柠檬酸包覆钛酸锂负极材料的改性研究

采用柠檬酸(C6H8O7·H2O)作碳源制备Li4Ti5O12/C复合材料,利用X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)研究了柠檬酸添加量对材料结构和形貌的影响。研究结果表明:添加不同量的柠檬酸,所制备的样品均为尖晶石型结构。随着柠檬酸添加量的增加,材料颗粒粒径逐渐增大,分布更加均匀,团聚也逐渐加剧。在1.0~2.5V的电压范围内,对样品进行恒流充放电测试,柠檬酸(C6H8O7·H2O)的添加量为6%时,制备的Li4Ti5O12/C复合材料具有最佳的电化学性能,0.2C和1C的放电比容量分别为171.3m Ah/g和165.4m Ah/g。     

锂离子电池正极材料Li2Mn0.95Mg0.05SiO4的合成和电化学性能

以Li2SiO3、Mn(CH3COO)2·4H2O和Mg(CH3COO)2·4H2O为原料,采用高温固相反应法成功合成出Li2Mn0.95Mg0.05SiO4锂离子电池正极材料.采用XRD、扫描电镜等技术分析了合成粉末的相组成、结构和微观形貌,利用电池测试仪测试了正极材料的电化学性能.研究结果表明,固相合成的粉末主相为Li2Mn0.95Mg0.05SiO4,同时存在少量的杂质,产物表面形貌、粒度均与未掺杂样品类似,二者均为非球形颗粒,颗粒尺寸约为100～500 nm.电化学测试结果表明,Mg掺杂后,正极材料的可逆容量和循环寿命都得到提高.正极材料电化学性能提高的机理在于Mg掺杂稳定了Li2MnSiO4正极材料的结构.     

碳源对碳热法制备LiFePO4/C复合电极材料性能的影响

以廉价的Fe2O3为铁源,(NH4)H2PO4为磷源,Li2CO3为锂源,分别以乙炔黑、葡萄糖、PEG6000为还原剂和碳源,采用碳热还原法制备了LiFePO4/C复合材料。X射线衍射(XRD)分析表明用三种碳源都合成了橄榄石结构的LiFePO4。扫描电子显微镜(SEM)分析显示,以PEG6000为碳源合成的LiFePO4/C复合材料粒径较小,较均匀,且有较好的碳包覆。以充放电曲线、循环性能和交流阻抗等测试研究了材料的电化学性能,结果表明,以PEG6000为碳源合成的材料的电化学性能较好,0.1C、1C下首次放点比容量分别为144.7 mAh/g、132 mAh/g。     

不同碳源合成Li2MnSiO4／C正极材料的电化学性能

采用溶胶一凝胶法合成Li2MnSiO4并以葡萄糖、己二酸和蔗糖为碳源合成Li2MnSiO4／C材料,对其进行XRD物相分析和SEM形貌分析。对合成出的Li2MnSiO4及Li2MnSiO4／C电极进行了充放电和电化学阻抗谱（EIS）测试。充放电结果表明碳包覆可以提高Li2MnSiO4放电容量,EIS结果说明,Li2MnSiO4／C能够减少电荷传递电阻,增加锂离子在颗粒内部的扩散速率,从而提高材料的电化学性能。     

LiNO3-TiO2-尿素体系燃烧合成锂离子电池负极材料Li4Ti5O12及电化学性能

以纳米TiO2和LiNO3为原料,尿素为燃料,燃烧法合成了锂离子电池负极材料Li4Ti5O12. 利用XRD、SEM和恒电流充放电、循环伏安和交流阻抗对其进行表征. 结果表明,预设炉温850℃,尿素与锂摩尔比1,焙烧8 h,制备得到平均粒径小于500 nm、粒度分布均匀的纯相尖晶石型结构Li4Ti5O12,并具有良好的电化学性能,具有1.5 V充放电平台,在0.1 C倍率下(1 C=170 mA·h/g),其首次充放电容量达到168 mA·h/g,经过100次循环后放电比容量仍有162 mA·h/g,容量保持率96.4%.     

高库仑效率的锂离子电池负极材料炭包覆锂化钛酸锂

利用纳米TiO2颗粒和Li2CO3为原料,分别在不添加及添加中间相沥青的情况下通过固相反应制备出Li4Ti5O12及炭包覆的锂化钛酸锂Li4+x Ti5O12/C。Li4Ti5O12颗粒尺寸在0.5～3μm之间,而Li4+x Ti5O12/C颗粒尺寸比较均匀,在200～500 nm之间,且颗粒表面包覆了一层厚度约2 nm的炭层。充放电研究表明,Li4Ti5O12的可逆容量较低,而Li4+x Ti5O12/C则具有非常高的可逆容量、循环稳定性及容量保持率。同时,Li4+x Ti5O12/C可提供Li+补偿首次不可逆容量损失,导致首次库仑效率超过100%。Li4+x Ti5O12/C中预储锂量随碳源量的增加而增加,在碳源量5%条件下制得的Li4+x Ti5O12/C的首次脱锂容量超过嵌锂容量24.2 mAh·g-1。Li4+x Ti5O12/C有望消除锂离子全电池的首次不可逆容量损失并提高其容量。     

高库仑效率的锂离子电池负极材料炭包覆锂化钛酸锂

利用纳米TiO2颗粒和Li2CO3为原料,分别在不添加及添加中间相沥青的情况下通过固相反应制备出Li4Ti5O12及炭包覆的锂化钛酸锂Li4+x Ti5O12/C。Li4Ti5O12颗粒尺寸在0.5～3μm之间,而Li4+x Ti5O12/C颗粒尺寸比较均匀,在200～500 nm之间,且颗粒表面包覆了一层厚度约2 nm的炭层。充放电研究表明,Li4Ti5O12的可逆容量较低,而Li4+x Ti5O12/C则具有非常高的可逆容量、循环稳定性及容量保持率。同时,Li4+x Ti5O12/C可提供Li+补偿首次不可逆容量损失,导致首次库仑效率超过100%。Li4+x Ti5O12/C中预储锂量随碳源量的增加而增加,在碳源量5%条件下制得的Li4+x Ti5O12/C的首次脱锂容量超过嵌锂容量24.2 mAh·g-1。Li4+x Ti5O12/C有望消除锂离子全电池的首次不可逆容量损失并提高其容量。     

改进固相法合成LiNixCoyMn1-x-yO2正极材料及性能研究

采用同相法制备正极材料LiNi1/3Co1/3Mn1/3O2,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)/透射电镜(TEM)分析材料的结构和形貌特征,用LAND电池测试系统测试材料的电化学性能(充放电容量和循环性能等).以LiOH·H2O,H2C2O4·2H2O,Ni(AC)2·4H2O,Co(AC)2·4H2O和Mn(AC)2·4H2O为原料,采用固相法在不同煅烧温度和煅烧时间下制备的层状正极材料LiNi1/3Co1/3Mn1/3O2具有典型的α-NaFeO2型层状结构特征,晶型结构完整.电化学性能测试结果表明,在850℃下保温15 h合成的正极材料电化学性能最优,在电流密度为120 mA/g、充放电电压在2.75～4.5 V时,经30次循环后放电比容量为163.5 mA·h/g,容量保持率为94%;50次循环后为157.2 mA·h/g,容量保持率为90.8%.     

锂离子电池正极材料Li3V2[(PO4)1-xFx]3/C的合成及性能表征

以LiH2PO4、LiF和V2O5为原料,蔗糖为还原剂,用碳热还原法合成了Li3V2[(PO4)1-xFx]3/C(x=0、0.02、0.05、0.08、0.10和0.15),并用X射线衍射、Fourier变换红外光谱、循环伏安、交流阻抗谱和恒流充放电技术研究了F-掺杂对材料结构和电化学性能的影响.结果表明:F-掺杂Li3V2(PO4)3/C与纯Li3V2(PO4)3/C均为单斜结构,但少量的F-掺杂可提高电极反应可逆程度和电导率,降低电荷传递阻抗;在所得的F-掺杂材料中,Li3V2[(PO4)0.95F0.05]3/C具有较好的电化学性能.在3.0～4.2V (vs.Li/Li+)循环时,电极的0.5C放电容量为124.4 mA·h/g,50次循环后容量保持率为98.5％,15C下的放电容量为84.7mA·h/g,50次循环后容量保持率为97.4％,而Li3V2(PO4)3/C的仅为59.2 mA·h/g和89.0％.     

LiMg_(0.1)Fe_(0.9)PO_4/C的合成与电化学性能研究

为了改善磷酸铁锂的电化学性能,以Li2CO3,FeC2O4.2H2O,(MgCO3)4.Mg(OH)2.5H2O,(NH4)2HPO4为原料,葡萄糖为碳源,用高温固相反应法合成了锂离子电池正极材料LiMg0.1Fe0.9PO4/C,用电化学方法测试了LiMg0.1Fe0.9PO4/C与LiFePO4/C的充放电性能和循环稳定性,利用X射线衍射、扫描电镜等表征了镁离子掺杂对磷酸铁锂结构和表面形貌的影响。实验结果表明:LiMg0.1Fe0.9PO4/C具有单一的橄榄石结构,且是由粒径为200~500 nm的颗粒组成,具有良好的电化学性能和循环稳定性能,镁离子的掺杂使磷酸铁锂具有更好的导电性,在0.1C下,10个循环后放电比容量为142.4 mA.h/g。     

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。