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51.
Influence of Ti^4+ doping on electrochemical properties of LiFePO4/C cathode material for lithium-ion batteries 总被引:2,自引:0,他引:2
To improve the performance of LiFePO4, single phase Li1-4xTixFePO4/C (x=0, 0.005, 0.010, 0.015) cathodes were synthesized by solid-state method. A certain content of glucose was used as carbon precursor and content of carbon in every final product was about 3.5%. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy observations(SEM), charge/discharge test, carbon analysis and electrochemical impedance spectroscopy(EIS). The results indicate that the prepared samples have ordered olivine structure and doping of the low concentration Ti~(4+) does not affect the structure of the samples. The electrochemical capabilities evaluated by charge-discharge test show that the sample with 1% Ti~(4+) (molar fraction) has good electrochemical performance delivering about an initial specific capacity of 146.7 mA·h/g at 0.3C rate. Electrochemical impedance spectroscopy measurement results show that the charge transfer resistance of the sample could be decreased greatly by doping an appropriate amount Ti~(4+). 相似文献
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In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepared Fe2P2O7, Li2CO3 and glucose as raw materials, pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃ in an argon atmosphere. X-ray diffractometry and scanning electron microscopy(SEM) were employed to characterize the as-prepared Fe2P2O7, LiFePO4 and LiFePO4/C. The as-prepared Fe2P2O7 crystallizes in the Cl space group and belongs to β-Fe2P2O7 for crystal phase. The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0 μm. During the Li^+ ion chemical intercalation, radical P2O7^4- is disrupted into two PO4^3- ions in the presence of O^2-, thus providing a feasible technique to dispose this poor dissolvable pyrophosphate. LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA·h/g, respectively. 相似文献
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对常用的两层电极(活性材料层|集电极)进行改进,提出一种新颖的夹心状三层电极(导电材料层|活性材料层|集电极)以提高 LiFePO4/C 的电化学性能。充放电测试表明:相比两层电极,三层电极中 LiFePO4/C 表现出更优的倍率性能。循环伏安和电化学阻抗测试表明:相比两层电极,三层电极中LiFePO4/C材料中的Fe3+/Fe2+氧化还原电对表现出更快的氧化还原速度。更好的可逆性能以及更低的电荷转移阻抗。在三层电极中,活性材料层表层中与LiFePO4/C颗粒尺寸相当的孔洞被粒径小得多的乙炔黑微粒填充,形成LiFePO4/C颗粒间的导电连接,为暴露在电解液主体LiFePO4/C颗粒中的LiFePO4晶体提供更多运输电子到达或离开的路径。 相似文献
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以Na2SiO3.9H2O和FeCl2.4H2O为原料,采用低热固相反应获得了分散均匀的β-FeOOH/SiO2前驱体;再以Li2CO3为锂源、聚乙烯醇和超导电炭黑为复合碳源,通过微波辅助固相法合成了Li2FeSiO4/C材料.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和恒电流充放电测试等方法对材料的结构、微观形貌及电化学性能进行表征.650℃下微波处理12 min可获得结晶好、晶粒细小均匀的Li2FeSiO4/C材料;在选用的微波合成体系下,超导碳和聚乙烯醇热分解的无定形碳不仅利于合成反应的顺利进行,而且提高了Li2FeSiO4的整体导电性能.制备的复合正极材料在60℃下0.05C倍率首次放电容量为129.6 mAh/g,0.5C倍率下为107.5 mAh/g,0.5C下15次循环后保持为104.8 mAh/g,具有较好的放电比容量和良好的循环稳定性能.结果表明,微波辅助固相合成工艺是制备Li2FeSiO4/C复合材料的一种很有前景的方法. 相似文献
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56.
以铬铁合金为原料,以草酸作为沉淀剂来沉淀铬铁合金浸出液中的Fe,在沉淀Fe的过程中铬铁合金浸出液中微量的Mn、Ni、Co等多种元素被同时沉淀于草酸亚铁中,可以得到掺杂的草酸亚铁Fe(1-x)MxC2O4(M=Ni、Mn、Co等),然后制备得到复合掺杂磷酸铁锂LiFe(1-x)MxPO4/C(M=Ni、Mn、Co等),并对其进行了形貌及电化学性能的测试。电化学测试结果表明,该材料具有良好的电化学性能,0.1 C下的放电容量达到162 mAh/g,1 C下循环50次容量保持率达到98.2%。 相似文献
57.
高碳铬铁制备氢氧化铬的研究 总被引:1,自引:0,他引:1
以高碳铬铁合金粉为原料,经过硫酸高温搅拌浸出,通过草酸除铁法除铁后得到含杂质量低的硫酸铬溶液,然后用碳酸氢铵调节硫酸铬溶液pH得到氢氧化铬沉淀.研究了溶液中铬离子浓度、反应温度、pH以及各种添加剂对铬(Ⅲ)的沉淀回收率及氢氧化铬沉淀过滤性的影响.通过实验得到溶液中铬(Ⅲ)回收的最佳条件:反应温度为85 ℃、溶液中铬(Ⅲ)质量浓度为10 g/L、pH=6.5、搅拌强度为200 r/min.在此条件下铬(Ⅲ)的回收率高达99%,并且氢氧化铬沉淀具有较好的过滤性, 滤液中铬质量浓度达0.001 5 g/L,完全可达到国家排放标准,具有一定的工业实用价值. 相似文献
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层状LiNi1/3Co1/3Mn1/3O2正极材料合成及电化学性能 总被引:1,自引:0,他引:1
首次提出以碳酸盐为沉淀剂,采用共沉淀法制备Ni1/3Co1/3Mn1/3CO3前驱体,再和锂源混合高温固相合成了锂离子蓄电池层状LiNi1/3Co1/3Mn1/3O2正极材料。采用X射线衍射(XRD)和电子扫描电镜(SEM)对Ni1/3Co1/3Mn1/3CO3前驱体和LiNi1/3Co1/3Mn1/3O2正极材料的结构及形貌进行了表征,SEM测试表明LiNi1/3Co1/3Mn1/3O2的形貌近似为球形,且颗粒分布均匀。并对其进行了充放电性能和循环伏安研究,实验结果表明:LiNi1/3Co1/3Mn1/3O2在25℃、2.5"4.6V电压范围,0.1C倍率下,首次放电比容量达182.97mAh/g。 相似文献
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介绍了以β-Ni(OH)2、CoSO4、MnSO4和LiOH·H2O为原料,在β-Ni(OH)2表面同时包覆Co、Mn合成锂离子电池正极材料LiNi09Mn0.03Co0.07O2的方法。XRD测试结果表明:样品为α-NaFeO2结构;SEM和EDS结果表明:Co、Mn均包覆在β-Ni(OH)2表面上,且包覆均匀、致密。合成的材料在电流密度为30mA/g下,第二次循环放电容量为194mAh/g,50次循环后容量仍保持为189mAh/g,材料循环性能稳定。 相似文献