天然微晶石墨提纯工艺及可逆储锂性能

天然微晶石墨含量丰富,晶粒微小,表现为各向同性,是制备锂离子电池负极材料的极好原料,但其纯度不高,利用盐酸和氟硅酸对浮选后微晶石墨进行混酸提纯处理.实验结果表明:当液固比为2:1、HF体积分数为50％、提纯时间为3 h、提纯温度为70℃时固定碳含量最高,达99％;结合XRD、SEM、EDS和Raman分析可知,混酸提纯后微晶石墨纯度提高,层间距变小,结晶度提高;提纯后的微晶石墨首次放电比容量为778.9 mAh/g,首次库伦效率增加到61.3％,循环性能、充放电效率和倍率性能均提高,阻抗值均降低.     

微晶石墨提纯工艺研究进展

石墨是高新技术发展和国民经济建设的重要材料,也是一种具有战略性意义的矿产资源,在航空航天、医疗、冶金、机械等行业有着广泛的应用。在锂电池行业,石墨是目前主要的负极材料,并且占据了锂电负极材料市场的绝大部分。然而,天然石墨往往含有各种杂质,必须经过提纯才能达到工业生产的标准,目前国内工业技术水平相较于国外还有一定差距。本文重点介绍了微晶石墨提纯的主要方法,包括浮选法、高温法、碱酸法、氢氟酸法和氯化焙烧法,并比较了各种方法的优缺点,为微晶石墨提纯工艺的发展提供了思路和见解。     

专利介绍

专利名称：微晶石墨提纯辅料的配方 本发明公开了一种高纯度的微晶石墨提纯辅料的配方。技术方案是：微晶石墨与氢氟酸、硫酸溶液的重量配比分别是：30％～35％、20％～30％、35％～45％,其中氢氟酸浓度为40％、密度1．13;硫酸浓度为98％、密度1．84。     

氢氧化钙沉淀法处理微晶石墨纯化酸性含氟废水正交试验

采用正交试验对氢氧化钙沉淀法处理微晶石墨纯化酸性含氟废水进行了研究。考察了氢氧化钙用量、p H值和搅拌时间对废水中F-质量浓度的影响,从而确定氢氧化钙处理微晶石墨纯化酸性含氟废水最佳工艺参数及影响废水处理的主要因素。结果表明,在氢氧化钙沉淀法处理微晶石墨纯化后酸性含氟废水过程中,氢氧化钙用量对F-质量浓度影响显著,p H值和搅拌时间对F-质量浓度影响相对较小。本试验最佳水平组合为:每100m L含氟废水中加入5.39g氢氧化钙,在p H值为8的条件下搅拌10min,经沉淀后过滤处理得到低氟浓度废水,该水平组合下F-质量浓度由7900mg/L降为5.31mg/L。     

混酸提纯工艺对微晶石墨结构及电性能的影响

<正>为进一步提高微晶石墨纯度,将乳化煤油浮选后的微晶石墨经过多次HF-HCl混酸法提纯,分别制备锂离子电池负极材料。利用X射线衍射(XRD)、拉曼光谱(Raman)和扫描电镜(SEM)等方法分析了酸洗前后微晶石墨的结构特点和微观形貌,并通过恒电流充放电、交流阻抗等手段测试了样品的电化学性能。结果表明:乳化煤油浮选和HF-HCl酸洗两步法     

微晶石墨与无烟煤浮沉特性研究

对内蒙古某无烟煤共伴生型微晶石墨采用酸法脱灰,根据浮沉法研究了微晶石墨与无烟煤的浮沉分离密度及不同密度级产物的产率分布,采用X射线衍射和拉曼光谱特征分析了浮沉分离后微晶石墨与无烟煤的矿物组成及拉曼特征.结果表明:以拉曼光谱参数AD/(AD +AG)值表征无烟煤基微晶石墨中无烟煤含量,并将AD/(AD+AG)值与浮沉试验中浮物累积产率比对,二者变化趋势具有较好的一致性,但受解离度影响.     

天然微晶石墨加工及应用技术现状

天然微晶石墨晶体微小,每个石墨颗粒由许多微晶无序堆积,呈现出各向同性,在锂离子动力电池用负极材料等领域有重要潜在应用价值.近年来,天然微晶石墨的战略地位日益提高,已成为科研界、产业界和金融界的热点.本文概述了天然微晶石墨的加工和应用技术现状,并对其发展趋势进行了展望.     

微晶石墨作为阳极材料对二次锂离子电池电化学性能的影响

利用Li－C实验电池,得到了微晶石墨（无定形石墨）作阳极材料时,其成分、粒度对锂离子电池电化学性能的影响。结果表明,微晶石墨在0．7V左右的不可逆容量与石墨颗粒的粒度和纯度无关;随着杂质含量的减少,可逆容量略有增加,但不可逆插入容量明显减少;杂质的成分与含量对微晶石墨的循环性能的影响不大;其可逆容量与不可逆插入容量都随着石墨粒度减小而增大;颗粒大小对其循环性能的影响不大。     

煤系中隐晶石墨开发的初步研究

在煤系地层隐晶石墨的加工工艺中 ,采用酸碱法 ,可使隐晶石墨品位提纯到 99.5 %～ 99.9% ;利用超声波粉碎隐晶石墨 ,可获得粒经 <0 5 μm的含量占 99.9% ;用微波法合成了金属及其卤化物隐晶石墨夹层复合物和氟化隐晶石墨 ;研制出了隐晶石墨节能抗磨剂等生产工艺 ,在进一步研究后 ,将可实现工业化应用     

石墨纯化技术研究分析

对比分析浮选法、酸碱法、氢氟酸法、氯化焙烧法以及高温提纯等纯化石墨技术的优缺点,提出采用将氯化焙烧法和高温纯化结合的高温氟利昂纯化技术来纯化石墨.高温氟利昂纯化工艺,选取氟利昂作为纯化气体,在密封真空腔室中加热至2200℃以上进行纯化.通过尾气处理装置,有效解决了尾气带来的环保问题,成功应用于生产.辉光放电质谱(GDM...     

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。