F掺杂 LiFePO4/C的固相合成及电化学性能

用廉价三价铁离子化合物为铁源,聚丙烯作还原剂和碳源,两步固相法合成F掺杂原位碳包覆LiFePO4正极材料.结果表明,合成产物具有完整的橄榄石型LiFePO4晶体结构,粉末形状近似球形,尺寸分布在50～200nm范围内,两步固相法更好地抑制了LiFePO4晶粒的长大.电化学测试结果表明,F掺杂提高了材料倍率放电性能,有效降低了材料电极的极化.在1C,2C,3C(C为150mA/g)充放电倍率下,LiFePO3.98F0.02/C的比容量分别为146mAh/g,137mAh/g,122mAh/g,1C循环55次后放电容量达到初始容量的99.3%.     

纳米锡铜复合氧化物的制备与电化学性能

采用沉淀法制备了作为锂离子电池负极材料的纳米锡铜复合氧化物粉末,并用X射线衍射对其结构进行了分析、透射电镜对其形貌进行了表征、充放电和循环伏安法等对其电化学性能进行了测试.结果表明:采用沉淀法可以制备出颗粒粒度较均匀、尺寸为90nm的锡铜复合氧化物;充放电30次到50次,锡铜复合氧化物放电容量由254.4mAh/g衰减到241.1mAh/g,放电容量保持率较高(95%),说明纳米锡铜复合氧化物具有较高的放电容量和良好的循环性能。     

碳热还原法制备Sn-C复合材料及其性能

用碳热还原法制备了Sn-C复合材料,通过XRD及SEM对其进行表征,并通过恒流充放电循环和慢速扫描循环伏安等方法对其电化学嵌脱锂性能做了研究.结果表明:SnO2碳热还原成金属Sn,晶粒尺寸约为42.8nm.该材料的首次嵌脱锂比容量分别可以达到1024.9和632.8mAh/g,循环15周以后的脱锂比容量为395.9mAh/g.     

ZnO/石墨烯纳米复合材料一步水热法制备及电化学性能研究

通过一步水热法成功制得氧化锌(ZnO)/石墨烯(GN)纳米复合材料。测试表明,ZnO/GN复合材料中纤锌矿结构的ZnO纳米棒直径100~200nm,均匀担载在GN网状结构中。ZnO/GN复合材料展现出了优异的电化学性能:在0.1A/g电流密度下的可逆放电比容量达1171mAh/g;0.4A/g充放电循环测试100次后,放电容量仍然维持在305mAh/g。     

LiFe_(1-x)Ni_xPO_4复合正极材料的制备及性能研究

采用两步固相原位烧结掺杂法制备了一系列镍掺杂的锂离子电池正极材料LiFe1-xNixPO4(x=0、0.03、0.05、0.07、0.10、0.15).Ni替代部分Fe,改变了LiFePO4的晶胞参教,细化了晶粒.充放电实验研究表明,低放电倍率(0.1C)时,LiFe0.095Ni0.05PO4的首次放电容量最大,为155mAh/g,较LiFePO4增加了22.8%;0.5C时,其容量为132mAh/g,较LiFePO4增加了14.7%;放电倍率增加为1C时,其容量也能达到122mAh/g,较LiFePO4增加了16.1%.适量掺杂Ni可提高LiFePO4的充放电比容量,改善其高倍率充放电性能.     

纳米氧化锰的制备及其电化学性能研究

用流变相-前驱物热分解法制备了纳米氧化锰粉末,用XRD、TEM和LPSA对粉末样品的组成、结构、粒度和形貌进行了表征.结果表明MnO和Mn3O4都属于立方晶系的球形粒子,平均粒径(d50)分别约为45.6nm和69.1nm.对MnO和Li2Mn2O4(由Mn3O4制备)的电化学性能研究表明,LiMn2O4具有较高的充放电容量和较好的循环性能,其首次放电容量为128mAh/g,经过十次充放电循环之后电容量仍有117.5mAh/g.而MnO的电化学性能欠佳.     

混料工艺对固相法合成LiNi0.5Mn1.5O4电化学性能的影响

以Li2CO3、MnO2、NiO为原料,用固相法合成了5V尖晶石结构的LiNin5Mn1.5O4正极材料;并对合成的样品进行XRD、SEM及电化学性能测试,研究不同混料工艺对固相法合成的高电压正极材料LiNi0.Mn1.5O4电化学性能的影响.结果表明:采用高速球磨混料方式易获得具有优异电化学性能的样品;球磨时间一定,随着球磨转速增加,合成样品的比容量呈先增加后减小的趋势:转速为350r/min时合成的LiNi0.5Mn1.5O4的电化学性能最佳,0.2C倍率下,首次放电比容量为125.3mAh/g,100次充放电循环后放电比容量为118.7 mAh/g,容量保持率为94.7％.     

氢化燃烧合成镁基储氢合金的电化学性能的研究

研究了氢化燃烧合成Mg2NiH4产物的电化学性能，并探索了机械球磨处理对产物电化学性能的影响。电化学测试表明，HCS产物不经任何处理，最大放电容量仅为45.13mAh／g；产物球磨后最大放电容量和高倍率放电能力得到提高，如产物经球磨1h后，最大放电容量增至259．24mAh／g，产物添加3％（质量分数）的石墨球磨5h，最大放电容量增加了10倍以上，达到481．50mAh/g。     

LiFePO4/C制备工艺的优化及其性能

用共沉淀法制备了球形NH4FePO4·H2O前驱体,再与Li2CO3和葡萄糖混合用固相焙烧法制备了LiFePO4/C正极材料.利用正交实验考察了焙烧温度、焙烧时间、球磨时间、x(Li):x(Fe)和葡萄糖用量等对材料首次放电比容量的影响,得到了最佳工艺条件.通过XRD、SEM、FTIR和恒流充放电测试仪等测试了材料的结构和电化学性能.所得材料在室温下电流密度为0.1、0.5和1C时首次放电比容量分别为147.6、136.7和122.3mAh/g,循环50次后容量分别为142.8、127.3和106.7mAh/g;在60℃下电流密度为0.5C时,其首次放电比容量为163.8mAh/g,循环性能良好.     

溶胶-凝胶法合成锂离子电池正极材料Li_(1+x)V_3O_8的初步探讨

采用溶胶-凝胶法合成锂离子电池正极材料Li1+xV3O8,并用X射线衍射、扫描电镜观察、充放电循环测试、循环伏安法扫描等,研究了Li1+xV3O8的物相结构、表面形貌以及电化学性能等,并探索了合成工艺条件对材料的电化学性能的影响。结果表明,温度为400℃时合成的Li1+xV3O8晶粒较为细小均匀,粒径大小相对较为均一,颗粒大小在0.5—1.0μm左右,这些小晶粒将有效地增加其比表面积,同时电化学性能较好,10mA/g的电流密度下首次放电容量为230 mAh/g,20次循环之后容量仍能达到180 mAh/g,循环性能较好。随着合成温度增高,首次放电容量减小,循环效率降低。     

Synthesization and characterization of FeS2 by mechanical alloying for Na/FeS2 cell

In this study, the FeS2 fine compound powders were synthesized by mechanical alloying (MA) for 15 hrs and stearic acid was added as PCA (Process Control Agent) to prevent the excessive cold welding and agglomeration. For the purpose of ulteriorly reducing the particle size to improve the contact areas between the active materials and conducting agents, the wet ball milling process was applied by employing normal hexane (C6H14) as the milling solvent. The mean particle size of FeS2 powders about 1.14 microm were obtained after 24 hrs wet ball milling. The powders were characterized by FE-SEM, XRD, TEM and EDS. To compare the influence of particle size on the properties of charge/discharge, the same electrolyte was employed for both tests by dissolving 1M NaCF3SO3 (sodium trifluoromethanesulfonate) in a liquid of TEGDME (tetraethylene glycol dimethylether). The first discharge capacity of Na/FeS2 cell made by dry ball milled powders was 440 mAh/g with a plateau potential at approximately 1.25 V versus Na/Na+ and 260 mAh/g at the 25th cycle at room temperature. Meanwhile, the initial discharge capacity of Na/FeS2 cell made by wet ball milled powders was 614 mAh/g with the same discharge plateau potential and retained 385 mAh/g at the 25th cycle. And the discharge capacity for wet milled system decreased continuously by repeated charge/discharge cycling in the first 20 cycles and has little change after 60 cycles, which means the good cycling properties, remaining half of its initial discharge capacity of 320 mAh/g even after 100 cycles.     

锂离子电池多孔硅/碳复合负极材料的研究

以商业化多晶硅粉为原料, 采用金属银催化剂诱导化学腐蚀的方法制得三维多孔硅材料。通过优化腐蚀条件, 得到孔径约为130 nm, 比表面为4.85 m²/g的多孔硅材料。将多孔硅和PAN溶液混合球磨并经高温烧结后在多孔硅表面包覆上一层致密的无定形碳膜, 从而制得多孔硅/碳复合材料作为锂离子电池的负极材料。3D多孔硅结构可以缓解电化学嵌/脱锂过程中材料的体积效应, 无定形碳膜层可有效改善复合材料的导电性能。电化学性能测试表明, 该多孔硅/碳复合负极材料电池在0.4 A/g的恒电流下, 首次放电容量3345 mAh/g, 首次循环库伦效率85.8%, 循环55次后容量仍保持有1645 mAh/g。并且在4 A/g的倍率下, 容量仍维持有1174 mAh/g。该方法原料成本低廉, 可规模化生产。     

锂离子电池正极材料LiMn_2O_4制备新工艺

采用球磨湿混和旋转合成相结合的新工艺来制备锂离子电池正极材料ＬｉＭｎ２Ｏ４,并对制备的材料进行了粒度、化学成分以及电化学性能测试．制备的ＬｉＭｎ２Ｏ４为正尖晶石结构,而且物质纯净．同一批次制备的材料化学成分均匀,粉末粒度分布范围窄,中粒径为１０．６７μｍ,首次充电容量为１２４ｍＡｈ／ｇ,放电容量为１１５ｍＡｈ／ｇ．循环次数达３０次时,放电容量还大于１００ｍＡｈ／ｇ,循环稳定性良好．球磨湿混工艺能将原料混合均匀,并能有效地使原料粒度细化而且粒度均匀．旋转合成工艺能使反应物和反应产物的温度均匀、粒度均匀、晶型结构与成分均匀．球磨湿混和旋转合成相结合的固相合成新工艺能制备出电化学性能性能良好的ＬｉＭｎ２Ｏ４     

锂离子电池用氧化锌/螺旋纳米碳纤维复合负极材料的制备及性能研究

以二水乙酸锌、一缩二乙二醇为原料,通过溶胶-凝胶法制备出氧化锌/螺旋纳米碳纤维(ZnO/HCNFs)复合材料。使用X射线衍射仪(XRD)、热重分析仪(TG)和扫描电子显微镜(SEM)等表征手段研究了ZnO/HCNFs复合材料的形貌结构,通过恒流充放电测试仪对材料的电化学性能进行测试。结果表明:ZnO颗粒均匀负载于HCNFs表面,粒径约为20~50nm。ZnO/HCNFs复合材料在200mA/g的电流密度下,其首次充放电比容量分别达到977mAh/g与788mAh/g,库仑效率为81%,经过100次循环以后,容量仍保持在501mAh/g,电化学性能较优异。     

Can the degree of crystallinity of ball-milled Mg2Ni intermetallic compound decide its electrochemical characteristics?

ABSTRACT

Nanostructured Mg₂Ni intermetallic compounds were synthesized by high-energy ball milling. Effect of milling time on structure and surface morphology of milled powders were studied using x-ray diffraction and scanning electron microscopy. Crystallite size and degree of crystallinity were confirmed by using transmission electron microscopy and selected area electron diffraction analysis. The particle size of 20 h milled electrode material is 230 nm and it reduced to 40 nm when the milling time is increased to 30 h. Further increase in the milling time reduces the particles size drastically and starts agglomerating. In order to understand the effect of milling time on reaction rates, differential thermal analysis was performed. Activation energy of the milled powders was calculated using Kissinger analysis. 30 h milled powder exhibits lower activation energy than others. Cyclic voltammetry, electrochemical impedance spectroscopy, and charge–discharge studies were done on the prepared electrode materials. 30 h milled electrode material delivers maximum discharge capacity with a superior capacity retention after 20 cycles at 20 mAg^?1.     

新型锂离子电池负极材料COFe3Sb12

用高能球磨方法制备出CoFe3Sb12合金粉末,研究了电化学性能。结果表明,CoFe3Sb12中的活性元素Sb可以与锂离子发生可逆电化学反应,其嵌锂产物为Li3Sb。CoFe3Sb12电极在20mA/g的电流密度下第一次可逆容量为396mAh/g。在材料中加入原子分数为50％的石墨（化学计量式为CoFe3Sb12-C16)后,以100mA/g进行充放电时,第一次可逆容量为380mAh/g。电极的循环寿命性能优良。     

Dependence of milling time on electrochemical properties of nano Si electrodes prepared by ball-milling

Morphology, crystallinity and electrochemical properties of Si powders fabricated by a mechanical milling process with milling time of 6-40 h were investigated by means of FESEM, XRD, Raman, TEM and cell test. Average size of Si powders was reduced to sub-micrometer scale after 10 h-milling and 40 nm-Si powders could be obtained at 48 h-milling. With increasing milling time, Si powders mostly changes from crystalline Si to amorphous one and the content of amorphous Si was increased. TEM result showed that a negligiable amount of crystalline Si remained even after 48 h-milling. Si electrode with 48 h-milled Si powders exhibited the best electrochemical properties in terms of capacity, efficiency and cycle performance: initial capacity of 3025 mAh g(-1), coulrombic efficiency of 79.4% and the capacity retention of 1000 mAh g(-1) (at 130 cycles). The good electrochemical properties of nano- and amorphous-Si are due to the high resistance against volume change and good reversibility of Li ion.     

SnSb-Mo三元合金的电化学性能及其改性

以机械合金法制备了SnSb-Mo合金,并用XRD、SEM和EDS对合金的成分、组成及形貌等进行了分析;对合金材料的嵌脱锂性能研究发现,合金材料在最初的几次循环较好,但在随后的循环过程中容量迅速下降,通过SEM和EIS的分析发现影响合金材料循环性能的主要原因是合金材料与Cu基体之间的电接触.经过热处理后具有良好的嵌脱锂性能,首次嵌锂容量高达589mAh/g,经过20次循环之后仍具有451mAh/g的容量.     

锂离子电池正极材料LiMn2O4制备新工艺

采用球磨湿混和旋转合成相结合的新工艺来制备锂离子的电池正极材料LiMn2O4,并对制备的材料进行了粒度,化学成分以及电化学性能测试,制备的LiMn2O4为正尖晶石结构,而且物质纯净,同一批次制备的材料化学成分均匀,粉末粒度分布范围窄,中粒径为10．67um,首次充电容量为124mAh/g,放电容量为115mAh/g,循环次数达30次时,放电容还大于100mAh/g,循环稳定性,球磨湿混工艺能将原料混合均匀,并能有效地使原料粒度细化而且粒度均匀,旋转合成工艺能使反应物和反应产物的温度均匀,粒度均匀,晶型结构与成分均匀,球磨湿混和旋转合成相结合的固相合成新工艺能制备出电化学性能性能良好的LiMn2O4。     

采用机械合金化方法制备Ti3Ni2合金的结构及电化学储氢性能

采用机械合金化方法用Ni粉和Ti粉得到了Ti3Ni2非晶合金。晶态Ti3Ni2合金初始容量比非晶合金要高。晶态合金初始容量可以达到240mAh／g。而非晶合金容量为173mAh／g。随着循环次数的增加，晶态合金放电容量呈线性下降趋势。而对于非晶电极材料来说，随着循环的进行，初始容量下降，但是达到一定循环次数以后，电极的放电容量达到基本稳定。