1,173 research outputs found

    Fast microwave-assisted synthesis of Li-stuffed garnets and insights into Li diffusion from muon spin spectroscopy

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    Lithium-stuffed garnets attract huge attention due to their outstanding potential as solid-state electrolytes for lithium batteries. However, there exists a persistent challenge in the reliable synthesis of these complex functional oxides together with a lack of complete understanding of the lithium-ion diffusion mechanisms in these important materials. Addressing these issues is critical to realizing the application of garnet materials as electrolytes in all solid-state lithium-ion batteries. In this work, a cubic phase garnet of nominal composition Li6.5Al0.25La2.92Zr2O12 is synthesized through a microwave-assisted solid-state route for the first time, reducing considerably the reaction times and heating temperatures. Lithium-ion diffusion behavior is investigated by electrochemical impedance spectroscopy (EIS) and state-of-art muon spin relaxation (μSR) spectroscopy, displaying activation energies of 0.55 ± 0.03 eV and 0.19 ± 0.01 eV respectively. This difference arises from the high inter-grain resistance, which contributes to the total resistance in EIS measurements. In contrast, μSR acts as a local probe providing insights on the order of the lattice, giving an estimated value of 4.62 × 10−11 cm2 s−1 for the lithium diffusion coefficient. These results demonstrate the potential of this lithium-stuffed garnet as a solid-state electrolyte for all-solid state lithium-ion batteries, an area of growing interest in the energy storage community

    Microwave-assisted synthesis and electrochemical evaluation of VO2 (B) nanostructures

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    Understanding how intercalation materials change during electrochemical operation is paramount to optimizing their behaviour and function and in situ characterization methods allow us to observe these changes without sample destruction. Here we first report the improved intercalation properties of bronze phase vanadium dioxide VO2 (B) prepared by a microwave-assisted route which exhibits a larger electrochemical capacity (232 mAh g-1) compared with VO2 (B) prepared by a solvothermal route (197 mAh g-1). These electrochemical differences have also been followed using in situ X-ray absorption spectroscopy allowing us to follow oxidation state changes as they occur during battery operation

    Recent Decisions

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    Comments on recent decisions by Larry E. Corr, John J. Malik, Richard E. Shipman, Paul R. Jackiewicz, Mark S. Tolle, Harry L. Buch, Stanley R. Herrlinger, John W, Houck, Donald J. Prebenda, Donald W, Bebenek, Michael C. Dionise, and J. Robert Geiman

    Spectral absorption of biomass burning aerosol determined from retrieved single scattering albedo during ARCTAS

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    Actinic flux, as well as aerosol chemical and optical properties, were measured aboard the NASA DC-8 aircraft during the ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) mission in Spring and Summer 2008. These measurements were used in a radiative transfer code to retrieve spectral (350-550 nm) aerosol single scattering albedo (SSA) for biomass burning plumes encountered on 17 April and 29 June. Retrieved SSA values were subsequently used to calculate the absorption Angstrom exponent (AAE) over the 350-500 nm range. Both plumes exhibited enhanced spectral absorption with AAE values that exceeded 1 (6.78 ± 0.38 for 17 April and 3.34 ± 0.11 for 29 June). This enhanced absorption was primarily due to organic aerosol (OA) which contributed significantly to total absorption at all wavelengths for both 17 April (57.7%) and 29 June (56.2%). OA contributions to absorption were greater at UV wavelengths than at visible wavelengths for both cases. Differences in AAE values between the two cases were attributed to differences in plume age and thus to differences in the ratio of OA and black carbon (BC) concentrations. However, notable differences between AAE values calculated for the OA (AAEOA) for 17 April (11.15 ± 0.59) and 29 June (4.94 ± 0.19) suggested differences in the plume AAE values might also be due to differences in organic aerosol composition. The 17 April OA was much more oxidized than the 29 June OA as denoted by a higher oxidation state value for 17 April (+0.16 vs. -0.32). Differences in the AAEOA, as well as the overall AAE, were thus also possibly due to oxidation of biomass burning primary organic aerosol in the 17 April plume that resulted in the formation of OA with a greater spectral-dependence of absorption. © Author(s) 2012. CC Attribution 3.0 License
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