石墨化中间相炭微球表面镀银的电化学性能

采用化学镀的方法在中间相炭微球的表面镀覆金属银,通过扫描电镜分析镀银后炭微球的表面形貌,利用X射线衍射对试样进行物相分析.将镀银的中间相炭微球用作锂离子电池负极材料,测试其电化学性能.研究结果表明:金属银镀覆在中间相炭微球的表面,随着镀银含量的增加,镀银中间相炭微球的首次放电容量升高,银含量16.5%的中间相炭微球的首次放电容量升高12.6mA·h/g;在湿度为25%的气氛中搁置12h后,未镀银的炭微球的放电容量降低16.3mA·h/g,循环稳定性变弱,20次循环后容量保持率为74.6%,而镀银量为16.5%炭微球的首次放电容量只降低6.1mA·h/g,并且循环稳定性强,20次循环后容量保持率为95.8%,说明镀银后中间相炭微球在潮湿条件下的电化学性能得到改善.     

中间相炭微球的粒径对其结构和性能的影响

采用X射线衍射、粒径分析、扫描电子显微镜、BET比表面积分析及电化学方法研究了粒径对中间相炭微球结构和性能的影响.研究结果表明:随着粒径的增加,中间相炭微球的堆积密度增大,比表面积减小;中间相炭微球电极的充电容量和不可逆容量减小,可逆容量与首次充放电效率增加;以中间相炭微球为负极制成063448型锂离子电池的放电容量随着中间相炭微球平均粒径的增大而增加,不可逆容量减少;以平均粒径为19.09μm的中间相炭微球为负极制成的电池放电容量为838 mA·h,首次充放电效率为87.29%,循环100次后的容量保持率为92.4%.     

具有电容和脱嵌锂特性的锂离子电池复合负极材料性能

以中间相炭微球和活性炭为原料,采用物理混合的方法制备锂离子电池复合负极材料.用扫描电镜、X线衍射仪、恒电流充放电和循环伏安(CV)测试来表征材料的表面形貌、结构和电化学性能.研究结果表明:制备复合材料的中间相炭微球和活性炭混合均匀;复合材料首次放电和充电比容量分别为549和290 mA-h/g,当电压为0.25～3.00 V时,复合材料充电曲线斜率介于中间相炭微球和活性炭的充电曲线斜率之间,比容量为93 mA-h/g,显示复合负极材料同时具有脱嵌锂特性和双电层特性;循环30次后,复合材料的放电容量为240 mA-h/g;在充放电电流密度为4 A/g时,复合材料的电化学极化较中间相炭微球的极化显著降低,是一种具有发展前途的锂离子电池负极材料.     

中间相炭-天然石墨球复合材料的制备及电化学性能

以煤焦油为原料在天然石墨球表面包覆一层中间相炭制备复合炭材料,研究中间相炭、天然石墨球和复合炭材料作为锂离子二次电池炭负极材料的电化学性能,并考察不同温度热处理得到的复合炭材料的电化学性能。研究结果表明：复合炭材料同时具有中间相炭及天然石墨球的优点;随着热处理温度的升高,复合炭材料的充放电容量有所降低,于700℃处理2 h的性能最佳,首次充电容量达378 mA.h/g,首次充放电效率为91.3%。复合炭材料在Li/C扣式电池中的循环性能得到提高,50个循环后容量保持率为96%。     

聚合物锂离子电池负极电化学性能研究

制备了聚合物锂离子电池用负极 ,对其首次充放电效率、比容量、不同放电倍率下放电性能进行了测试 .首次充放电容量分别为 340 m A· h·g- 1和 310 m A·h· g- l,库仑效率可达 91% .以锂锰氧为正极组装了聚合物锂离子电池 ,通过测试表明制备的聚合物锂离子电池具有较好的循环性和大电流放电能力 .所制负极可应用于聚合物锂离子电池中 .     

硬炭微球的制备及其储锂性能研究

以二乙烯基苯(DVB)为交联剂、偶氮二异丁腈(AIBN)为引发剂、聚乙烯吡咯烷酮(PVP)为模版剂,通过自组装,制备聚苯乙烯微球。经过氧化和高温炭化转换成硬炭微球。考察了硬炭微球作为锂离子负极材料的电化学性能。结果表明硬炭微球的首次放电比容量为505 mA·h/g,40次循环后保持在304 mA·h/g。     

锂离子电池炭负极的结构与特性及其电化学性能

通过计算边缘碳原子及表面碳原子含量计算,研究边缘碳及表面碳原子含量对炭材料的电化学性能的作用机理。导出炭材料的结构与物理特性对炭材料的嵌锂性能的影响。通过对不同形貌、粒径、比表面积及有序程度的人造石墨、中间相炭微球及热解炭的电化学性能的研究,验证该机理的正确性。应用这一机理分析对人造石墨进行热处理改性,以及在人造石墨表面包覆无定形炭的改性作用。研究结果表明:边缘碳及表面碳原子的含量对固体-电解质中间相(SEI)膜的形成以及SEI膜的均匀、稳定性具有重要的作用,从而影响炭材料的首次不可逆容量及循环性能。     

热处理时间对锂离子电池阳极用中间相炭微球充放电性能的影响

利用小角X射线散射（SAXS）及恒电流方法对不同时间热处理的中间相炭微球（MCMBs)的微观物理结构及充放电性能进行了研究。结果表明，随着热处理时间的延长，MCMBs内部的微孔孔径分布先变宽而后变窄，最可几孔径先增加尔后逐渐减小。随着热处理时间的延长MCMBs的首次充电可逆容量和库伦效率逐渐减小，而首次不可逆容量逐渐增加，MCMBs内部的微孔起到了储存锂离子的作用。     

锂离子电池正极材料尖晶石型LiMn2O4的制备及其掺杂改性

采用固相合成法制备了锂离子电池用尖晶石型LiMn2O4正极材料,并通过同时加入Cr3 和F对材料进行了体相掺杂改性.用扫描电子显微镜和X射线衍射研究了材料的表面形貌和晶体结构,用充放电循环实验对制备的锂离子电池性能进行了测试.结果表明:未掺杂的LiMn2O4正极材料首次放电容量为115.3mAh·g-1,循环25次后容量降为96mAh·g-1;掺杂Cr3 和F的材料同样具有尖晶石型结构,随掺杂量增加,首次放电容量略有降低,但循环性能有较明显改善,充放电效率提高,其中掺杂量为0.10的样品首次放电容量为111.5 mAh·g-1,循环25次后容量保持率达91.8%.     

LiFe1-xMgxPO4锂离子电池正极材料的电化学性能

采用体相掺杂法对LiFePO4进行改性,采用Mg对LiFePO4进行掺杂,研究Mg的掺杂量对LiFePO4材料电化学性能的影响.研究结果表明,经掺杂改性后的LiFe1-xMgxPO4(x=0.01,0.05,0.10,0.15)材料的充放电容量和循环性能均有所提高,其中,样品LiFe0.85Mg0.15PO4的性能最佳,其首次放电容量为125.6 mA·h/g,循环6次后容量仍达123.0 mA·h/g;Mg部分取代LiFePO4材料中的Fe后所得材料的电子电导率提高了1×106倍,从而提高了材料的电化学性能.     

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.