磷酸铁锂掺杂改性中Li位和Fe位掺杂效果分析

对LiFePO4的不同位金属离子掺杂改性进行了研究,采用共沉淀法合成Li位和Fe位Mg2+、Mo6+掺杂的LiFePO4正极材料,通过XRD、XPS、充放电曲线以及CV、Mott-Schottky对材料进行表征和测试,主要分析了金属离子在Li位和Fe位掺杂对材料性能的影响。结果表明Mg2+和Mo6+可以分别在Fe位和Li位掺杂,且不会影响磷酸铁锂的橄榄石结构,掺杂可以改善材料的电化学性能。从掺杂效果来看,Fe位掺杂比Li位掺杂更优越,从材料的晶体结构和半导体性质着手对掺杂机理作了分析讨论。

InSb的Li替位形成能的从头计算

采用基于平面波展开的第一原理赝势法计算了锑化铟在锂替位到铟位置时的各种情况下的形成能与电子结构 ,讨论了锂替位的体积变化 ,电荷分布、能带结构及电子态密度等性质 .结果表明 ,对于闪锌矿结构的 In Sb,锂的各种替位形成能大致在每个锂原子 -2 .2 e V左右 .该结果表明 ,不可能在嵌入初期 Li插入到间隙位置之前发生替位反应 。

Corrosion behavior of 2A97 Al-Cu-Li alloys in different thermomechanical conditions by quasi-in-situ analysis

As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al-Cu-Li alloy,cold working and artificial aging were carried out to produce 2A97 Al-Cu-Li alloys under different thermomechanical conditions.Quasi-in-situ analysis,traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys.It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts,which determines corrosion susceptibility of alloys,whereas grain-stored energy distribution is closely associated with localized corrosion propagation.It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests,which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.

High density dislocations enhance creep ageing response and mechanical properties in 2195 alloy sheet

The creep strain of conventionally treated 2195 alloy is very low,increasing the difficulty of manufacturing Al-Cu-Li alloy sheet parts by creep age forming.Therefore,finding a solution to improve the creep formability of Al-Cu-Li alloy is vital.A thorough comparison of the effects of cryo-deformation and ambient temperature large pre-deformation(LPD)on the creep ageing response in the 2195 alloy sheet at 160℃with different stresses has been made.The evolution of dislocations and precipitates during creep ageing of LPD alloys are revealed by X-ray diffraction and transmission electron microscopy.High-quality 2195 alloy sheet largely pre-deformed by 80%without edge-cracking is obtained by cryo-rolling at liquid nitrogen temperature,while severe edge-cracking occurs during room temperature rolling.The creep formability and strength of the 2195 alloy are both enhanced by introducing pre-existing dislocations with a density over 1.4×10^(15)m^(−2).At 160℃and 150 MPa,creep strain and creep-aged strength generally increases by 4−6 times and 30−50 MPa in the LPD sample,respectively,compared to conventional T3 alloy counterpart.The elongation of creep-aged LPD sample is low but remains relevant for application.The high-density dislocations,though existing in the form of dislocation tangles,promote the formation of refined T1 precipitates with a uniform dispersion.

Improvement of strength and ductility of Al-Cu-Li alloy through cryogenic rolling followed by aging

To develop an improved approach in achieving an excellent combination of high strength and ductility,the solutionized Al?Cu?Li plates were subjected to rolling at cryogenic and room temperatures,respectively,to a reduction of83%,followed by aging treatment at160°C.The results indicate that Al?Cu?Li alloys through cryogenic rolling followed by aging treatment possess better mechanical properties.Rolling at cryogenic temperature produces a high density of dislocations because of the suppression of dynamic recovery,which in turn promotes the precipitation of T1(Al2CuLi)precipitates during aging.Such high density of T1precipitates enable effective dislocation pinning,leading to an increase in strength and ductility.In contrast,room temperature rolled alloys after aging treatment exhibit lower strength and ductility due to low density of T1precipitates in the grain interior and high density of T1precipitates around subgrain boundaries.

Multifunctional interfacial and structural anode for dendrite-free lithium metal-based batteries

Lithium(Li)metal is considered as the candidate for the next generation of Li metal battery(LMB)anodes due to its high capacity and the lowest potential,which is expected to meet the requirements of energy storage devices.Unfortunately,the uncontrollable growth of Li dendrites during the charge/discharge process,as well as the resulting problems of poor cycling stability,low coulomb efficiency and safety risk,has restricted the commercialization of Li anode.Herein,an in-situ interfacial film containing three-dimensional(3D)rod-like micron-structure silver(Ag)is constructed on the surface of the Li metal.Due to the 3D rod-like micron-structure used to homogenize the distribution of current density,achieving uniform nucleation and growth of electrodeposited Li,the produced Li-Ag alloy was employed to restrain the formation of“dead”Li and the in-situ formed LiNO_(3) was utilized to facilitate the stability of solid-electrolyte interface(SEI)film,so the growth of dendritic Li is suppressed via the synergistic effect of structure and surface chemistry regulation.The obtained Li anode can achieve cycling stability at a high current density of 10 mA/cm^(2).This work considers multiaspect factors inducing uniform Li electrodeposition,and provides new insights for the commercialization of LMB.

Geochronology, petrogenesis and tectonic significance of Dahongliutan pluton in Western Kunlun orogenic belt, NW China

The Dahongliutan granitic pluton,in the eastern part of the West Kunlun orogenic belt,provides significant insights for studying the tectonic evolution of West Kunlun.This paper presents a systematic study of LA-ICP-MS zircon U Pb age,major and trace elements,Sr-Nd-Hf isotopes,and the first detailed Li isotope analysis of the Dahongliutan pluton.LA-ICP-MS zircon U Pb dating shows that the Dahongliutan granites were emplaced in the Late Triassic((213±2.1)Ma).Geochemical data show relatively high SiO2 contents(68.45 wt%73.62 wt%)and aluminum saturation index(A/CNK=1.111.21)indicates peraluminous high-K calc-alkaline granite.The Dahongliutan granites are relatively high in light rare earth elements(LREE)and large ion lithophile elements(LILEs)(e.g.,Rb,K,Th),and relatively depleted in high field strength elements(HFSEs)(e.g.,Nb,Ta,P,Ti).TheεNd(t)values range from 8.71 to 4.73,and(87Sr/86Sr)i=0.70870.71574.Zircons from the pluton yield 176Hf/177Hf values of 0.2826181 to 0.2827683,andεHf(t)values are around 0;the two-stage Hf model ages range from 0.974 to 1.307 Ga.Theδ7Li values are 0.76‰3.25‰,with an average of 2.53‰.Isotopic compositions of the pluton suggest a mixed trend between the partial melting of the Middle Proterozoic ancient crustal material and a juvenile mantle-derived material.This study infers that the Dahongliutan rock mass is formed in the post-collisional extension environment,when the collision between South Kunlun and the Tianshuihai terranes results in the closure of the Palaeo-Tethys.The mantle-derived magma results in partial melting of the lower crust.