，自然冷却后离心，并用去离子水和无水乙醇洗涤至无SO4 2-杂离子存在，80 ℃真空干燥12 h。取烘干后的产物置于高温炭化炉中，在氮气保护下以2 ℃ /min的升温速率升温至650 ℃，恒温3 h后自然冷却至室温，即得到产品。 2. Add 0.1896 g of the pitch-based amphiphilic carbon material prepared in step 1 into 60 ml of ethylene glycol, and disperse ultrasonically for 30 min. Add 1.5120 g of lithium hydroxide powder, and dropwise add 1.3835 g of phosphoric acid with a mass concentration of 85% into the suspension under magnetic stirring conditions, and continue stirring for 30 min to obtain a lithium phosphate suspension. Add 3.336 g of ferrous sulfate to the above suspension, continue stirring for 30 min, add the final suspension into a 75 ml reaction kettle and seal it, put it in an oven and heat it to 180 °C, keep it warm for 10 h, and cool it naturally Centrifuge, wash with deionized water and absolute ethanol until no SO 4 2- heteroions exist, and dry in vacuum at 80°C for 12 h. The dried product was placed in a high-temperature carbonization furnace, and the temperature was raised to 650 °C at a rate of 2 °C/min under the protection of nitrogen, and then cooled to room temperature naturally after constant temperature for 3 h to obtain the product.
实施例1制得的炭包覆磷酸铁锂复合材料的XRD图谱如图1所示，本材料的峰位与标准卡片（PDF 81-1173）的峰位完全一致，可证明本材料为磷酸铁锂纯相。从图2的SEM照片得所制得的产品颗粒尺寸约30 nm，尺寸分布均匀。并且从图3的HRTEM照片中可以看出产品颗粒表面均匀包覆一层2～3 nm厚的炭层。组装成电池测得材料在放电电流密度1C、10C、30C下容量分别达138.8 mAh/g、106.7 mAh/g、77.9 mAh/g。 The XRD pattern of the carbon-coated lithium iron phosphate composite material prepared in Example 1 is shown in Figure 1. The peak position of this material is completely consistent with the peak position of the standard card (PDF 81-1173), which can prove that this material is iron phosphate Lithium pure phase. From the SEM photo of Figure 2, the particle size of the prepared product is about 30 nm, and the size distribution is uniform. And from the HRTEM photo in Figure 3, it can be seen that the surface of the product particles is evenly coated with a 2-3 nm thick carbon layer. Assembled into a battery, the measured capacity of the material reached 138.8 mAh/g, 106.7 mAh/g, and 77.9 mAh/g at discharge current densities of 1C, 10C, and 30C, respectively.
实施例2 Example 2
制备方法与实施例1基本相同，不同之处在于步骤2中加入0.0948 g沥青基两亲性炭材料。所得产品颗粒平均尺寸约100 nm。 The preparation method was basically the same as in Example 1, except that 0.0948 g of pitch-based amphiphilic carbon material was added in step 2. The resulting product has an average particle size of about 100 nm.
实施例3 Example 3
制备方法与实施例1基本相同，不同之处在于步骤1中初始原料为针状焦，混酸用量为100 ml，制备针状焦基两亲性炭材料。步骤2中用针状焦基两亲性炭材料代替沥青基两亲性炭材料。所得产品颗粒平均尺寸约100 nm。 The preparation method was basically the same as in Example 1, except that the initial raw material in step 1 was needle coke, and the amount of mixed acid was 100 ml to prepare needle coke-based amphiphilic carbon materials. In step 2, the pitch-based amphiphilic carbon material is replaced by the needle coke-based amphiphilic carbon material. The resulting product has an average particle size of about 100 nm.
实施例4 Example 4
1. 与实施例1的步骤1相同。 1. Same as step 1 of embodiment 1.
2. 将0.2844 g步骤1制得的沥青基两亲性炭材料加入到60 ml乙二醇中，超声分散1 h。加入5.5080 g醋酸锂粉末，磁力搅拌条件下加入2.0700 g磷酸二氢铵，继续搅拌1 h，得到磷酸锂悬浊液。在上述悬浊液中加入5.0040 g硫酸亚铁，继续搅拌30 min，将最终的悬浊液加入到75 ml反应釜中并密封，放入烘箱中加热至170 ℃，保温6 h，自然冷却后离心，并用去离子水和无水乙醇洗涤至无SO4 2-杂离子存在，90 ℃真空干燥12 h。取烘干后的产物置于高温炭化炉中，在氮气保护下以5 ℃ /min的升温速率升温至700 ℃，恒温3 h后自然冷却至室温，即得到产品。所得产品颗粒尺寸约50 nm，尺寸分布均匀。 2. Add 0.2844 g of the pitch-based amphiphilic carbon material prepared in step 1 into 60 ml of ethylene glycol, and disperse ultrasonically for 1 h. Add 5.5080 g of lithium acetate powder, add 2.0700 g of ammonium dihydrogen phosphate under magnetic stirring conditions, and continue stirring for 1 h to obtain a lithium phosphate suspension. Add 5.0040 g of ferrous sulfate to the above suspension, continue stirring for 30 min, add the final suspension into a 75 ml reaction kettle and seal it, put it in an oven and heat it to 170 °C, keep it warm for 6 h, and cool it naturally Centrifuge, wash with deionized water and absolute ethanol until no SO 4 2- heteroions exist, and dry under vacuum at 90°C for 12 h. The dried product was placed in a high-temperature carbonization furnace, and the temperature was raised to 700 °C at a rate of 5 °C/min under the protection of nitrogen, and then cooled naturally to room temperature after constant temperature for 3 h to obtain the product. The particle size of the obtained product is about 50 nm, and the size distribution is uniform.
实施例5 Example 5
1. 与实施例1的步骤1相同。 1. Same as step 1 of embodiment 1.
2. 将0.1517 g步骤1制得的沥青基两亲性炭材料加入到60 ml乙二醇中，超声分散30 min。加入3.6720 g醋酸锂粉末，磁力搅拌条件下加入1.5720 g磷酸氢二铵，继续搅拌1 h，得到磷酸锂悬浊液。在上述悬浊液中加入2.3880 g氯化亚铁，继续搅拌30 min，将最终的悬浊液加入到75 ml反应釜中并密封，放入烘箱中加热至200 ℃，保温8 h，自然冷却后离心，并用去离子水和无水乙醇洗涤至无Cl-杂离子存在，80 ℃真空干燥12 h。取烘干后的产物置于高温炭化炉中，在氮气保护下以1 ℃ /min的升温速率升温至650 ℃，恒温6 h后自然冷却至室温，即得到产品。所得产品颗粒尺寸约45 nm，尺寸分布均匀。 2. Add 0.1517 g of the pitch-based amphiphilic carbon material prepared in step 1 into 60 ml of ethylene glycol, and disperse ultrasonically for 30 min. Add 3.6720 g of lithium acetate powder, add 1.5720 g of diammonium hydrogen phosphate under magnetic stirring conditions, and continue stirring for 1 h to obtain a lithium phosphate suspension. Add 2.3880 g of ferrous chloride to the above suspension, continue stirring for 30 min, add the final suspension into a 75 ml reaction kettle and seal it, put it in an oven and heat it to 200 °C, keep it warm for 8 h, and let it cool naturally Then centrifuge, wash with deionized water and absolute ethanol until no Cl- heteroions exist, and dry in vacuum at 80 °C for 12 h. The dried product was placed in a high-temperature carbonization furnace, and the temperature was raised to 650 °C at a rate of 1 °C/min under the protection of nitrogen, and then cooled naturally to room temperature after a constant temperature of 6 h to obtain the product. The particle size of the obtained product is about 45 nm, and the size distribution is uniform.
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