机械活化氧化法制备锰酸锂及其性能研究

以高纯金属锰粉和碳酸锂为原料,通过机械活化氧化法合成了尖晶石LiMn2O4材料。采用X射线衍射(XRD)和扫描电镜(SEM)对LiMn2O4样品结构及形貌进行表征,用充放电测试和交流阻抗技术对LiMn2O4样品进行电化学性能研究。结果表明,所制备的LiMn2O4具有完整的尖晶石型结构,且颗粒形貌规整,颗粒大小均匀。所制备的LiMn2O4材料室温(25℃)在3.0~4.3V电压范围,在0.1C倍率下首次放电比容量为125.8mAh/g;2C首次放电容量为120.1mAh/g,300次循环后放电容量保持103.9mAh/g,容量保持率为86.51%。且样品具有较好的高温性能和较小的阻抗。     

综合利用铬铁合金制备复合掺杂磷酸铁锂的研究

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%。     

Effect of cooling modes on microstructure and electrochemical performance of LiFePO4

LiFePO4 was prepared by heating the pre-decomposed precursor mixtures sealed in vacuum quartz-tube. Three kinds of cooling modes including nature cooling, air quenching, and water quenching were applied to comparing the effects of cooling modes on the microstructure and electrochemical characteristics of the material. The results indicate that the water quenching mode can control overgrowth of the grain size of final product and improve its electrochemical performance compared with nature cooling mode and air quenching mode. The sample synthesized by using water quenching mode is of the highest reversible discharge specific capacity and the best cyclic electrochemical performance, demonstrating the first discharge capacity of 138.1 mA·h/g at 0.1C rate and the total loss of capacity of 3.11% after 20 cycles.     

Preparation and property of spinel LiMn2O4 material by co-doping anti-electricity ions

1 Introduction At present, LiCoO2 is almost the only cathode material of Li-ion batteries, which can be used in large-scale commercialization, because such material possesses high specific capacity, ease of preparation, high discharging flat and favorable…     

Surface modification of LiCo0. 05Mn1.95O4 cathode by coating with SiO2-TiO2 composite

1　INTRODUCTIONSincethefirstcommercializationbySonyCorpo rationintheearly 1990s ,thelithium ionbattery(LIB)hasbecomeamajorproducttodominatethemarketforsmallrechargeablebatteries .Further more ,Li ionbatteriesareexpectedtobeusedasalarge scaleenergystoragedeviceforelectricvehices(EV ) [1] .ThoughvarioustypesofcathodematerialssuchasLiCoO2 ,LiNiO2 ,LiMn2 O4 ,andsubstitutedtran sitionmetaloxidesarecurrentlyusedincommercial izedLi ionbatteries[2 ,3] ,LiCoO2 inthesecathodematerialsismost…     

天然石墨中的嵌/脱锂离子过程

研究了锂离子在天然石墨中的嵌入 /脱出过程 ,以及电流密度对锂离子嵌入石墨过程的影响。非现场XRD结果显示 ,石墨的层间距随锂的嵌入与脱出发生先膨胀后收缩复原的变化 ;SEM结果显示 ,小电流密度下石墨表面的SEI膜较致密、均匀 ,而大电流密度下的则疏松、不均一 ;恒电流充放电测试结果显示 ,在相同的嵌锂电位下锂与微晶石墨和鳞片石墨所形成的层间化合物 (Li GICs)不完全相同 ;合理的充放电制度有利于小幅度改善材料的大电流充放电性能。     

Electrochemical performances and structure characteristic of LiMn2O4-xYx（Y=F, Cl, Br） compounds

Spinel LiMn2 O4-x Yx (Y=F, Cl, Br) compounds were prepared by solid-state reaction and the electrochemically galvanostatic charge-discharge cycles were performed using as-prepared compounds as cathode material. The influence of halogens on their lattice constants and the relation of electrochemical properties and their lattice constants were investigated. It is concluded that when the lattice constants are smaller than that of LiMn2O4, the reversible capacity fade is suppressed and the initial capacity sacrifice is observed. When the content of fluorine is 0.05, the lattice constant of LiMn2O3.95 F0.05 is larger than that of LiMn2O4, the initial capacity is improved. An efficient method was found to control the lattice constants of LiMn2O4 through the addition of halogen, and to improve the electrochemical performance of LiMn2O4. The LiMn2O3.95 F0.05 shows excellent electrochemical charge-discharge performance, with high initial capacity of 143 mAh/g and nearly no capacity loss after 116 cycles.     

Influence of Ti^4＋ doping on electrochemical properties of LiFePO4/C cathode material for lithium-ion batteries

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+).     

Industrial testing of property-modified prebaked carbon anode for aluminum electrolysis

1　INTRODUCTIONInaluminumelectrolysis process ,thequantitygradeofcarbonanoderestrictsnotonlytheimprove mentofproductiontechniques ,butalsotheadvance mentofproductiontargets.Formany years ,largenumberofresearchesweredonetoimprovethephysi cal,chemicalandelectrochemicalperformanceoftheanodeinordertoenhancecurrentefficiency ,reduceenergyconsumption ,decrease productioncostandcleancircumstanceofaluminum plantanditssur roundingarea .Recently ,manylaboratoryresearchresultsweresuccessfullyappliedf…     

金刚石表面化学镀Ni—W—P及高温下WC的生成机制

采用化学镀方法对金刚石表面镀覆Ｎｉ－Ｗ－Ｐ非晶态合金，镀层通过高温热处理后，经Ｘ射线衍射分析，证实了金刚石表面镀层有碳化钨生成；通过热力学分析，提出了碳化钨的生成机制。