锂离子电池硅基负极黏结剂的研究新进展

硅具有较高的理论比容量,被认为是极具应用前景的锂离子电池负极材料。然而,硅在充放电过程中会产生巨大的体积变化,导致电极粉化脱落和容量的迅速下降,限制了硅基负极材料的应用。黏结剂是锂离子电池中一个不可或缺的组成部分,对体积变化较大的硅基负极而言,除了满足作为锂离子电池黏结剂的基本要求外,对黏结剂的结构和性能又提出了新的要求,黏结剂的选择对于增强硅基电极结构的稳定性并实现长期循环具有更加重要的意义。总结了近年来硅基负极材料黏结剂的研究进展,重点介绍了用于硅基负极材料的交联类黏结剂、导电类黏结剂和自修复类黏结剂等几种黏结剂的性能特点和应用,为选择和设计更加适合的硅基负极黏结剂提供研究建议。     

锂离子电池硅基负极黏结剂的研究新进展

硅具有较高的理论比容量,被认为是极具应用前景的锂离子电池负极材料。然而,硅在充放电过程中会产生巨大的体积变化,导致电极粉化脱落和容量的迅速下降,限制了硅基负极材料的应用。黏结剂是锂离子电池中一个不可或缺的组成部分,对体积变化较大的硅基负极而言,除了满足作为锂离子电池黏结剂的基本要求外,对黏结剂的结构和性能又提出了新的要求,黏结剂的选择对于增强硅基电极结构的稳定性并实现长期循环具有更加重要的意义。总结了近年来硅基负极材料黏结剂的研究进展,重点介绍了用于硅基负极材料的交联类黏结剂、导电类黏结剂和自修复类黏结剂等几种黏结剂的性能特点和应用,为选择和设计更加适合的硅基负极黏结剂提供研究建议。     

锂离子电池柔性碳布负极材料的储锂性能研究

将柔性碳布用于锂离子电池负极材料,用循环伏安法及交流阻抗研究了电池电极材料的电化学性能,用充放电实验研究了电池的循环性能和倍率性能。结果表明,锂离子电池负极采用柔性碳布,具有高的锂储存容量,第一次放电比容量为157.48mAh/g,并且在随后各次的容量损失很小,电池循环趋于稳定。     

锂离子电池大容量硅基负极材料的研究进展

高容量锂离子电池是目前新能源电池的研究重点之一。由于硅的理论容量(4 200mAh/g)是石墨电极材料容量(372mAh/g)的十倍以上,因而成为锂离子电池负极材料的研究热点。然而,在充放电过程中,由于硅电极体积变化较大,可造成活性物质的破坏和失效,导致其循环性能变差。此外,硅的电导率较低,并且与传统电解质的相容性较差。这些缺点严重影响了硅的电化学性能,限制了其在锂离子电池领域的广泛应用。综述了锂离子电池硅基负极材料的研究进展,探讨了高性能硅基复合电极材料的制备方法。     

锂离子电池负极材料研究进展

锂离子电池负极材料的电化学性能直接影响锂离子电池导电性、储锂容量、倍率特性和循环稳定性等,本文对近年锂离子电池负极材料研究方面的主要成果进行了综述,着重关注几种热点负极材料及其设计、实现与性能优化研究。比较了不同负极材料的特性,总结了相关的研究成果。     

锂离子电容器碳正极材料的研究进展

锂离子电容器是一种采用电容型正极材料、电池型负极材料进行组装的储能器件,结合了锂离子电池与超级电容器两者的优点,兼具高能量密度、高功率密度和长循环寿命。但是由于锂离子电容器还存在正负极动力学过程以及容量不匹配的问题,大大影响了锂离子电容器的电化学性能。通常锂离子电容器的功率密度取决于负极材料,而能量密度取决于正极材料,因此为提高锂离子电容器的能量密度,还需发展具有高比容量和高导电性的正极材料。目前,碳材料因具有低成本、来源广泛、高比表面积和丰富的孔道结构等特点,是一种极具应用潜力的电极材料。综述并分析了各种碳材料(包括活性炭、模板炭、石墨烯和生物炭等)作为锂离子电容器正极材料的电化学性能与优缺点,最后对锂离子电容器正极材料的研究提出了建议与展望。     

一种用于磷酸铁锂电极的水性黏结剂制备与性能研究

磷酸铁锂作为锂离子电池正极材料应用广泛。目前在其电极制备中仍采用PVDF油系黏结剂体系,可用于该电极的水性黏结剂仍需进一步研究。通过反应型乳化剂共聚苯乙烯（St）与丙烯酸异辛酯（2-EHA）制备了不同结构的磷酸铁锂正极水系黏结剂PSEHA,探讨了黏结剂对电池性能的影响。PSEHA黏结剂不含不饱和双键,抗氧化性好,较低的溶胀率可以有效防止过度溶胀导致的结构破坏,而反应型乳化剂可以解决乳化剂残留问题。采用所得最优结构黏结剂制备的磷酸铁锂电极表现出优异的电化学稳定性,扣式电池1 C循环100圈后容量保留率仍有96%,而SBR仅有93.9%;软包全电池在1 C倍率下循环170圈后容量保留率仍有98.9%。该新型水性黏结剂对促进磷酸铁锂水性体系制备有重要意义。     

锂离子电池硅负极粘结材料的研究进展

硅基负极材料因具有较高的理论比容量 4200 mAh/g，已成为国内外新能源锂离子电池负极材料领域研究热点课题。然而，由于硅基材料体积膨胀率高达400%，经多次充放电循环后，硅颗粒会发生破裂和粉化使其在电极基体上易脱落，从而导致电池容量衰减快、寿命短的技术缺陷。为缓解硅颗粒巨大体积变化产生的应力以及维持电极完整性，国内外科学研究者们从电池组成上出发，对活性材料、导电剂、粘结剂、电解液等进行系统研究，其中对聚合物粘结剂改性是一种实现其高寿命、抗衰减的有效手段之一。基于锂离子硅基负极材料优异特性及粘结材料的研究现状，综述了硅基负极组成、结构、性能、作用原理、分子间作用机制以及负极粘结剂的分子结构设计，探讨其对硅基锂离子电池电化学性能的影响规律，为锂离子电池硅基负极粘结材料的应用与开发提供理论和实践指导。     

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。     

锂离子电池Sn-Co合金负极材料的研究进展

锡基合金有望替代碳成为新一代高容量锂离子电池的负极材料。Sn-Co合金是研究最为广泛的锡基合金负极材料之一,但该材料存在首次不可逆容量大、循环稳定性差等问题,限制了其实际应用。Sn-Co合金的电化学性能主要受Sn/Co比例、活性材料结晶形态、颗粒尺寸和电极结构等因素影响,纳米材料可提高电极循环稳定性,但易导致较大的首次不可逆容量,而多孔结构的Sn-Co活性材料或多孔结构的电极集流体,有利于电极综合性能的提高。Sn-Co合金中引入碳可明显改善电极的循环容量和循环稳定性。同时综述了Sn-Co合金负极材料的制备方法及其优缺点,并对锡基合金负极材料的发展方向进行了展望。     

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.     

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。     

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.