【按】一个美国的同事告诉我，你们的最新 Nano Lett 论文被权威替代能源网站 Green Car Congress 专题报道了，仔细浏览一下，看到报道全文，又仔细看了一下读者的评论，发现大家非常关注，并给予积极的评价。在哈佛最大的感受，学术讨论氛围比较好，大家乐于学术讨论，尽管都喜欢听好话和赞美的话，但批评性和建设性的建议还是很受欢迎的，对研究质量的提高也非常有用。欢迎各位同行和朋友加强交流和讨论，提高研究水平，共同进步，把辛苦争取到的国家经费发挥积极的作用！！ New cost-saving method to synthesize vanadium oxide nanowires for Li-ion electrodes; Improved capacity and cycling stability 23 October 2010 (a, b) Schematic illustration of formation of the ultralong hierarchical vanadium oxide nanowires during annealing. (c) Side view of two ultralong hierarchical vanadium oxide nanowires near each other. (d) Self-aggregation of short vanadium oxide nanorods. Credit: ACS, Mai et al. Click to enlarge. A team from Harvard University and the Wuhan University of Technology (China) has synthesized novel ultralong hierarchical vanadium oxide (V 2 O 5 nanowires from attached single-crystalline vanadium oxide nanorods via electrospinning combined with annealing and using low-cost starting materials. Compared with self-aggregated short nanorods synthesized by hydrothermal methods, the ultralong hierarchical vanadium oxide nanowires exhibit much higher capacity and improved cycling stability, the researchers report in a paper published online 18 October in the ACS journal Nano Letters . ...in the ordinary batteries, owing to the high surface energy, nanomaterials are often self-aggregated, which reduces the effective contact areas of active materials, conductive additives, and electrolyte. How to keep the effective contact areas large and fully realize the advantage of active materials at nanometer scale is still a challenge and of great importance. Hierarchical nanostructured materials such as hollow nanospheres, porous nanostructures, nanotubes, nanowire-on-nanowire structures, and kinked nanowires, etc., can ensure the surface remains uncovered to keep the effective contact areas large even if a small amount of inevitable self-aggregation occurs. There has been much interest in electrospinning and/or electrochemistry of vanadium oxide nanowires/nanorods because nanostructured vanadium/molybdenum oxides with a typical layed structure have the potential to offer high capacities for lithium ion batteries. ...Compared with previous studies on electrospinning of vanadium oxide nanowires by using expensive organic vanadium oxide isopropoxide as the raw materials, we successfully synthesized vanadium oxide nanowires via electrospinning by using inorganic ammonium metavanadate as precursor, which is cost-saving and more suitable for industrial production of lithium batteries. Moreover, the as-prepared ultralong hierarchical vanadium oxide nanowires were found to offer high charge/discharge capacities and improved cycling stability. Mai et al. The initial and 50 th discharge capacities of the ultralong hierarchical vanadium oxide nanowire cathodes are up to 390 and 201 mAh/g when the lithium ion battery cycled between 1.75 and 4.0 V. When the battery was cycled between 2.0 and 4.0 V, the initial and 50 th discharge capacities of the nanowire cathodes are 275 and 187 mAh/g. Self-aggregation of the unique nanorod-in-nanowire structures has been greatly reduced, the authors suggest, because of the attachment of nanorods in the ultralong nanowires, which can keep the effective contact areas of active materials, conductive additives, and electrolyte large and fully realize the advantage of nanomaterial-based cathodes. The high performance of our batteries is attributed to several reasons. We deduce that self-aggregation of the ultralong hierarchical vanadium oxide nanowires can be effectively prevented, which keeps the surface area large to fully realize the advantage of nanostructured materials. Furthermore, after annealing at 480 C, the vanadium oxide nanorods of high crystallinity in the nanowires make the active materials stable during cycling...Compared with other vanadium oxide nanorods by combining electrospinning with hydrothermal treatment or annealing, our ultralong hierarchical vanadium oxide nanowires have higher specific capacity and better cycling capability. ...The nanorod-in-nanowire described in this paper is a unique structure that will probably have potential applications in chemical power sources, sensors, and other nanodevices. Mai et al. Resources Liqiang Mai, Lin Xu, Chunhua Han, Xu Xu, Yanzhu Luo, Shiyong Zhao, and Yunlong Zhao (2010) Electrospun Ultralong Hierarchical Vanadium Oxide Nanowires with High Performance for Lithium Ion Batteries. Nano Lett. , Article ASAP doi: 10.1021/nl103343w October 23, 2010 in Batteries | Permalink | Comments (7) | TrackBack (0) TrackBack TrackBack URL for this entry: http://www.typepad.com/services/trackback/6a00d8341c4fbe53ef01348867ad46970c Listed below are links to weblogs that reference New cost-saving method to synthesize vanadium oxide nanowires for Li-ion electrodes; Improved capacity and cycling stability : Comments This sounds exciting. 390 and 201 mAh/g when the lithium ion battery cycled between 1.75 and 4.0 V. I'm assuming the discharge curve is typical of other batteries, meaning the voltage and current stay pretty high until it's almost discharged, and then they drop of rapidly. In that case we might conservatively expect an average voltage of 3 V and gravimetric capacity of 300 mAh/g. Multiplying these together gives 900 wh/g (0.9 kWh/kg) energy density for the cathode. This is 80 or 90% higher than LiCoO2 or LiFePO4 according to the chart on http://en.wikipedia.org/wiki/Lithium-ion Thew self-aggregation of carbon nanotubes in the Contour/MIT cathodes was also a problem, but they found an electorostatic method to prevent clumping and maintaining porosity. This and the electrospinning/annealing processes seem very promising. Posted by: Zhukova | October 23, 2010 at 06:35 AM I remember seeing claims ten years ago that nano-tech would change the world. It looks like that may turn out to be true. Posted by: DaveD | October 23, 2010 at 09:37 AM The exciting thing is that this appears to be a manufacturing breakthrough. We've seen many examples of how nanorods, nanotudes, nanoparticles, etc can absorb more lithium in the laboratory. But we haven't seen as much news on manufacturing techniques that can make a battery cheaply (and without expensive heavy metals like cobalt). Posted by: Zhukova | October 23, 2010 at 10:27 AM Good point. It's all about the cost to manufacture the materials now and these techniques will allow them to become widely used. Posted by: DaveD | October 23, 2010 at 10:51 AM This could have good potential for future higher performance batteries if patent restriction doesn't keep it from being manufactured and marketed. Wonder how many similar patents were bought out by oil firms. Posted by: HarveyD | October 23, 2010 at 10:53 AM A cathode that has 80% more capacity would make more than 80% for the battery. That's because the cathode takes about 40% of the mass of the battery, while the anode is about 20%. So for a 100g battery, the new cathode would weigh 22 grams instead of 40 g. Using Dr. Qui's silicone nanowire anode means a reduction to about 3 grams from 20. That's more than 50% reduction combined. The separator and packaging could be reduced by 50% too, which is 20 g. So the whole battery now weighs only 45g. This is more than doubling the energy density per kg compared to a LiFeO2. Posted by: Zhukova | October 23, 2010 at 04:21 PM Yeah, that is why I'm always excited to see advances in cathodes. They lag far behind anodes and make up a greater percentage of the total weight/volume. Very encouraging. Posted by: DaveD | October 23, 2010 at 06:04 PM Verify your Comment Previewing your Comment Posted by: | This is only a preview. Your comment has not yet been posted. 窗体顶端 窗体底端 Your comment could not be posted. Error type: Your comment has been posted. Post another comment The letters and numbers you entered did not match the image. Please try again. As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments. Having trouble reading this image? View an alternate. 窗体顶端 窗体底端 窗体顶端 Post a comment This weblog only allows comments from registered users. To comment, please Sign In . You are currently signed in as (nobody). 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纳米高引论文与高产科学家 纳米类权威刊物《Nano Letters》创刊十年之际，基于该刊数据库评出了纳米高引论文与纳米高产科学家，分别如下： 纳米高引论文 10 Most-Cited Articles 2001-2009 Probing the Cytotoxicity of Semiconductor Quantum Dots Austin M. Derfus, Warren C. W. Chan, and Sangeeta N. Bhatia Nano Letters , 2004 , 4 (1), pp 1118. DOI: 10.1021/nl0347334 High Performance Silicon Nanowire Field Effect Transistors Yi Cui, Zhaohui Zhong, Deli Wang, Wayne U. Wang, and Charles M. Lieber Nano Letters , 2003 , 3 (2), pp 149152. DOI: 10.1021/nl025875l Carbon Nanotube Inter- and Intramolecular Logic Gates V. Derycke, R. Martel, J. Appenzeller, and Ph. Avouris Nano Letters , 2001 , 1 (9), pp 453456. DOI: 10.1021/nl015606f Highly Luminescent Monodisperse CdSe and CdSe/ZnS Nanocrystals Synthesized in a HexadecylamineTrioctylphosphine OxideTrioctylphospine Mixture Dmitri V. Talapin, Andrey L. Rogach, Andreas Kornowski, Markus Haase, and Horst Weller Nano Letters , 2001 , 1 (4), pp 207211. DOI: 10.1021/nl0155126 Block-by-Block Growth of Single-Crystalline Si/SiGe Superlattice Nanowires Yiying Wu, Rong Fan, and Peidong Yang Nano Letters , 2002 , 2 (2), pp 8386. DOI: 10.1021/nl0156888 High Weight Fraction Surfactant Solubilization of Single-Wall Carbon Nanotubes in Water M. F. Islam, E. Rojas, D. M. Bergey, A. T. Johnson, and A. G. Yodh Nano Letters , 2003 , 3 (2), pp 269273. DOI: 10.1021/nl025924u Individually Suspended Single-Walled Carbon Nanotubes in Various Surfactants Judith Schmidt and Yeshayahu Talmon Nano Letters , 2003 , 3 (10), pp 13791382. DOI: 10.1021/nl034524j Spontaneous Polarization-Induced Nanohelixes, Nanosprings, and Nanorings of Piezoelectric Nanobelts Xiang Yang Kong and Zhong Lin Wang Nano Letters , 2003 , 3 (12), pp 16251631. DOI: 10.1021/nl034463p Large-Scale Hexagonal-Patterned Growth of Aligned ZnO Nanorods for Nano-optoelectronics and Nanosensor Arrays Xudong Wang,Xudong Wang, Christopher J. Summers, and Zhong Lin Wang Nano Letters , 2004 , 4 (3), pp 423426. DOI: 10.1021/nl035102c Hierarchical ZnO Nanostructures Jing Yu Lao, Jian Guo Wen, and Zhi Feng Ren Nano Letters , 2002 , 2 (11), pp 12871291. DOI: 10.1021/nl025753t 纳米高产科学家 Most Prolific Authors 2001-2009 Younan N. Xia Washington University in St. Louis Zhong Lin Wang Georgia Institute of Technology Lars Samuelson Lund University Charles M. Lieber Harvard University A. Paul Alivisatos University of California, Berkeley Peidong Yang University of California, Berkeley Phaedon Avouris T.J. Watson Research Center, IBM Naomi J. Halas Rice University Pulickel Ajayan Rice University Chad Mirkin Northwestern University Cees Dekker Kavli Institute of Nanoscience, Delft University of Technology Nicholas Kotov University of Michigan
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