A C15 AB(2) Laves-type Ti0.15Zr0.85La0.03Ni1.2Mn0.7V0.12Fe0.12 alloy was prepared by arc melting and annealing. Phase-structural composition, microstructure, hydrogen absorption-desorption properties, thermodynamic and electrochemical performances were characterized by X-ray diffraction, scanning electron microscopy, hydrogen absorption-desorption measurements and electrochemical characterization and were related to the use of the alloys as metal hydride battery anodes. The alloy contains a C15 FCC intermetallic compound as the main phase and a LaNi secondary phase as the minor constituent (similar to 1 wt%). During the electrochemical tests, the anode electrodes quickly, after just a few activation cycles, reached a maximum discharge capacity. This was related to the catalytic effect of the La-rich secondary phase which acted as a catalyst of hydrogen absorption-desorption. Annealing resulted in increase of the maximum discharge capacity from 345 mAh/g for the as cast alloy to 370 mAh/g. Furthermore, the annealed alloy showed a better high rate dischargeability and a higher cyclic stability. After 100 cycles with 100% DOD at discharge current density of 1C, the discharge capacity of the annealed alloy was very high, at a level of 90% of the initial capacity. The rates of hydrogen diffusion have been characterized by Potentiostatic Intermittent Titration Technique and Electrochemical Impedance Spectroscopy. With increasing an extent of transformation into the hydride, the H diffusion rate in the bulk of the alloy particles decreased. The maximum value of D-H measured by PITT for the annealed alloy was observed for the nearly fully discharged electrode, (SOC 2%). (C) 2019 Published by Elsevier B.V.

The increasing demand for high capacity yet safe storage of renewable energy calls for the development of all-solid-state batteries. A major hurdle in this development is the identification of new suitable types of solid-state electrolytes. Nanoconfined lithium borohydride is a solid-state electrolyte candidate due to its high lithium-ion mobility at ambient temperatures. The origin of the high lithium-ion mobility is not fully understood, however. We studied nanocomposites of lithium borohydride and nanoporous silica Santa Barbara Amorphous-15 (SBA-15) with different pore sizes, using H-1, Li-6,Li-7, and B-11 solid-state NMR at various temperatures, to get in-depth insights into the phase behavior and ion dynamics of lithium borohydride in the silica pores. The results allow us to formulate a detailed dynamic model for lithium borohydride confined in SBA-15; bulklike LiBH4 is separated from the pore walls by an amorphous, highly dynamic LiBH4 fraction displaying both Li+ and BH4- diffusion even at ambient temperatures. As shown by B-11 temperature-jump exchange NMR, this dynamic fraction increases as a function of temperature. Li+ exchange between the bulklike and "dynamic" LiBH4 fraction is slow at ambient temperatures, but at elevated temperatures (>= 90 degrees C), above the phase transition of the bulklike fraction, lithium ions rapidly diffuse through both LiBH4 fractions and exchange between these confined fractions at rates approaching the megahertz time scale.

Thinning of boiler tubing is one of common failure mechanism of coal-based boiler unit. An ultrasonic thickness testing (UT) is typically used to determine the state of boiler tube thickness and is done during a yearly overhaul. The usefulness of thickness data can be problematic due to some fluctuation and irregularities in the data. In the present work, UT data from 4 years inspection will be analyzed with the aim to understand the fundamental mechanism for thinning of the superheater tube. Some part of the UT data is analyzed to obtain the thinning rate of the superheater tube. The thinning trend is the basis for predicting the value of thickness and compared with actual measurement values. The predicted and actual values were tested with statistical operation to observe the significant difference between both values and also the quality of prediction.

Lead-acid battery is widely used as automotive starting, lighting, and ignition (SLI) batteries. Due to economic of the production and rather simple manufacturing process, the lead-acid battery remains as a feasible type of battery for renewable energy storage application. However, the cycle life of battery is limited to several hundreds of cycles depends on operational conditions. The aim of the present work was to study the effect of depth of discharge (DoD) on the cycle life of a battery which is relevant for battery in renewable energy applications. The battery samples used in the present work were prepared from commercial SLI battery. The sample was cycled in 2 electrode systems at constant current charging and discharging procedure in an Autolab PGSTAT 302 N at different DoD, i.e. 40%, 60%, and 80% for 80 cycles. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) were used to characterize active materials after the cycle life test. The cycle test showed a significant formation of lead sulfate (PbSO4) on the negative and positive electrode and the highest level was found at 80% DoD. The sulfation decreased as DoD was reduced. Excessive lead sulfate (PbSO4) formation was found on the negative electrode at all the DoD regimes. This result indicates that decreasing cycle life of valve regulated lead acid (VRLA) battery is mostly caused by sulfation on the negative electrode.

Designing new functional materials is crucial for the development of efficient energy storage and conversion devices such as all solid‐state batteries. LiBH4 is a promising solid electrolyte for Li‐ion batteries. It displays high lithium mobility, although only above 110 °C at which a transition to a high temperature hexagonal structure occurs. Herein, it is shown that confining LiBH4 in the pores of ordered mesoporous silica scaffolds leads to high Li+ conductivity (0.1 mS cm−1) at room temperature. This is a surprisingly high value, especially given that the nanocomposites comprise 42 vol% of SiO2. Solid state 7Li NMR confirmed that the high conductivity can be attributed to a very high Li+ mobility in the solid phase at room temperature. Confinement of LiBH4 in the pores leads also to a lower solid‐solid phase transition temperature than for bulk LiBH4. However, the high ionic mobility is associated with a fraction of the confined borohydride that shows no phase transition, and most likely located close to the interface with the SiO2 pore walls. These results point to a new strategy to design low‐temperature ion conducting solids for application in all solid‐state lithium ion batteries, which could enable safe use of Li‐metal anodes.

Influences of fluorine containing compounds TiF4 and ZrF4 on hydrogen sorption properties of LiBH4 have been investigated. Thermovolumetric measurements, titration, and XRD technique were used to characterize the samples. The results demonstrated a pronounced beneficial effect of both ZrF4 and TiF4 on the sorption properties of modified LiBH4. After hydrogenation at 400 degrees C and 80 bar, formation of modified LiBH4 was observed as a consequence of F dissolution in LiH (LiH1-zFz). Adding TiF4 and ZrF4 to LiBH4 has been found to modify both thermodynamic and kinetic properties.