材料期刊网

Online Shape Dynamic Wrapping Angle Compensation Model of Cold Strip

YANG Li-po , YU Bing-qiang , YU Hua-xin

钢铁研究学报(英文版)

In specific condition, when wrapping angle of cold rolling strip covering surface of shape detecting roll dynamically changes, online radial compression of the shape detecting roll is changed too, and it seriously affects online shape detecting precision of cold strip. Based on the latest intelligent shape meter developed by Yanshan University, using PSO-BP neural network and actual working condition datum, the cold strip online dynamic wrapping angle compensation model is established, and successfully applied in 1250 mm 6-high cold mill, remarkable results are achieved. The error between calculated values and measured values of total tensions is within 3%.

关键词: cold rolling strip , shape detecting , wrapping angle , compensation , shape meter , cold mill

Mn掺杂Li3Fe2(PO4)3正极材料的制备与表征

宋翠环 , 孙军康 , 黄富强 , 刘战强 , 何品刚

功能材料

通过固相反应法合成出Li3+xFe2-xMnxn(Po4)3(x-0～O.1)、Li3Fel.ω5Mn0.05(PO4)3和Li2.95Fe1.ωMnoN.05(PO4)3正极材料.采用行星式球磨方法,均匀混合正极材料和导电乙炔黑以提高活性材料的电子导电率和降低颗粒尺寸.Mn掺杂的Li3Fe2(PO4)3样品的恒电流充放电测试和伏安循环测试(2～4V)发现,所有样品中Fe3+/Fe2+氧化还原电对均有两个稳定的充放电平台(2.8、2.7V)、Li3+,Fe2-xMnxII(PO4)3和Li3Fe1.95Mn0.05(PO4)3中Mn3+/Mn2+电对的充放平台位于3.5V左右.不同价态Mn的掺杂均可明显提高正极材料的电化学性能,其中Mn掺杂样品的电化学性能最好,其中Li3.05Fel.95MnⅡ0.05(PO4)3/C的C/20和C/2恒流放电比容量分别可达11O和66mAh/g.

关键词: 锂离子电池正极材料 , Li3Fe2(PO4)3 , Mn掺杂 , 循环伏安法

Studies of EPR parameters for Mn5+-doped Li3PO4 and Li3VO4 crystals

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The EPR parameters (zero-field splitting D and g factors g(vertical bar vertical bar), g(perpendicular to)) of Mn5+-doped Li3PO4 and Li3VO4 crystals are calculated from the complete high-order perturbation formulas based on a molecular orbital scheme for a 3d(2) ion in tetragonal MX4 clusters. These formulas include not only the contribution coming from crystal-field excitations, but also that arising from charge-transfer excitations (which is discarded in crystal field theory). The calculated results are in reasonable agreement with the observed values. The contributions to EPR parameters coming from the charge-transfer excitations are comparable with those arising from the crystal-field excitations. It appears that for a high valence state 3d(n) ion in crystals, the reasonable explanations of EPR parameters should take the contributions due to both crystal-field and charge-transfer excitations into account. (c) 2006 Elsevier B.V. All rights reserved.

关键词: electron paramagnetic resonance (EPR);crystal;and ligand-field theory;charge transfer mechanism;Mn5+;Li3PO4;Li3VO4;atomic screening constants;oxo coordination;phase-transition;scf;functions;laser action;complexes;pressure;forsterite;covalency;ions

Li3+xV2(PO4)3的合成及电化学性能研究

刘民忠 , 郭学益

稀有金属材料与工程

通过碳热还原法合成了化学计量比的Li3V2(PO4)3和富锂的锂离子电池正极材料Li3+xV2(PO4)3(x=0.02,0.04,0.05,0.06).利用XRD、SEM和电化学测试对Li3+xV2(PO4)3进行研究表明:所合成的试样均为单斜晶系结构,无杂相存在;SEM测试发现,掺锂可以明显改善Li3V2(PO4)3一次颗粒表面的结构和形貌;电化学性能测试表明,随着掺锂量的提高,试样的循环性能变好.通过研究发现,Li3.04V2(PO4)3具有较高的初始容量和良好的循环性能.

关键词: 锂离子电池 , Li3V2(PO4)3 , 掺杂 , 碳热还原

Li3Ni0.1V1.9(PO4)3的电化学性能研究

胡德鹏 , 鲁道荣 , 刘兴亮

金属功能材料

采用X射线衍射和电化学方法,研究了正极材料Li3 Ni0.1V19(PO4)3的结构和电化学性能.结果表明:Li3 Ni0.1V1.9(PO4)3具有单斜晶系结构.在室温下,以0.1C倍率放电时Li3Ni0.1V1.9(PO4)3的初始比容量为115mAh/g,从0.1C增加到0.4C经过60次循环后,比容量保持率为97.3％,而未掺杂镍的Li3V2(PO4)3,初始比容量为129 mAh/g,60次循环后,比容量保持率仅为69.7％.循环伏安和交流阻抗测试表明,Li3 Ni0.3V1.9(PO4)3有较低的极化电阻和较好的可逆性.

关键词: 锂离子电池 , Li3Ni0.1V1.9(PO4)3 , 结构 , 电化学性能

Electrochemical performance of the carbon coated Li3V2(PO4)(3) cathode material synthesized by a sol-gel method

Electrochimica Acta

A carbon coated Li3V2(PO4)(3) cathode material for lithium ion batteries was synthesized by a sol-gel method using V2O5, H2O2, NH4H2PO4, LiOH and citric acid as starting materials, and its physicochemical properties were investigated using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), transmission electron microscope (TEM), and electrochemical methods. The sample prepared displays a monoclinic structure with a space group of P2(1)/n, and its surface is covered with a rough and porous carbon layer. In the voltage range of 3.0-4.3 V, the Li3V2(PO4)(3) electrode displays a large reversible capacity, good rate capability and excellent cyclic stability at both 25 and 55 degrees C. The largest reversible capacity of 130 mAh g(-1) was obtained at 0.1C and 55 degrees C, nearly equivalent to the reversible cycling of two lithium ions per Li3V2(PO4)(3) formula unit (133 mAh g(-1)). It was found that the increase in total carbon content can improve the discharge performance of the Li3V2-(PO4)(3) electrode. In the voltage range of 3.0-4.8 V, the extraction and reinsertion of the third lithium ion in the carbon coated Li3V2(PO4)(3) host are almost reversible, exhibiting a reversible capacity of 177 mAh g(-1) and good cyclic performance. The reasons for the excellent electrochemical performance of the carbon coated Li3V2(PO4)(3) cathode material were also discussed. (c) 2007 Elsevier Ltd. All rights reserved.

关键词: Li3V2(PO4)(3);sol-gel method;carbon surface layer;electrochemical;performance;lithium-ion batteries;carbothermal reduction method;state synthesis;routine;vanadium fluorophosphate;electrode materials;phosphates;lifepo4;li3fe2(po4)(3);composites;insertion

锂离子电池正极材料Li₃V₂(PO₄)₃的制备及性能研究

应皆荣 , 高剑 , 姜长印 , 李维 , 唐昌平

无机材料学报 doi:10.3724/SP.J.1077.2006.01097

单斜结构的Li₃V₂(PO₄)₃是很有前途的聚阴离子型锂离子电池正极材料. 将一定配比的LiOH H₂O、V₂O₅、H₃PO₄和蔗糖(C₁₂H₂₂O₁₁)通过球磨均匀混合, 在氮气保护下于800℃焙烧16h, 通过碳热还原合成了Li₃V₂(PO₄)₃. 用X射线衍射和扫描电镜分析对材料的结构和形貌进行了表征. 充放电测试表明, 在电压范围为3.0~4.3V和3.0~4.8V时, Li₃V₂(PO₄)₃正极材料具有较高的比容量、优良的循环性能和倍率特性. 在电压范围为1.5~4.8V时, Li₃V₂(PO₄)₃正极材料具有很高的比容量, 但循环性能较差.

关键词: 锂离子电池 , cathode material , Li3V2(PO4)3

锂离子电池正极材料Li3V2(PO4)3的制备及性能研究

应皆荣 , 高剑 , 姜长印 , 李维 , 唐昌平

无机材料学报 doi:10.3321/j.issn:1000-324X.2006.05.012

单斜结构的Li3V2(PO4)3是很有前途的聚阴离子型锂离子电池正极材料.将一定配比的LiOH·H2O、V2O5、H3PO4和蔗糖(C12H22O11)通过球磨均匀混合,在氮气保护下于800℃焙烧16h,通过碳热还原合成了Li3V2(PO4)3.用X射线衍射和扫描电镜分析对材料的结构和形貌进行了表征.充放电测试表明,在电压范围为3.0～4.3V和3.0～4.8V时,Li3V2(PO4)3正极材料具有较高的比容量、优良的循环性能和倍率特性.在电压范围为1.5～4.8V时,Li3V2(PO4)3正极材料具有很高的比容量,但循环性能较差.

关键词: 锂离子电池 , 正极材料 , Li3V2(PO4)3

溶胶-凝胶法制备Li3V2 (PO4)3粉体的形貌控制研究

刘建科 , 韩晨 , 夏傲 , 于克锐 , 陈永佳

人工晶体学报

以LiOH·H2O,NH4VO3,H3PO4和柠檬酸为原料,十二烷基苯磺酸钠(SDBS)为表面活性剂,采用溶胶凝胶法实现了Li3V2(PO4)3粉体的制备.添加不同剂量的十二烷基苯磺酸钠(SDBS)探究其对Li3V2(PO4)3粉体物相形貌的控制作用,采用热分析、X射线衍射和场发射扫描电子显微镜对其晶型结构,形貌特征进行表征,从而研究Li3V2(PO4)3的合成温度及十二烷基苯磺酸钠(SDBS)加入量对粉体物相形貌的影响.结果表明,用溶胶凝胶法制备合成了单斜结构Li3V2(PO4)3粉体.SDBS的加入对样品的晶粒尺寸和表面形貌有一定的影响.

关键词: Li3V2(PO4)3 , 溶胶凝胶 , 表面活性剂

Na^＋掺杂对Li3V2（PO4）3/C晶体结构及性能的影响

龙云飞 , 李媚琳 , 杨克迪 , 葛利 , 吕小艳 , 文衍宣

功能材料

利用一步碳热还原法制备了Li3-xNaxV2（PO4）3/C（x=0、0.01、0.02、0.03、0.05、0.08、0.10、0.15）复合正极材料,并用X射线衍射、扫描电镜、红外光谱、循环伏安法、电化学阻抗谱和恒电流充放电技术研究了掺杂对材料结构、微观形貌、充放电性能和Li＋脱出嵌入过程的影响。研究表明掺杂少量Na＋不影响材料Li3V2（PO4）3的基本结构,但可在Li3V2（PO4）3中形成电子缺陷,提高晶体内部原子的无序化程度,降低极化和电荷转移电阻,从而改善材料的电化学性能。与Li3V2（PO4）3/C相比,Li2.98 Na0.02 V2（PO4）3/C在倍率为15C下的第50次放电容量提高12.1mAh/g,具有较好的倍率性能和循环性能。

关键词: 锂离子电池 , 正极材料 , Li3V2(PO4)3/C , 碳热还原技术 , Na+掺杂