醇溶剂对炭气凝胶结构和电化学性能的影响

以间苯二酚和甲醛为原料、六次甲基四胺(HMTA)为催化交联剂,在不同种类醇溶剂中通过溶液 - 溶胶 - 凝胶、常温常压干燥和炭化处理制备炭气凝胶.N2吸附测试表明,醇溶剂体系制备炭气凝胶的比表面积在650～740 m2/g之间.乙醇为溶剂制备的炭气凝胶在20～40 nm有集中孔径分布,异丙醇为溶剂时孔径集中在3～4 nm之间,而以甲醇为溶剂时中孔含量相对较少.采用直流充放电法、交流阻抗法和循环伏安法测定以上述炭气凝胶为电极的超级电容器的电化学性能,结果表明,以乙醇为溶剂制备的炭气凝胶电极电容性能最佳,在0.5 A/g充放电时电极的比电容为180 F/g ,电流密度增大10倍容量保持率仍达到86%.合理的孔径分布和较大中孔有利于提高炭气凝胶电极的充放电特性.     

新型碳微球制备和电化学性质研究

以氨水作为催化剂,间苯二酚和甲醛为前驱体制备单分散酚醛(resorcinolformaldehyde,RF)树脂微球和碳微球.采用循环伏安法、电化学交流阻抗和恒电流充放电等方法对由RF树脂得到的碳微球的电化学性能的测试表明,其可以作为超级电容器电极材料.在扫描速率为1mV·s-1时,比电容为175.9F·g-1,电阻为0.5Ω,循环500圈后仍保持94.4%的电容量,具有优异循环寿命.结果表明,由酚醛树脂制备的单分散碳微球作为超级电容器的电极材料具有降低离子运输阻力和提高超级电容器稳定性的功能.     

国内期刊亮点

<正>石墨烯/炭气凝胶的制备及其结构与性能研究炭气凝胶是具有独特三维网络结构的轻质纳米中孔炭材料,适用于制备超级电容器的电极,但通常采用苯二酚(R)-甲醛(F)为原料制备的炭气凝胶,其微孔含量低,比表面积和电容量不高,限制了它在超级电容器中的应用。若采用石墨烯(GO)与炭气凝胶复合,可在一定程度上有效调控气凝胶的比表面积,但要进一步提高炭气凝胶的比电容,仍存在较大难度。湖南大学材料科学与     

炭气凝胶的常压制备及其超级电容器行为

采用溶胶一凝胶法,以间苯二酚（R）和糠醛（F）为原料,环六次甲基四胺（HMTA）作催化交联剂,通过常压干燥和高温碳化、活化等工艺制备分散性良好的炭气凝胶．研究溶剂的pH值和活化温度等工艺参数对炭气凝胶的比表面积和用作超级电容器电极的比电容的影响．确立具有最大比电容时炭气凝胶的最佳制备工艺条件．结果表明,当pH-9．0,活化温度为950℃时获得的炭气凝胶具有最大的比表面和．比电容．     

炭气凝胶微球的制备及在锂离子电池负极材料中的应用

以间苯二酚和甲醛为原料,在催化剂和表面活性剂的作用下经溶胶-凝胶、超临界干燥、炭化等过程合成一种新型的炭气凝胶微球。采 用扫描电镜(SEM)、X-射线衍射(XRD)、低温氮吸附（BET）和充放电测试等表征了炭气凝胶微球微观形貌、结构和电化学性能。结果表明:炭气 凝胶微球具有纳米网络结构（孔径集中分布在3.5nm左右）,微球直径≤40μm,比表面积为555m²/g。电化学性能表现出很大的首次不可逆容量 损失,这主要与材料大的比表面积有关。但在首次循环后,具有良好的循环性能,循环20次后可逆充电容量为281mAh/g,循环效率达到100％ 。     

聚乙烯醇-氢氧化钾-硫氰酸钾凝胶电解质在超级电容器中的应用研究

制备了一种具有氧化还原活性的聚乙烯醇-氢氧化钾-硫氰酸钾(PVA-KOH-KSCN)凝胶电解质,用于活性炭超级电容器的研究.利用循环伏安法、恒电流充放电、交流阻抗谱等电化学测试方法进行表征.结果表明,KSCN的引入提高了电解质的电导率和电极的电容.在相同电流密度时,以PVA-KOH-KSCN为凝胶电解质的超级电容器电极比电容比以PVA-KOH为凝胶电解质的提高了约73%,达到209.48F/g,此外,超级电容器还表现出良好的循环稳定性.     

用于超级电容器电极材料的球形炭气凝胶

以2,4-二羟基苯甲酸(D)和甲醛(F)为原料,碳酸钾(C)为催化剂,采用溶胶-凝胶和乳液聚合的方法合成出球形炭气凝胶。利用SEM、粒径分布和BET测试法对样品的形貌和孔结构进行了分析。以制备的球形炭气凝胶作为超级电容器电极材料,利用恒流充放电研究其电容特性,考察了干燥方式和n_D/n_C对比电容的影响。结果表明,超临界干燥下,n_D/n_C为100的样品具有467m²/g的比表面积,孔径主要分布在2.5nm左右,在充放电电流密度为50mA/g时的比电容可达142F/g,该电极具有较好的循环性能和功率特性.     

酚醛树脂基活性炭微球的制备及其电化学性能

以苯酚和甲醛为原料,盐酸为催化剂,制备醇溶性酚醛树脂前驱体,探讨炭化温度对炭微球性能的影响,并将炭微球在3 mol/L HNO3溶液中活化后得到活性炭微球。利用红外光谱、X线衍射(XRD)、扫描电镜(SEM)、循环伏安、恒流充放电、循环寿命等对该材料进行表征及电化学性能测试。研究结果表明:炭微球的最佳炭化温度为750℃,在该温度下制备的炭微球具有良好的球形形貌,其结构为部分石墨化的无定形炭;活性炭微球作为电容器电极材料具有良好的电化学性能,在1 mV/s扫描速度下比电容达到247.8 F/g;在0.5 A/g电流密度充放电下扣式超级电容器比电容高达60 F/g,且充放电循环5 000次后比电容几乎没有衰减。     

冷压压力对镍基超级电容器电极材料电化学性能的调控

采用粉末压片法,以泡沫镍为集流体,制备镍基超级电容器电极材料.在冷压压力为2～10 MPa时,采用扫描电镜观测样品的微观结构,以KOH溶液作为电解液,测试样品的循环伏安、恒流充放电、交流阻抗等电化学性能.研究结果表明:冷压压力对镍基超级电容器电极材料循环伏安特性、恒定电流充放电和交流阻抗的调控有积极的意义.     

弱结晶二氧化锰超级电容器充放电分析

以等物质的量的高锰酸钾和乙酸锰为原料,采用机械化学法制备出弱结晶型α-MnO2超级电容器电极材料.在1.2V电压内,200mA·g-1电流密度下对对称型超级电容器进行恒流充放电测试.采用XRD法、循环伏安及交流阻抗法对充放电前后电极材料的结构以及电化学性能进行表征,首次采用求斜率法对充放电曲线分析.结果表明:超级电容器表现出法拉第电容与双电层电容的双重特征;在循环过程中,电化学惰性物质Mn3O4生成,循环伏安图中氧化还原峰逐渐消失;充放电曲线的法拉第电容特征逐渐消失而接近双电层电容理想曲线;超级电容器的比容量、等效串联电阻发生了对应的变化,其最大电极比容量达到416F·g-1,经过近500次循环后,比容量为220F·g-1.     

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.