石墨碎锂电池负极材料包覆炭化的研究

以煤沥青为包覆材料,煤油为溶剂,对除杂整形后的石墨碎进行包覆炭化改性处理,得到的样品进行物理特性分析,并组装电池进行电性能测试。结果表明,随着包覆量的增加,颗粒平均粒度也增加,但增加幅度较小,为1~2μm;样品的比表面积随着包覆量的增加而降低,经过沥青包覆和石墨化后,样品的比表面积由6.715 m~2/g大幅度降低到1.618 m~2/g;振实密度随着包覆量的增加而提高,最高可达1.05 g/cm~3。经过包覆后样品的层间距d002有所增加。包覆后样品的表面逐渐平滑,棱角少,并且炭化后的沥青炭填充了部分石墨颗粒的孔隙,降低了比表面积,未包覆的样品表面粗糙,有较多的沟壑、孔隙。样品随着包覆量的增加,首次放电容量和首次充放电效率都呈现出增加的趋势,首次放电容量由316.56 m A·h/g升至330.82 m A·h/g,首次放电效率由89.09%升至94.45%,当沥青包覆量达10%时,首次放电容量和首次充放电效率均达最大。     

精制石油焦基负极材料的电化学性能研究

以精制石油焦为原料,经球磨、炭化和石墨化制备负极材料,并组装成扣式电池.考察影响电化学性能的石墨化关键性能,包括表面形貌、比表面积、粒度分布、石墨化度、元素组成等,进行充放电、循环伏安、交流阻抗测试.结果表明,首次嵌锂容量为349.2 mAh/g,首次库伦效率为78％;500次循环后,容量上升为440.6 mAh/g,...     

硅碳负极材料的合成研究

以光伏产业废硅粉为原料,采用球磨工艺, CMC为碳源,得到了最优的碳包覆比例,得到了一种碳包覆硅碳负极材料。借助扫描电镜(SEM)和模拟电池测试等方法,对硅碳复合材料的结构、形貌和电化学性能进行表征。结果表明,采用2.5%CMC添加量的碳包覆材料性能较优,其首次放电比容量为850.3 mAh/g,20次放电容量还保持690.8 mAh/g,为首次放电容量的81.24%mAh/g。     

改性天然鳞片石墨锂离子电池负极材料的研究

对粒径为12μm的天然鳞片石墨进行表面碳包覆改性,并对包覆前后样品的微观结构和电化学性能进行了研究。结果表明:包覆改性提高了天然石墨的振实密度、表面形貌和电化学性能,在0.1 C、0.2 C、0.5 C、1 C、2 C、5 C和10 C倍率下,对应的可逆容量分别为368.6 mAh/g、362.6 mAh/g、353.8 mAh/g、340.6 mAh/g、298.6 mAh/g、228.2 mAh/g和150.2 mAh/g,相对于天然石墨,可逆容量分别提高了6.2 mAh/g、20.9 mAh/g、31.6 mAh/g、42.1 mAh/g、52.4 mAh/g、80.0 mAh/g和58.0 mAh/g,碳包覆小粒径天然石墨表现出的良好的倍率性能,有望应用于电动车用锂离子电池中。     

Li4Ti5O12@C复合材料的制备及其性质研究

本文以葡萄糖为碳源,采用原位复合法制备锂离子电池复合负极材料Li4Ti5O12@C,同时探讨了不同碳包覆量对Li4Ti5O12的影响。通过X-射线衍射和扫描电子显微镜对合成出的材料结构及表面形貌进行表征,采用恒电流充放电和电化学阻抗等技术对其进行电化学性能测试。结果表明：碳包覆量为3 %的Li4Ti5O12颗粒均匀且电化学性能最好。在0.5 C下,首次放电比容量为185.9 mAh/g,循环50次后,其放电比容量仍为161.5 mAh/g。在2.0 C下,首次放电比容量为99.9 mAh/g,材料表现出优良的电化学性能。     

威宁无烟煤基石墨制备及其电化学性能研究

以贵州威宁无烟煤为原料，通过物理提纯可制备低灰(1.60%)无烟煤，探究了不同石墨化温度对无烟煤基石墨微观结构的影响，并进一步考察了威宁无烟煤石墨化样品用作锂离子电池负极材料的电化学性能。研究表明：随热处理终温的升高，煤基石墨样品石墨化度和石墨晶体结构有序度逐渐提高，在2 800℃下所得煤基石墨石墨化度可达96.99%。煤基石墨的首次可逆容量和库伦效率随石墨化终温升高而逐渐提高，煤基石墨WN-2800在0.1C(1C=372 mAh/g)电流密度下首次可逆容量和库伦效率分别可达293.5 mAh/g、86.8%。煤基石墨WN-2800在1C电流密度下经过100次循环后，可逆容量为241.0 mAh/g,且库伦效率始终接近100%。煤基石墨WN-2800表现出较优异的综合电化学性能。本研究表明，威宁无烟煤可作为制备高性能煤基人造石墨的优质原料。     

羧甲基纤维素包覆天然石墨性能的研究

本实验研究了羧甲基纤维素(CMC)包覆对天然石墨电化学性能的影响。通过XRD、恒电流充放电测试手段研究了不同包覆量对该复合材料结构和电化学性能的影响。结果表明:羧甲基纤维素裂解炭对天然石墨有较好的包覆作用,并且能够有效的阻止石墨在充放电过程中发生层状剥落现象,从而有效的提高复合炭材料的循环稳定性,其中5%树脂包覆量的复合材料在循环50次之后可逆容量是310.9 mAh.g-1,比天然石墨高50 mAh.g-1,并保持了首次可逆容量的97.1%。     

不同沥青包覆球形天然石墨负极材料结构和性能研究

通过选用3种不同软化点及组分含量的石油沥青,采用固相包覆法对球形天然石墨进行包覆,考察了软化点不同的沥青对包覆后球形天然石墨负极材料的结构和电化学性能的影响。结果表明:高软化点及高TI和QI组分含量的沥青,炭化过程中分子分解聚合反应更为平缓,挥发分气体逸出少,具有更高残炭率,包覆炭化后能在球形天然石墨表面形成致密无定形碳层,改性后的石墨负极材料具有更高的可逆容量和更好的循环性能,经过高软化点沥青包覆后的球形天然石墨样品,常温1 C下循环200次容量保持率由55.8%提升至96%以上。     

聚乙烯吡咯烷酮包覆硫/碳复合材料的制备及其电化学性能

采用液相化学沉积法,并引入聚乙烯吡咯烷酮（PVP）制备得到聚乙烯吡咯烷酮包覆硫/碳复合材料。采用热重分析（TGA）、扫描电子显微镜（SEM）、X射线衍射（XRD）、恒流充放电和循环伏安（CV）表征其物化性能和电化学性能,结果表明,聚乙烯吡咯烷酮可有效提高硫/碳复合材料的电化学性能。0.35 C充放电时,所得聚乙烯吡咯烷酮包覆硫/碳复合材料首次放电比容量达到1 415.3 mAh/g(按单质硫的质量计算),120次后比容量保留为903.3 mAh/g,容量保持率为63.8%;2 C充放电时,首次放电比容量可达到904 mAh/g,200次后比容量仍能保持在486.8 mAh/g。     

ZnF2包覆对锂离子电池正极材料LiNi0.5Mn1.5O4的性能影响

本文用溶胶凝胶法制备了LiNi0.5Mn1.5O4正极材料,然后用ZnF2对其进行表面包覆。XRD测试表明,包覆处理没有影响材料的晶体结构,EDS、SEM和TEM测试表明,2wt%ZnF2在LiNi0.5Mn1.5O4表面形成了约7 nm厚的均匀包覆层。对未包覆、1wt%、2wt%、3wt%包覆后的材料进行电化学性能测试对比,发现包覆后都能减弱电解液与基体间的相互作用,较大地稳定电极表面,提高了材料的电化学性能。其中,2wt%ZnF2包覆样品表现出最佳的电化学性能,0.2 C倍率下循环200圈后,其放电比容量维持在109 mAh/g,容量保持率为79.7%;在10 C时,放电比容量依然高达102.1 mAh/g;5 C高倍率下循环500圈后,放电比容量维持在94.2 mAh/g,容量保持率为85.6%。     

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。