Lithium-Ion Battery Aspects on Fires in Electrified Vehicles on the Basis of Experimental Abuse Tests

Safety issues concerning the use of large lithium-ion (Li-ion) batteries in electrified vehicles are discussed based on the abuse test results of Li-ion cells together with safety devices for cells. The presented abuse tests are: overcharge, short circuit, propane fire test and external heating test (oven). It was found that in a fire, cells with higher state of charge (SOC) gave a higher heat release rate (HRR), while the total heat release (THR) had a lower correlation with SOC. One fire test resulted in a hazardous projectile from a cylindrical cell. In the fire tests, toxic gas emissions of hydrogen fluoride (HF) were measured for 100%, 50% and 0% SOC

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

Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr 4 NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC), 3.17wt.% propylene carbonate (PC), 19.0 wt.% of Pr 4 NI, and 1.9wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 x 10 -3 S cm -1. The dye-sensitized solar cell (DSSC) fabricated with this electrolyte exhibits an efficiency of 3.5% with.. SC of 7.38mAcm -2,.. OC of 0.72V, and fill factor of 0.66. When various amounts of lithium iodide (LiI) were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr 4 NI : LiI is 2 : 1. This cell has.. SC,.. OC and fill factor of 7.25mAcm -2, 0.77V and 0.67, respectively

Anionic Graft Copolymers Containing Poly(ethylene oxide)

Anionic graft copolymers were prepared through ring-opening anhydride reactions between poly(ethylene oxide) monomethyl ethers (MPEG) and copolymers of maleic anhydride and styrene (SMA), methyl vinyl ether (MEMA) and ethylene (EMA), respectively. The carboxylic acid groups in the graft copolymers were neutralized with KOH, and films were prepared by solution casting. The materials were characterized by FTIR, NMR and DSC. Ionic conductivity and electrical relaxation have been studied as well. The EMA-MPEG 2000 graft copolymer showed the highest conductivity, sigma = 3 x 10(-5) S cm(-1) at 80 degrees C

Lithium-ion Batteries used in Electrified Vehicles – General Risk Assessment and Construction Guidelines from a Fire and Gas Release Perspective

This report presents a general and broad risk assessment and construction guidelines for lithium-ion battery systems used in electrified vehicles, from the perspectives of fire and gas release. General types of Li-ion battery systems and electrified vehicles, ranging from light to heavy-duty vehicles, are included. The findings in the report are based on results obtained in the project “Safer battery systems in electrified vehicles – develop knowledge, design and requirements to secure a broad introduction of electrified vehicles”, conducted between the years 2012-2017 and lead by RISE Research Institutes of Sweden. The guidelines focus on both how to design the battery system and on how to integrate and place the battery in the vehicle in order to increase the safety in terms or fire and gas release.Safer battery systems in electrified vehicles – develop knowledge, design and requirements to secure a broad introduction of electrified vehicle

Ionic Conductivity and Dielectric Properties of Poly(ethylene oxide) Graft Copolymers End-capped with Sulfonic Acid

Both anions and cations are mobile and carry the electrical charge in most polymer electrolytes. A single ion conductor with purely cationic conduction can be realized by incorporation of the anion into the polymer chain. In order to obtain pure lithium ion conductors we prepared two types of graft copolymers, namely poly(amide 12-graft-ethylene oxide) and poly(ethylene-co-vinyl alcohol-gr aft-ethylene oxide), respectively, and end-capped the poly(ethylene oxide) grafts with sulfonic acid groups. Lithium salts of the graft copolymers were made by neutralizing the sulfonic acid groups with lithium hydroxide. Films of the neutralized polymers were prepared by solution casting. The thermal properties of the films were evaluated from DSC measurements. Complex impedance spectroscopy gave information on the ionic conductivity and dielectric relaxations. The highest conductivity, at 80 degrees C, 2*10(-5) S/cm was obtained for poly(amide 12-graft-ethylene oxide)