新能源汽车电池负极材料的制备与性能研究

采用原位合成法制备了镍-氧化镍/多孔碳纳米片（Ni-NiO/PCNs）负极材料,对比分析了氯化钠模板、退火温度和退火时间对负极材料物相组成、显微形貌和电化学性能的影响。结果表明,Ni/PCNs、Ni-NiO/C和Ni-NiO/PCNs负极材料都主要含有镍和无定型C相,且后2种负极材料还含有氧化镍相;300 ℃/4 h为Ni-NiO/PCNs负极材料适宜的退火工艺,此时Ni-NiO/PCNs负极材料中Ni-NiO粒子分散性较好且保持着三维片层结构,平均尺寸约为27 nm,Ni-NiO实现了对无定型C的包裹;退火时间过长（6 h）会使得镍粒子过氧化且发生团聚,而温度过高（400 ℃）会使得粒子以团聚为主,三维片层状结构消失。电流密度为1 A/g、循环5 000圈后Ni-NiO/PCNs负极材料的放电比容量为235 mA·h/g,此时的放电比容量约为首圈放电比容量的83.93%;Ni-NiO/C和Ni/PCNs负极材料在充放电循环过程中以及循环5 000圈后的放电比容量和容量保持率都明显低于Ni-NiO/PCNs负极材料,Ni-NiO/PCNs负极材料具有更好的循环稳定性,这主要与其具有独特的多孔三维片层结构有关。     

Electrochemical characteristic of chemical-mechanical polishing of copper with oxide passive film

1　INTRODUCTIONThankstoitslowresistivityandhighelectromi grationresistance ,copperappearstobeaverypromisingsubstituteforaluminumininterconnec tions[1] .However ,copperisverydifficulttopattern ,andonlychemical mechanicalpolishing (CMP)tech nologycanresolvethisproblem[2 ] .CMPwasinitiallyinvestigatedandopenedoutfrom 1980soverseas[3] ,anditisthebestandonlyglobalplanarizationtech nologyatpresent ,butkeepsholdofbusinesssecretsallthetime .Fayolleetal[2 ] researchedCMPprocessofcopperwhereFe(…     

Zr替代Ti对Ti19．5V40Mn16．2Cr9．8Ni14．5合金的影响Ⅱ：电化学性能

在对合金微观结构和储氢性能研究的基础上，详细考察了少量Zr取代Ti对Ti19．5V40Mn16．2Cr9．8Ni14．5合金电化学性能的影响。通过观察电极的充放电行为，并结合EIS及多种极化曲线的分析结果，发现少量Zr对Ti的取代能够显著提高合金电极的实际电化学容量和循环稳定性，而且还能在一定程度上改善合金的电极动力学性能。对于这些性能的改善，从合金微观结构方面进行了解释。     

移动式阴极的扫描参数对脉冲电化学光整加工的影响分析

移动式阴极在脉冲电化学光整加工中的应用，有效地改善了流场、电场及温度场的分布，在简化阴极设计的同时，提高了光整效果。通过理论并结合实验分析表明：扫描参数的合理匹配是提高脉冲电化学光整加工效果的关键工艺因素之一。实验中，在参数适当匹配并结合其他参数的条件下，对试件表面经少许几次扫描后，将试件的原始表面粗糙度Ra由1．7μm降至0．2μm以下。     

绝缘栅双极晶体管脉冲斩波器的设计与应用

高频脉冲电流加工及光整加工技术能提高零件的加工精度和表面质量。脉冲斩波器的设计是应用该技术的关键所在。介绍了脉冲电源的构成原理及设计思路，并采用绝缘栅双极晶体管(1GBT)设计制造出高频、大电流脉冲斩波器。用所设计的脉冲电源进行了脉冲电化学光整加工实验，得到了满意的结果。     

TiO_2直接电解还原过程的研究

采用SEM、EDS、XRD等方法对TiO2直接电化学还原产物进行分析,指出TiO2电极的还原是从外向内由高价到低价再到金属逐步进行的。对还原过程中电流、还原气相产物的分析结果表明:还原过程电流效率低,并且电流效率随电解时间延续而降低,阳极产物CO、CO2与阴极中间产物Ca发生副反应以及副反应产物炭黑造成电流短路是电流效率低的主要原因。提高电流效率的途径有两条:一是增大阴、阳极间距,减小副反应的发生;二是使电解池表面熔盐不断导出,或采取某一隔离措施,使副反应产生的炭黑在阴、阳极之间不造成电流短路。     

La替代Mm对低钴AB5型贮氢合金电化学性能的影响

用XRD和SEM测试了稀土基低钻AB5型LaxMm1-x（NiMnSiAlFe）4．7Co0.2（x=0,1）贮氢合金的微观结构，并全面测试了合金在铸态及快淬态下的电化学性能。研究了La替代Mm对铸态及快淬态低钻贮氢合金微观结构及电化学性能的影响。对合金的电化学性能研究结果表明：La替代Mm使合金的放电容量提高，并使铸态合金的循环寿命由341次提高到370次；La替代Mm使得快淬态合金的循环寿命的增加幅度较小，主要原因是La替代Mm使快淬态合金的晶粒粗化。微观结构测试结果表明：La替代Mm使合金中的第二相消失，并使合金的晶格常数在a轴方向增加，在c轴方向略有减小，晶胞体积增大，这是La替代Mm使合金放电容量提高的主要原因。     

Effect of annealing treatment on electrochemical property of LiNi0.5Mn1.5O4 spinel

LiNi0.5Mn1.5O4 was prepared under different cooling conditions. The electrochemical properties of LiNi0.5Mn1.5O4 prepared under different cooling conditions were investigated. The results show that LiNi0.5Mn1.5O4 synthesized with or without annealing treatment has similar X-ray diffraction patterns that can be indexed to cubic spinel structure. The mass loss occurring above 650℃ during the heating process can be mostly gained during the cooling process. LiNi0.5Mn1.5O4 synthesized with an annealing treatment exhibits almost one voltage plateau at around 4.7 V and higher capacity with a quick fading upon cycling, whereas LiNi0.5Mn1.5O4 synthesized without annealing treatment shows two voltage plateaus at around 4.1 and 4.7 V and superior capacity retention upon cycling both at rates of 1/7C and 1 C, though the capacity is not high.     

Low-melting-point titanium-base brazing alloys—part 2: Characteristics of brazing Ti-21Ni-14Cu on Ti-6Al-4v substrate

Filler metal of a low-melting-point (917 °C) Ti-21Ni-14Cu was brazed onto the substrate of Ti-6Al-4V alloy at 960 °C for 2,4, and 8 h to investigate the microstructural evolution and electrochemical characteristics of the brazed metal as a function of the period of brazing time. Optical microscopy, scanning and transmission electron microscopy, and x-ray diffractometry were used to characterize the microstructure and phase of the brazed metal; also, the potentiostat was used for corrosion study. Experimental results indicate that diffusion of copper and nickel from the filler metal into the equiaxed a plus intergranular β structure of Ti-6Al-4V substrate causes the lamellar Widmanstätten structure to form. The intermetallic Ti₂Ni phase existing in the prior filler metal diminishes, while the Ti₂Cu phase can be identified for the metal brazed at 960 °C for 2 h, but the latter phase decreases with time. Advantage might be taken from the evidence of faster diffusion of nickel than copper along the β phase to the substrate. In deaerated Hank’s solution, corrosion potential, corrosion current density, and critical potential for active-to-passive transition decrease while the passivation range broadens with the period of brazing time. However, all the brazed metals, immersed for different periods in oxygen-saturated Hank’s solution, show similar corrosion behavior, irrespective of the brazing time.