Overcurrent Abuse of Primary Prismatic Zinc–Air Battery Cells Studying Air Supply Effects on Performance and Safety Shut-Down

Overcurrent abuse has been performed on commercial 48 Ah primary prismatic zinc (Zn)–Air battery cells with full air supply as well as with shut-off air supply. Compared to other battery technologies, e.g., lithium-ion batteries, metal–air batteries offer the possibility to physically stop the battery operation by stopping its air supply, thus offering an additional protection against severe battery damage in the case of, e.g., an accidental short circuit. This method may also reduce the electrical hazard in a larger battery system since, by stopping the air supply, the voltage can be brought to zero while maintaining the energy capacity of the battery. Measurements of overdischarge currents and current cut-off by suffocation have been performed to assess the safety of this type of Zn–air battery. The time to get to zero battery voltage is shown to mainly be determined by the volume of air trapped in the cell

Diatom frustules enhancing the efficiency of gel polymer electrolyte based dye-sensitized solar cells with multilayer photoelectrodes

The incorporation of nanostructures that improve light scattering and dye adsorption has been suggested for dye-sensitized solar cells (DSSCs), but the manufacture of photonic and nanostructured materials with the desired properties is not an easy task. In nature, however, the process of light-harvesting for photosynthesis has, in some cases, evolved structures with remarkable wavelength-sensitive light-trapping properties. The present work is focused on enhancing the efficiency of quasi solid-state DSSCs by capitalizing on the light trapping properties of diatom frustules since they provide complex 3-dimensional structures for scattering and trapping light. This study reports a promising approach to prepare TiO2 nanocrystal (14 nm) based photo-electrodes by utilizing the waveguiding and photon localization effects of nanostructured diatom frustules for enhancing light harvesting without deteriorating the electron conduction. Single and double-layered photo-electrodes were prepared with different frustule/nanocrystal combinations and conformations on transparent conductive oxide substrates. This study clearly reports impressive efficiency and short circuit current density enhancements of about 35% and 39%, respectively, due to the incorporation of diatom frustules extracted from a ubiquitous species. The SEM images obtained in this work reveal that the produced thin films had a remarkable surface coverage of evenly distributed frustules within the TiO2 nanoparticle layer. To the best of our knowledge, this study reports the first quasi solid-state DSSC based on a photo-electrode with incorporated bio-formed nanostructures

Dielectric and Conductivity Studies of Polymer Electrolytes

Dielectric and conductivity studies has been performed in order to study the microscopic structure and dynamics of ion conducting polymers. The investigated systems are various salts, e.g. LiCF3SO3, dissolved in poly(ethylene glycol), poly(propylene glycol) or copolymers which partly consists of these polymers. The ionic conductivity has been measured over a wide range of concentrations. The results show similar behaviour to traditional liquid solvents featuring low permittivity. The dielectric measurements show a rapid increase in the static relative permittivity which may be attributed to the formation of ion pairs. The values of the static relative permittivity for the solution is used in a thermodynamic treatment for estimating the fractions of dissociated ions and ions associated into pairs, triplets, quadrupoles and hexapoles. The calculations show that the fraction of dissociated ions increases with increasing concentration of salt, if the static permittivity of the solution, and not the solvent is used. The dielectric measurements show also a dispersion at about 1 MHz for NH4CF3SO3, dissolved in poly(propylene glycol) at room temperature. It is argued that ion pairs should be the cause of this dielectric loss and that the corresponding frequency might serve as a probe for the local flexibility of the polymer chain segments. It may also be an alternative way to estimate the mobility of the charge carriers

Ionic conductivity enhancement in PEO:CuSCN solid polymer electrolyte by the incorporation of nickel-chloride

\ua9 2015 Elsevier B.V. All rights reserved. Copper-ion based solid polymer electrolytes exhibit interesting electrochemical properties, environmental stability and lower fabrication cost compared to lithium ion based systems. Although, poly(ethylene oxide)(PEO)-based solid polymer electrolytes have been extensively studied, those incorporating copper salts have not been explored much. One major drawback in these electrolytes is the low ionic conductivity at room temperature. In this work, we attempted to enhance the ionic conductivity of PEO9CuSCN polymer electrolyte by the incorporation of NiCl2. Incorporation of 10 wt% NiCl2 showed the highest conductivity enhancement with almost two orders of magnitude increase. The ionic conductivity value at 30 \ub0C increased from 3.1 7 10- 9 S cm- 1 for the NiCl2-free electrolyte to 1.8 7 10- 7 S cm- 1 for the 10 wt% NiCl2 incorporated electrolyte. This was associated with a significant reduction in Tg by about 30 \ub0C from - 53 \ub0C for PEO9 CuSCN to - 83 \ub0C for PEO9 CuSCN + 10 wt% NiCl2, indicating an increased segmental flexibility of the polymer chains for NiCl2 added electrolyte

H-2/Pt/Ce0.9Gd0.1O1.95/Pt/O-2 fuel cell operated in the intermediate temperature range 500-700 degrees C

Ce0.9Gd0.1O1.95 (GCO), is one of the potential candidate electrolytes for intermediate temperature Solid Oxide Fuel Cells (ITSOFC). GCO has high oxide ion conductivity in the intermediate temperature range (500 - 700 degrees C) compared to other C1-yGdyO2-2/y compositions and the Gd3+ ion is the most appropriate dopant material compared to other rare earth materials such as Sm3+, Y3+, Zr3+, etc. Our results show that the fuel cell H-2/Pt/Ce0.9Gd0.1O1.95/O-2 operated in the temperature range 500 - 700 degrees C gives the maximum power densities 0.0049 W/cm(2) at 500 degrees C and 0.0126 W/cm(2) at 650 degrees C for cell voltages 0.6275 V and 0.6278 V, respectively, where the electrolyte was kept in 5% H-2(+ Argon) for 12 hours before use in the fuel cell. Maximum power densities are 0.0038 W/cm(2) at 500 degrees C and 0.0270 W/cm(2) at 650 degrees C for cell voltages 0.5986 and 0.5913 V, respectively, where the electrolyte was kept in 2 % O-2(+ Argon) for 12 hours before use in the fuel cell

Dielectric relaxation studies in Cs2SO4

Dielectric measurements of Cs2SO4 show a distinct relaxation at low frequencies at several isotherms (

Dielectric relaxation studies in Cs2SO4

Dielectric measurements of Cs2SO4 show a distinct relaxation at low frequencies at several isotherms (