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Dirlam, Philip T.,Park, Jungjin,Simmonds, Adam G.,Domanik, Kenneth,Arrington, Clay B.,Schaefer, Jennifer L.,Oleshko, Vladimir P.,Kleine, Tristan S.,Char, Kookheon,Glass, Richard S.,Soles, Christopher American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.21
<P>The practical implementation of Li-S technology has been hindered by short cycle life and poor rate capability owing to deleterious effects resulting from the varied solubilities of different Li polysulfide redox products. Here, we report the preparation and utilization of composites with a sulfur-rich matrix and molybdenum disulfide (MoS2) particulate inclusions as Li-S cathode materials with the capability to mitigate the dissolution of the Li polysulfide redox products via the MoS2 inclusions acting as 'polysulfide anchors'. In situ composite formation was completed via a facile, one-pot method with commercially available starting materials. The composites were afforded by first dispersing MoS2 directly in liquid elemental sulfur (S-8) with sequential polymerization of the sulfur phase via thermal ring opening polymerization or copolymerization via inverse vulcanization. For the practical utility of this system to be highlighted, it was demonstrated, that the composite formation methodology was amenable to larger scale processes with composites easily prepared in 100 g batches. Cathodes fabricated with the high sulfur content composites as the active material afforded Li-S cells that exhibited extended cycle lifetimes of up to 1000 cycles with low capacity decay (0.07% per cycle) and demonstrated exceptional rate capability with the delivery of reversible capacity up to 500 mAh/g at 5 C.</P>
The Icebreaker Life Mission to Mars: A Search for Biomolecular Evidence for Life
McKay, Christopher P.,Stoker, Carol R.,Glass, Brian J.,Davé,, Arwen I.,Davila, Alfonso F.,Heldmann, Jennifer L.,Marinova, Margarita M.,Fairen, Alberto G.,Quinn, Richard C.,Zacny, Kris A.,Paulsen Mary Ann Liebert 2013 Astrobiology Vol.13 No.4
<P>The search for evidence of life on Mars is the primary motivation for the exploration of that planet. The results from previous missions, and the Phoenix mission in particular, indicate that the ice-cemented ground in the north polar plains is likely to be the most recently habitable place that is currently known on Mars. The near-surface ice likely provided adequate water activity during periods of high obliquity, ? 5 Myr ago. Carbon dioxide and nitrogen are present in the atmosphere, and nitrates may be present in the soil. Perchlorate in the soil together with iron in basaltic rock provides a possible energy source for life. Furthermore, the presence of organics must once again be considered, as the results of the Viking GCMS are now suspect given the discovery of the thermally reactive perchlorate. Ground ice may provide a way to preserve organic molecules for extended periods of time, especially organic biomarkers. The Mars Icebreaker Life mission focuses on the following science goals: (1) Search for specific biomolecules that would be conclusive evidence of life. (2) Perform a general search for organic molecules in the ground ice. (3) Determine the processes of ground ice formation and the role of liquid water. (4) Understand the mechanical properties of the martian polar ice-cemented soil. (5) Assess the recent habitability of the environment with respect to required elements to support life, energy sources, and possible toxic elements. (6) Compare the elemental composition of the northern plains with midlatitude sites. The Icebreaker Life payload has been designed around the Phoenix spacecraft and is targeted to a site near the Phoenix landing site. However, the Icebreaker payload could be supported on other Mars landing systems. Preliminary studies of the SpaceX Dragon lander show that it could support the Icebreaker payload for a landing either at the Phoenix site or at midlatitudes. Duplicate samples could be cached as a target for possible return by a Mars Sample Return mission. If the samples were shown to contain organic biomarkers, interest in returning them to Earth would be high.</P>
Chung, Woo Jin,Simmonds, Adam G.,Griebel, Jared J.,Kim, Eui Tae,Suh, Hyo Seon,Shim, In‐,Bo,Glass, Richard S.,Loy, Douglas A.,Theato, Patrick,Sung, Yung‐,Eun,Char, Kookheon,Pyun, Jeffrey WILEY‐VCH Verlag 2011 Angewandte Chemie Vol.123 No.48
<P><B><I>Der Einsatz von elementarem Schwefel</I></B> als Reaktionsmedium für die Herstellung von Goldnanopartikeln und vulkanisierten Nanokompositen wird in der Zuschrift von J. Pyun et al. auf Seite 11 611 ff. beschrieben. Flüssiger Schwefel dient in diesem System als Lösungsmittel, Reduktionsmittel und Stabilisator für die Herstellung von Goldkolloiden. Potenziell nutzbarer elementarer Schwefel fällt in riesigen Mengen beim Raffinieren von Erdöl an.</P>
Elemental Sulfur as a Reactive Medium for Gold Nanoparticles and Nanocomposite Materials
Chung, Woo Jin,Simmonds, Adam G.,Griebel, Jared J.,Kim, Eui Tae,Suh, Hyo Seon,Shim, In‐,Bo,Glass, Richard S.,Loy, Douglas A.,Theato, Patrick,Sung, Yung‐,Eun,Char, Kookheon,Pyun, Jeffrey WILEY‐VCH Verlag 2011 Angewandte Chemie Vol.123 No.48
<P><B>Schwefelgelb:</B> Elementarer Schwefel wird als unkonventionelles Medium für die Synthese und Stabilisierung von kolloidalem Gold genutzt. In diesem System erfüllt Schwefel viele Funktionen, wie die Sulfurierung von PPh<SUB>3</SUB> und die Solubilisierung und Reduktion von Au<SUP>I</SUP>‐Vorstufen zu Au‐Nanopartikeln (NPs; siehe Bild). Die Vulkanisation von Au‐haltigen Schwefeldispersionen erfordert vernetzte Nanokomposite, die mit TEM, XRD, XPS und Raman‐Spektroskopie nachgewiesen wurden.</P>
Oleshko, Vladimir P.,Kim, Jenny,Schaefer, Jennifer L.,Hudson, Steven D.,Soles, Christopher L.,Simmonds, Adam G.,Griebel, Jared J.,Glass, Richard S.,Char, Kookheon,Pyun, Jeffrey Cambridge University Press (Materials Research Soc 2015 MRS Communications Vol.5 No.3
<▼1><B>Abstract</B><P/></▼1><▼2><P>Poly[sulfur-random-1,3-diisopropenylbenzene (DIB)] copolymers synthesized via inverse vulcanization form electrochemically active polymers used as cathodes for high-energy density Li-S batteries, capable of enhanced capacity retention (1005 mAh/g at 100 cycles) and lifetimes of over 500 cycles. In this prospective, we demonstrate how analytical electron microscopy can be employed as a powerful tool to explore the origins of the enhanced capacity retention. We analyze morphological and compositional features when the copolymers, with DIB contents up to 50% by mass, are blended with carbon nanoparticles. Replacing the elemental sulfur with the copolymers improves the compatibility and interfacial contact between active sulfur compounds and conductive carbons. There also appears to be improvements of the cathode mechanical stability that leads to less cracking but preserving porosity. This compatibilization scheme through stabilized organosulfur copolymers represents an alternative strategy to the nanoscale encapsulation schemes which are often used to improve the cycle life in high-energy density Li-S batteries.</P></▼2>