FePO_4包覆的LiMn_(1.5)Ni_(0.5)O_4/Li_(3.9)Na_(0.1)Ti_5O_(12)全电池性能

分别采用溶胶凝胶法和高温固相法合成了Fe PO4包覆的Li Mn1.5Ni0.5O4正极材料和Li3.9Na0.1Ti5O12负极材料,并组装了Li Mn1.5Ni0.5O4/Li3.9Na0.1Ti5O12(LMNO/LNTO)全电池,采用充放电测试、循环伏安(CV)和电化学阻抗(EIS)研究了Fe PO4包覆对Li Mn1.5Ni0.5O4/Li4Ti5O12全电池电化学性能的影响。结果表明,Fe PO4的包覆抑制了Li Mn1.5Ni0.5O4高温合成时Mn3+的产生,有利于锂离子的可逆脱嵌。Fe PO4包覆的Li Mn1.5Ni0.5O4/Li3.9Na0.1Ti5O12(FP-LMNO/LNTO)比LMNO/LTO全电池具有更高的放电容量、循环性能、库仑效率和能量密度。FP-LMNO/LNTO全电池更适合作为动力锂离子电池。     

FePO_4包覆改善LiNi_(0.5)Mn_(1.5)O_4正极材料高温循环性能

采用喷雾干燥法制备Li Ni0.5Mn1.5O4正极材料,通过沉淀法在Li Ni0.5Mn1.5O4正极材料表面包覆Fe PO4以改善Li Ni0.5Mn1.5O4材料的高温循环性能。制备了质量分数1%Fe PO4、3%Fe PO4、5%Fe PO4三种不同包覆比例的Li Ni0.5Mn1.5O4/Fe PO4材料,电化学测试结果显示质量分数1%Fe PO4包覆效果最好。X射线衍射光谱法(XRD)数据表明,Fe PO4表面包覆处理并没有影响Li Ni0.5Mn1.5O4的晶型,材料仍为尖晶石结构。电化学性能测试表明,质量分数1%Fe PO4包覆材料的高温下循环稳定性得到显著的提升,其充放电100次后比容量为120 m Ah/g,为初始比容量的96.7%,远高于未包覆材料的89.99%的容量保持率。扫描电子显微镜法(SEM)观察显示,质量分数1%Fe PO4包覆的材料中Li Ni0.5Mn1.5O4颗粒被Fe PO4均匀包覆。ICP数据表明,Fe PO4的包覆减少了Li Ni0.5Mn1.5O4材料在高温循环时锰元素和镍元素的溶解,从而提高材料的循环稳定性。     

溶胶凝胶法制备锂离子电池正极材料LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2的研究

综述了溶胶凝胶法制备锂离子电池三元正极材料Li Ni1/3Mn1/3Co1/3O2的研究,讨论了三元材料的结构特性,着重从添加有机络合剂、掺杂、包覆改性以及模板辅助等方面探讨对Li Ni1/3Mn1/3Co1/3O2材料电化学性能的影响,并分析三元材料目前存在的问题和未来应用的前景。     

富锂正极材料Li[Li_(0.2)Mn_(0.4)Fe_(0.4)]O_2的表面包覆改性

用共沉淀法合成了富锂正极材料Li[Li0.2Mn0.4Fe0.3Al0.1]O2,并对其表面进行AlPO4包覆。采用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、电化学测试等方法对样品进行表征。结果表明,与Li[Li0.2Mn0.4Fe0.4]O2相比,包覆改性后的Li[Li0.2Mn0.4Fe0.4]O2具有较好的电化学性能,其初始放电容量未明显降低,而循环寿命大大提高,经50次充放电循环后,容量衰减量在10%左右。     

磷酸铁包覆锂离子电池正极材料LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

为了提高锂离子电池三元正极材料Li Ni1/3Co1/3Mn1/3O2的电化学性能,采用共沉淀法在Li Ni1/3Co1/3Mn1/3O2的表面包覆Fe PO4。采用SEM、XRD、EDS及电化学性能测试对制备的包覆材料的形貌、结构及电化学性能进行表征,探索包覆量对其高倍率循环性能的影响。实验结果表明:通过表面包覆有效地抑制了正极材料与电解液的相互作用,改善了材料的高倍率循环性能。当包覆量为2%、1 C电流循环时,首次充放电比容量分别为166.3、143.8 m Ah/g,库仑效率为86.5%;循环100次后,容量保持率为90.8%。     

LiFeO_2包覆锂离子正极材料Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2制备及性能表征

采用溶胶-凝胶工艺在Li[Li0.2Mn0.54Ni0.13Co0.13]O2表面包覆LiFeO2,并用扫描电镜(SEM),X-射线衍射(XRD),EIS和恒电流充放电等方法研究了不同包覆量的LiFeO2包覆对Li[Li0.2Mn0.54Ni0.13Co0.13]O2结构和电化学性能的影响。XRD、SEM实验数据表明,该材料具有层状α-NaFeO2结构,包覆后材料结构没有变化,表面覆盖上一层纳米级别的颗粒。电化学性能测试结果表明,质量分数1%LiFeO2包覆能显著改善Li[Li0.2Mn0.54Ni0.13Co0.13]O2材料在高截止电压(4.8 V)下的循环性能和倍率性能,EIS研究结果显示其界面阻抗明显减小,电子电导率得到提高,从而提高电化学性能。     

锂离子电池层状正极材料LiMO2的改性研究

综述了锂离子电池层状正极材料LiMO2M(=Co、Ni、Mn)的结构、性能及目前存在的问题,介绍了近几年来LiM O2M(=Co、Ni、Mn)的改性研究进展,并着重探讨了元素掺杂和表面包覆改性对上述材料的结构和电化学性能的影响,对掺杂离子的特点、作用进行了小结。     

Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2/BiPO_4的高循环性能

用固相法合成富锂材料Li[Li0.2Mn0.54Ni0.13Co0.13]O2,通过包覆磷酸铋(Bi PO4)对材料进行表面改性,以提高循环稳定性。XRD、SEM及TEM测试结果表明,包覆材料Li[Li0.2Mn0.54Ni0.13Co0.13]O2/Bi PO4的结构与Li[Li0.2Mn0.54Ni0.13Co0.13]O2相比没有发生变化,Bi PO4均匀地包覆在材料表面,包覆层厚度约为10 nm。在2.0~4.8 V充放电,当电流为0.1 C时,制备的Li[Li0.2Mn0.54Ni0.13Co0.13]O2/Bi PO4的首次库仑效率从Li[Li0.2Mn0.54Ni0.13Co0.13]O2的75%提高到83%,以0.2 C循环100次,放电比容量保持在249 m Ah/g。     

锂离子电池Li_(1.1)Ni_(0.35)Mn_(0.55)O_2正极材料的低温放电效率研究

通过共沉淀结合高温固相法合成Li1.1Ni0.35Mn0.55O2正极材料,在材料组分不变的情况下,通过改善合成条件,研究材料自身低温放电效率的变化,在此基础上,对其进行掺杂Co改性。采用X射线衍射光谱法(XRD)和扫描电子显微镜法(SEM)表征Li1.1Ni0.35Mn0.55O2正极材料的微观结构和颗粒形貌。通过电化学性能测试表征材料的低温放电效率。结果表明:在烧结温度900℃,保温时间12 h下的材料阳离子排列有序度最好,低温放电效率为52.67%;同时离子掺杂有利于低温性能的改善,掺杂少量Co有利于提高低温放电效率(64.56%)。     

流变相法合成ZnO包覆的尖晶石LiNi0.5Mn1.5O4

以CH3COOLi、Ni(CH3COO)2和Mn(CH3COO)2为原料,用流变相法合成了正极材料ZnO包覆的Li Ni0.5Mn1.5O4。XRD测试表明:该材料为尖晶石结构。电化学性能测试表明:包覆ZnO后,Li Ni0.5Mn1.5O4在3.5～4.9 V以0.1C充放电的首次放电比容量为137.68 mAh/g,第30次循环的放电比容量为133.78 mAh/g,循环稳定性得到了改善。     

高温固相法合成LiNi0.25Co0.5Mn0.25O2及其结构性能研究

采用高温固相法合成了层状LiNi0.25Co0.5Mn0.25O2正极材料。通过X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)以及恒电流充放电测试,研究了LiNi0.25Co0.5Mn0.25O2材料的结构、形貌以及电化学性能。实验结果表明950℃7 h合成的样品具有最好的电化学性能,在0.1 C时2.5～4.3 V间,其首次充放电比容量分别为166.3 mAh/g和150 mAh/g,循环10周容量保持96%;XRD精修结果表明Li层中只有1.1%的位置被Ni所占据。     

固相法合成Li_(0.25)Na_(0.75)MnO_2的性能

以Li2CO3、Na2CO3、Mn3O4为原料,采用固相法合成了锂离子电池正极材料Li0.25Na0.75Mn O2。在高温(800℃)下合成的材料具有P2结构、P63/mmc空间群;在较低温度(500~700℃)下合成的材料为具有一定层错的混合结构。在600℃下合成的材料在2.0~4.8 V充放电,电流为0.1 C时的首次放电比容量为213.3 m Ah/g,电流为0.2 C时循环34次,容量保持率为83%。材料在充放电过程中会发生结构转变,形成与Li2Mn O3结构类似、但更稳定的新相。     

Glassy ferromagnetism in La0.75Sr0.25-xKxCoO3 polycrystalline perovskite cobaltites

In this paper, the structural and magnetic properties of La_0.75Sr_0.25-xK_xCoO₃ (0≤x≤0.15) powder samples are reported. X-ray diffraction analysis using Rietveld refinement show that all our samples crystallize in the rhombohedral structure with \( R\overline{3}c \) space group. At low temperatures, with increasing K amount, the samples change from ferromagnetic like behavior (x?=?0, 0.05 and 0.1) to spin glass one (x?=?0.15). The ferromagnetic-paramagnetic transition temperature decreases with increasing K amount from 235K (x?=?0) to 200K (x?=?0.1). In the paramagnetic phase, all our synthesized samples obey the Curie-Weiss law. In the vicinity of T_C, the magnetic entropy change |ΔS _M | for La_0.75Sr_0.2K_0.05CoO₃ sample reached maximum values of 0.47Jkg/K and 2.27Jkg/K under magnetic field variation in the range 1T and 7T, respectively. The magnetization hysteresis loops demonstrate a weakening the ferromagnetism with increasing K content.     

0.25级精密压力表和0.5级压力变送器的测量不确定度评定

一切测量结果都不可避免地具有不确定度。根据CNAL/AC01∶2005《检测和校准实验室认可准则》的要求,校准实验室对所有校准项目的测量不确定度都应进行评定,必须给出每个测量结果的不确定度。文章以0.25级精密压力表和0.5级压力变送器为例,对其测量不确定度的评定进行阐述。     

2．25Cr-1Mo-0．25V低合金耐热钢的相变行为

研究了冷却速率对2．25Cr-1Mo-0．25V低合金耐热钢种相变行为的影响。发现钢的相变点Ac1,和Ac3分别为795℃和890℃,当冷却速率为0．1～200℃／s时,连续冷却相变曲线主要分为3个部分,即铁素体加珠光体转变区、贝氏体转变区及马氏体转变区;试验材料的维氏硬度随冷却速率的增加而逐渐递增。     

La0.75Mg0.25Ni3.1-xCo0.4Alx合金的微观结构及性能

通过铸造工艺制备La0.75Mg0.25Ni3.1-xCo0.4Alx(x=0、0.05、0.10、0.15和0.20)贮氢合金,并对x=0.10的合金进行退火处理。分析了Al替代量x和退火温度对合金的影响。合金均含有(La,Mg)Ni3相(PuNi3结构)、LaNi5相和一定量的LaNi2相。铸态合金中LaNi5相的量由x=0时的14.28%增至x=0.20时的24.07%。Al的替代提高了合金的循环稳定性,但比容量由x=0时的398.7mAh/g降至x=0.20时的350.1mAh/g。合金均有优良的活化性能。在900℃下的退火处理,使合金的容量和循环稳定性得到提高。     

微粒溶胶-凝胶法合成LiNi0.75 Co0.25O2及表征

通过LiOH·H2O、Ni(OAc)2·4H2O和Co(OAc)2·4H2O在水和乙醇混合溶剂中形成微粒溶胶-凝胶来合成LiNi0.75Co0.25O2.TG-DTA、XRD和充放电实验结果表明:当原料n(Li):n(Ni):n(Co)=1.05:0.75:0.25时,形成的凝胶经300℃预处理、600℃顸烧之后,再在氧气氛中700℃焙烧24h,所得产物的层状晶体结构最完整,其首次放电容量为176.6mAh/g;经过10次循环之后,放电容量还有170.1 mAh/g,容量衰减3.7%,显示出较高的初始放电容量及良好的循环性能.     

Novel Damage Curing Technology on One-Mask Etched Ferroelectric Capacitor for Beyond 0.25 μm FRAM

In order to manufacture high-density ferroelectric random access memory (FRAM) device, it is required to develop one mask capacitor etching technology, because it can provide greatly reduced cell size. However, as the capacitor size shrinks further, the influence of etching damage on the ferroelectric properties becomes much serious due to the high ratio of perimeter/area for patterned capacitor. Since undesired polymeric etch byproducts were formed on sidewall of the edge cell capacitors in 32 Mb FRAM with 0.25 μm design rule, we developed novel post-etch curing technology using O₂ plasma treatment with wet cleaning process. After the post-etch curing treatment, the hysteresis loops of block edge cells were almost identical to those of block center cells, which results in improving the relative 2Pr value as ratio of edge cells/center cells from 33% to 98%. In conclusion, novel curing technology was successfully developed for one mask etching damaged ferroelectric capacitor using O₂ plasma treatment with wet cleaning process, resulting in high wafer yield.     

Mg掺杂对LiNi_(0.6)Co_(0.15)Mn_(0.25)O_2电化学性能的影响

以氢氧化钠为沉淀剂,氨水为络合剂,通过氢氧化物共沉淀法制得前驱体,然后高温煅烧,合成锂离子电池正极材料Li(Ni_(0.6)Co_(0.15)Mn_(0.25))_(1-x)Mg_xO_2(x=0、0.01、0.02、0.03和0.04)。通过XRD、循环伏安、电化学阻抗谱(EIS)和恒流充放电等测试,研究Mg掺杂对材料性能的影响。适量的Mg掺杂可降低材料阳离子混排度,提高材料的循环性能及倍率性能。Li(Ni_(0.6)Co_(0.15)Mn_(0.25))_(0.98)Mg_(0.02)O_2的电化学性能较好,以0.1 C在2.7~4.3 V循环,首次放电比容量高达190.9 mAh/g;1.0 C循环30次的容量保持率为90.07%。     

Advanced Encapsulating Barrier Layer Technology for 0.25 μm 1T1C 32Mbit FRAM

As the capacitor size greatly decreases from 1.44 in 4Mb to 0.44 w m 2 in 32Mb FRAM, the hydrogen-damage is severely increased, thus giving rise to the difficulty in protecting the ferroelectric capacitor from the hydrogen attack by using conventional encapsulating barrier layers (EBL). Therefore, it is strongly required to reduce the hydrogen-induced degradation of very small ferroelectric capacitor during the backend integration process. In this paper, we developed double EBL technology by covering whole ferroelectric capacitors again after the Cap-EBL process. The Al 2 O 3 ILD-EBL layer was prepared again after depositing inter-layer dielectrics (ILD) layer, thus eliminating further hydrogen damage during inter-metal dielectrics (IMD) process. Using the double EBL technology, the fully integrated ferroelectric capacitor for 32Mb FRAM exhibits excellent ferroelectric properties such as remnent polarization of 15 w C/cm 2 at 3V. As a result, novel hydrogen-damage free 0.25 w m 15F 2 32Mb FRAM was successfully developed.