含菱形相的天然石墨用做锂离子电池负极材料

利用天然石墨的XRD结晶参数计算了5种天然石、圣样品的菱形石墨含量，采用恒电流充放电和循环伏安方法研究了天然石墨HT10在1mol／L LiPF6／EC EMC(1：1，体积比)和1mol／L LiPF6／EC EMC PC(3：3：4，体积比)电解液中的电化学性能．结果表明，HT10在2种电解液中均保持了较高的放电容量和较好的循环性能，且放电容量均在330mAh／g以上，首次库仑效率均大于87％．采用循环伏安和SEM分析了充放电过程中形成SEI膜的情况，良好的SEI膜保证了锂离子的通过而阻止溶剂的共嵌入；同时在1mol／L LiPF6／EC EMC PC(3：3：4，体积比)中石墨片层经多次充放电后剥离形成了疏松的多孔性物质．     

锂离子电池和双电层电容器用LiODFB-TEABF4复合盐电解液的研究

探讨在EC+PC+DMC复合溶剂体系中LiODFB-TEABF4复合盐电解液与LiFePO4锂离子电池及AC双电层电容器的相容性规律.研究结果表明:在LiODFB基电解液中加入TEABF4能显著提高电解液的电导率;对于LiFePO4电池体系,电解液中的TEABF4参与了SEI膜的成膜过程,但TEABF4浓度过高不利于电极材料的容量的提高;对于AC电容器体系,加入TEABF4可以有效改善电容器的双电层储能行为,同时显著提高电容,当TEABF4浓度为0.3 mol/L时,电容达到最大,比不添加TEABF4的纯LiODFB盐电解液的电容大.     

四氟硼酸四乙基铵对超级电容电池性能的影响

研究了四氟硼酸四乙基铵(Et4,NBF4)添加到LiPF6基电解液(碳酸乙烯酯(EC)+碳酸二甲酯(DMC)+碳酸甲乙酯(EMC)(质量比为1∶1∶1)对(LiMn2O4+活性炭(AC))/Li4Ti5O12超级电容电池电化学性能的影响.线性扫描(LSV)、循环伏安(CV)及电池充放电等测试结果表明:Et4NBF4盐改变了复合电解液中离子对的结构,提高了复合电解液的高电压稳定性和电导率.在实验条件下,随着复合盐电解液中Et4NBF4含量的增加,电池放电容量也增加,含有Et4NBF4与LiPF6物质的量的比为4∶1的电解液的电池电化学性能最好,在4C倍率下循环5,000周后,容量还有86.8,mA·h,保持率为95.8%.     

一种新型锂离子二次电池用有机电解液的性能研究

为了提高锂离子二次电池的笔容量和循环寿命,研究者们越来越重视有机电解液的使用及选择.实验选择了EC和DMC二元体系,将其以不同体积配比用于锂离子二次扣式电池中(正极材料为LiCoO2,负极材料为CMS,电解质盐为LiPF6)以研究电解液的电化学性能.通过实验,发现此种电解液的最佳配比为EC∶DMC=3∶7(1 mol/L LiPF6),此种电解液大大提高了电池的循环性能.     

一种新型锂离子二次电池用有机电解液的性能研究

为了提高锂离子二次电池的笔容量和循环寿命，研究者们越来越重视有机电解液的使用及选择。实验选择了EC和DMC二元体系．将其以不同体积配比用于锂离子二次扣式电池中（正极材料为LiCoO2．负极材料为CMS，电解质盐为LiPF6）以研究电解液的电化学性能。通过实验．发现此种电解液的最佳配比为EC：DMC=3：7（1mol／L LiPF6）．此种电解液大大提高了电池的循环性能。     

锂电池电解质草酸二氟硼酸锂水解过程及其对理化性能的影响

通过元素分析、红外(FTIR)对自制的高纯草酸二氟硼酸锂(LiODFB)的化学结构和成分进行分析和表征,通过水分暴露实验和电池性能测试综合对比分析LiODFB与LiPF6的水分敏感性和理化性能.研究结果表明:自制LiODFB的元素含量和理论值基本吻合,纯度达到99.93％;各化学键的红外吸收峰都存在,并且未见其他杂质峰;LiODFB在25℃和50％湿度下暴露2h后,吸潮形成LiODFB·H2O,随暴露时间延长,发生水解反应,生成复杂化合物;LiPF6在25℃和50％湿度下暴露,迅速反应生成LiF和Li3PO4等,同时放出HF气体;电池的放电容量和容量保持率均随着LiODFB和LiPF6的暴露时间延长而变差,在暴露时间相同时,与采用LiPF6的基电解液相比,采用LiODFB基电解液的电池的容量和容量保持率均明显较高.     

七甲基二硅氮烷对锰酸锂电池储存性能的影响

为改善锰酸锂的储存性能,以七甲基二硅氮烷为电解液添加剂、自制的LiPF6/EC+DMC+EMC为电解液,研究不同温度下七甲基二硅氮烷对不同荷电态的锰酸锂电池储存性能的影响,并采用扫描电镜、EIS及充放电方法对电极表面形貌及电池电化学性能进行表征和测试.实验结果表明:锰酸锂电池在常温和高温储存1周后,处于放电态电池的循环性能均比处于半电态和满电态的电池的循环性能更优异.放电态的锰酸锂电池常温储存1月后,首次充放电效率为95.22％,2C倍率下循环200次后,容量保持率为96.74％,与电解液中未加七甲基二硅氮烷的锰酸锂电池相比,表现出较好的储存性能.     

LiODFB-LiPF6基电解液与活性炭电极的相容性研究

在活性炭超级电容器体系中,研究LiODFB与LiPF6组成的复合盐电解液与活性炭电极的相容性规律.研究结果表明:在LiODFB基电解液中加入LiPF6电解质盐能显著提高电解液的电导率;LiODFB-LiPF6复合盐电解液与活性炭电极材料有较好的相容性,但LiPF6浓度过大不利于双电层电容特性的发挥;在电解液中加入少量的LiPF6可有效增加双电层电容量;当LiPF6浓度为0.2 mol/L时,电容器容量达到最大;不添加LiPF6的纯LiODFB盐电解液的容最大,且l 500次循环的容量保持率超过96%.     

2-噻吩甲腈在高电压锂离子电池中的应用

为了改善锂离子电池在高电压下的电化学性能,以2-噻吩甲腈作为一种新型的电解液添加剂,采用线性扫描伏安法(LSV)研究其对1 mol/L Li PF6/EC+EMC(EC与EMC质量分数之比为1:2)电解液电化学窗口的影响。通过扫描电镜(SEM)、X线光电子能谱(XPS)、傅里叶红外光谱(IR)、充放电测试、循环伏安(CV)和交流阻抗(EIS)对含不同电解液的锂离子电池循环前后的正极材料表面及其电化学性能进行表征。研究结果表明:2-噻吩甲腈能优先于电解液溶剂发生氧化分解反应并在正极表面形成致密的导电聚合物膜;添加质量分数为0.1%2-噻吩甲腈的钴酸锂电池在3.0~4.5 V以0.5 C倍率循环100次后容量保持率高达91.99%,在5C倍率下放电比容量为152.8m A·h·g-1;与电解液中未添加2-噻吩甲腈的电池相比,其循环后电荷转移阻抗的增加被抑制,在高电压下表现出较好的循环和倍率性能。     

锂离子电池负极材料纳米Ni3Sn2的溶剂热合成与电化学性能

采用溶剂热法合成锂离子电池负极材料纳米Ni3Sn2合金粉末并研究了该合金粉末作为新型锂离子二次电池负极材料的电化学性能。合成的合金粉末经过了XRD和FESEM的表征,采用Li/LiPF6(EC DMC)/Ni3Sn2模拟电池测定合成的合金粉末的电化学性能。研究表明,该合金粉末的首次可逆容量为136mAh.g-1,退火后的合金粉末表现出更好的循环稳定性。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.