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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Insertion Mechanism of a Poly(ethylene oxide)-poly(butylene oxide) Block Copolymer into a DPPC Monolayer

Interactions between amphiphilic block copolymers and lipids are of medical interest for applications such as drug delivery and the restoration of damaged cell membranes. A series of monodisperse poly(ethylene oxide)-poly(butylene oxide) (EOBO) block copolymers were obtained with two ratios of hydrophilic/hydrophobic block lengths. We have explored the surface activity of EOBO at a clean interface and under 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers as a simple cell membrane model. At the same subphase concentration, EOBO achieved higher equilibrium surface pressures under DPPC compared to a bare interface, and the surface activity was improved with longer poly(butylene oxide) blocks. Further investigation of the DPPC/EOBO monolayers showed that combined films exhibited similar surface rheology compared to pure DPPC at the same surface pressures. DPPC/EOBO phase separation was observed in fluorescently doped monolayers, and within the liquid-expanded liquid-condensed coexistence region for DPPC, EOBO did not drastically alter the liquid-condensed domain shapes. Grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XRR) quantitatively confirmed that the lattice spacings and tilt of DPPC in lipid-rich regions of the monolayer were nearly equivalent to those of a pure DPPC monolayer at the same surface pressures.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Highly Reversible Mg Insertion in Nanostructured Bi for Mg Ion Batteries

Rechargeable magnesium batteries have attracted wide attention for energy storage. Currently, most studies focus on Mg metal as the anode, but this approach is still limited by the properties of the electrolyte and poor control of the Mg plating/stripping processes.1,2 Here we report the synthesis and application of Bi nanotubes as a high performance anode material for rechargeable Mg ion batteries. The nanostructured Bi anode delivers a high reversible specific capacity (350 mAh/gBi, or 3430 mAh/cm3 Bi), excellent stability, and high columbic efficiency (95 % initial and very close to 100% afterwards). The good performance is attributed to the unique properties of in-situ formed, interconnected nanoporous bismuth. Such nanostructures can effectively accommodate the large volume change without losing electric contact and significantly reduce diffusion length for Mg2+. Significantly, the nanostructured Bi anode can be used with conventional electrolytes which will open new opportunities to study Mg ion battery chemistry and further improve the properties. The performance and the stability of a full cell Mg ion battery have been demonstrated with conventional electrolytes. This work suggests that other high energy density alloy compounds may also be considered for Mg-ion chemistry for high capacity electrode materials.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2015

Realizing the Full Potential of Insertion Anodes for Mg-ion Batteries Through the Nano-Structuring of Sn

For next-generation rechargeable batteries, magnesium is of great interest as an alternative to Lithium due to its relative abundance, low toxicity, and bivalent charge (3833 mAh/cm3 and 2205 mAh/g). However, Mg-ion batteries face unique challenges related to the formation of anode passivation layers, anode-electrolyte-cathode incompatibilities, slow solid-state Mg2+ diffusion, and ion trapping. Using analytical (scanning) transmission electron microscopy ((S)TEM) and ab initio modeling, we have investigated Mg2+ intercalation and extraction mechanisms in β-SnSb alloy nanoparticles (NPs). During the first several charge-discharge cycles, the SnSb particles irreversibly break down into a network of pure-Sn and Sb-rich sub-particles, as Mg-ions replace Sn ions in the SnSb lattice. Once the morphology has stabilized, the small Sn NPs (< 20 nm) are responsible for the majority of reversible storage capacity, while the Sb-rich particles trap substitutional-Mg atoms in the lattice and are significantly less active. This result strongly indicates that pure-Sn nanoparticles on a graphene support can act as a high capacity anode for Mg-ion batteries.

Environmental Molecular Sciences Laboratory↗