锂离子电池硅碳复合负极材料的研究进展

锂离子电池发展至今,因其优异的性能,已成为新能源领域发展中的宠儿,大容量高倍率特性是目前该电池最重要的研究方向。具有高比容量和较低电压平台的硅成功的吸引了人们的眼球,有望成为下一代锂离子电池的主要负极材料。根据近十多年来锂离子电池硅碳复合负极材料的研究成果,本文讨论了硅碳复合材料的制备方法,综述了国内外该材料的研究进展,系统地总结了目前硅碳材料改性的优势和不足,建议了今后应努力的方向和硅碳负极材料发展趋势。     

锂离子电池硅碳负极材料研究进展

硅基材料作为锂离子电池负极具有容量高、来源广泛以及环境友好等优势,有望替代目前应用广泛的石墨负极成为下一代锂离子电池的主要负极材料。硅和碳复合构成的锂离子电池复合负极,不但解决了充放电过程中硅体积效应大和碳容量低的问题,而且综合了碳循环性好和硅容量高的特点。从材料选择、结构设计以及电极优化方面简要介绍了硅/碳复合材料的最新研究进展,并对硅碳复合负极未来发展方向进行了展望。     

锂离子电池多孔硅基复合负极材料的研究进展

概述了多孔硅基负极材料在锂离子电池中的应用,重点介绍了材料结构和复合方式对其电化学性能的影响;分析了导致其循环性能降低的主要原因,指出控制电池循环过程中硅基材料体积变化、抑制SEI膜的增加是改善硅基负极材料循环性能的重要途径. 对多孔硅基复合负极材料的研究进行了展望,提出在纳米化和复合化的基础上,设计特殊孔道结构、制备多孔的硅/碳复合材料是推进硅基负极材料应用的重要研究方向.     

TiO_2基锂离子电池复合负极材料的研究进展

TiO_2锂离子电池负极材料以其安全性高而著称,其被设计为各种纳米结构并与其他导电性好的材料制备成复合材料,以弥补其导电、导锂能力的不足。本文针对近年来TiO_2基复合材料作为锂离子电池负极材料的研究现状,介绍了碳类、硅类和金属类材料与TiO_2进行复合制备负极材料的可行方法,并分别分析了这3类材料的优缺点:碳类负极材料技术成熟,但有易燃的缺点;硅类负极材料理论容量高,但循环性能差且安全性不好;金属类负极材料普遍导电性好,且易与其他材料合金化,但循环性能差。最终提出,由于碳类负极材料技术成熟,且TiO_2可弥补其易燃的缺点;结合碳基材料优良导电性能与TiO_2优异安全性能的复合材料最有望实现工业化,将是锂离子电池领域重要的研究方向之一。     

锂离子电池负极用碳/硅复合材料的研究进展

硅(Si)因具有资源丰富、理论容量高、绿色环保等优点成为世界上最具有前景的锂离子电池负极材料之一。但硅的导电性能差,且在合金化/去合金化过程中会发生剧烈的体积膨胀导致电池循环稳定性严重下降。碳材料(C)导电性能优异且结构稳定。将C和Si进行复合,可得到容量高且循环性能好的锂离子电池负极材料。本综述从材料的制备方法着手,总结了锂离子电池C/Si复合负极材料的最新研究进展,探讨了制备方法、材料结构对C/Si复合负极材料储锂性能的影响。     

简讯

日本一家公司最近开发出锂离子电池制造新技术,利用硅氧化物、纳米硅、碳等生成的新型材料制作电池负极,使电池容量比目前使用石墨作负极的锂离子电池增加2至5成。硅具有价格低廉且对锂离子的吸收率高等特点,适合制造大容量电池。但是,硅吸收锂离子时的膨胀率也很高,用作电池负极易产生裂缝,进而缩短电池寿命。因此,硅材料制成的锂离子电池负极一直没能实用化。据《日经产业新闻》日前报道,日立万胜公司采用新技术,让纳米硅散布于硅氧化物材料内部形成“含纳米硅化合物,再混合这种“含纳米硅化合物和碳材料,形成“纳米硅多孔质复合材料。这…     

SnO_2复合材料作为锂离子电池负极的研究进展

综述了SnO_2复合材料作为锂离子电池负极材料方面的研究,从碳复合材料、石墨烯复合材料、金属复合材料以及其他种类的复合材料4个方面介绍了SnO_2复合材料作为锂离子电池负极材料的研究进展,并对SnO_2复合材料作为锂离子电池负极材料的发展前景进行了展望。     

锂离子电池用硅基复合材料的研究进展

锂离子电池硅负极材料具有很高的理论比容量(4200 m Ah/g),但其在充放电过程中巨大的体积变化导致循环性能很差,同时较低的电导率也限制了硅在锂离子电池中的应用前景。将硅与其它材料进行复合是改善硅基负极材料循环稳定性、提高其倍率性能的主要途径。文章综述了近年来硅基复合材料的研究进展,以期为硅基复合材料的研究提供参考。     

锂电池负极材料的研究进展

随着科技的发展,锂离子电池应用的范围越来越广。负极材料作为锂离子电池重要部分,越来越多的被人们研究开发。本文从碳负极材料和非碳负极材料两个方面对锂离子负极材料的研究发展进行了汇总,同时对其制备也进行了简单综述。     

锂离子电池二硫化钼基负极材料研究进展

锂离子电池以其便携、无记忆效应、循环寿命长等特点广泛应用于移动电子设备、电动汽车等领域。负极材料的改进是制备新型高性能锂离子电池的重要环节。具有类石墨烯结构的二硫化钼是极具发展潜力的锂离子电池用负极材料。但纯二硫化钼导电性差、充放电过程中体积膨胀率高,导致其可逆容量低、容量保持率差。复合化与纳米化是解决上述问题的有效途径。综述了近年来用于锂离子电池负极材料的二硫化钼基复合材料研究进展,重点介绍了二硫化钼/碳和二硫化钼/过渡金属化合物体系的形貌特征、比容量、循环稳定性等,并对二硫化钼基负极材料的发展趋势进行了展望。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。