Electrochemical properties of arlysilanes - new paper in Electrochemistry Communications; Hanzu and co-workers throw light on the fascinating properties of 11 arylsilanes, 2 of them synthesized for the first time. Link: paper EC
Li-bearing argyrodites play an important role as solid electrolytes for next-generation batteries. In a new publication, which appeared in RSC's PCCP, we report in detail on the complex interplay of local structures and ion dynamics. Importantly, also for the poor ion conductor Li6PS5I we found rapid ion dynamics on a local lenght scale. Link: paper in PCCP
Li ion diffusivity is, in general, faster in glassy materials than in the crystalline counterparts. In particular, this relation holds for compounds with the same chemical composition. If a glassy sample is mechanically treated in a high-energy ball mill a material is obtained with a lower diffusivity as compared to that in the original sample. Obviously, structural relaxation is responsible for the decrease observed. Via modulus spectroscopy we followed the change in electrical relaxation and identified two distinct relaxation rates which we attribute to the situation in the unmilled glass and to Li species being already influenced by mechanical treatment. Link: paper in JPCC
Singlet oxygen (1O2) causes a major fraction of parasitic chemistry during cycling of non-aqueous alkali metal-O2 batteries and also contributes to interfacial reactivity of transition-metal oxide intercalation compounds. Yet DABCOnium, the mono alkylated form of 1,4-diazabicyclo[2.2.2]octane (DABCO), is introduced in Angewandte Chemie as an efficient 1O2 quencher with an unusually high oxidative stability of ~4.2 V vs. Li/Li+. Previously known quenchers are strongly Lewis basic amines with too low oxidative stability. It is an ionic liquid, non-volatile, highly soluble in the electrolyte, and stable against superoxide and peroxide. The electrochemical stability covers the required range for metal-O2 batteries and greatly reduces 1O2 related parasitic chemistry as demonstrated for the Li-O2 cell.
A joint undertaking of Korean, US American and Austrian researchers revealed singlet oxygen as the main reason for the gradual deactivation of redox mediators in lithium-oxygen batteries in an article in Nature Communications.
Non-aqueous lithium-oxygen batteries cycle by forming lithium peroxide during discharge and oxidizing it during recharge. The significant problem of oxidizing the solid insulating lithium peroxide can greatly be facilitated by incorporating redox mediators that shuttle electron-holes between the porous substrate and lithium peroxide. Redox mediator stability is thus key for energy efficiency, reversibility, and cycle life. It is shown that organic redox mediators are predominantly decomposed by singlet oxygen that forms during cycling. Their reaction with superoxide, previously assumed to mainly trigger their degradation, peroxide, and dioxygen, is orders of magnitude slower in comparison. Redox mediators must thus be designed for stability against singlet oxygen.
Researchers of the National Institute of Chemistry, Ljubljana and ICTM underlined in a recent publication in Polymer the unique mechanical properties of emulsion templated macroporous polymer foams consisting of poly(dicyclopentadiene). The recent work deals with the influence of surfactant loading on strengths and toughness of this kind of porous matter which can be considered as the strongest and toughest macroporous polymer foams available up to now.
Since the pioneering work of Liang in 1973 nano- or mesostructured composites consiting of an insulator and an ionically conducting phase act as model systems helpful to understand interfacial transport properties. (7)Li and (19)F NMR revealed details of the diffusion mechanism in LiF:alumina composites. Link to J. Phys. Chem. C
In a collaborative publication of researchers of the Chinese Academy of Sciences, the South China Normal University, Austrian company Anton Paar GmbH and the Trimmel group non-fullerene polymer solar cells with a high efficiency of 13.3% were disclosed in Chemistry of Materials. The success is based on properly selecting and processing donor–acceptor pairs with suitable electronic properties and complementary optical absorption.
A new paper has been published by the Rettenwander group about single-crystal X-ray diffraction to study the nature of Li+/H+ exchange in cubic Li7La3Zr2O12 (LLZO) garnets. On the basis of the proton concentration change over time (3 years), a spherical diffusion model was used to estimate the proton diffusion coefficient to be of the order of 2 × 10–17 m2/s. This diffusion coefficient is high enough to have a significant impact on both the cell performance and safety when LLZO is used as a protecting layer for Li metal anodes in Li-ion batteries that rely on liquid electrolytes. Link to JPCC.
We seek to fill a PhD student position (30 h/week) in our research group in the course of March 2019. Topics: Solid-State Chemistry and Electrochemistry, new solid electrolytes, safety of all-solid-state batteries, spectroscopic methods (NMR, impedance spectroscopy, GPCL, GITT, etc.) You have a M.Sc. degree, Diploma or equivalent in Inorganic/Analytical Chemistry, Physical Chemistry or related areas, strong interest in Solid-State Physical Chemistry and application-oriented research. Contact: wilkeningnoSpam@tugraz.at or hanzunoSpam@tugraz.at
A new paper about 2D F anion diffusion in nanocrystalline RbSn2F5 that has been prepared by a mechanochemical approach is out. We used broadband conductivity spectroscopy and nuclear magnetic relaxation to show that F preferably diffuses between the Rb-Sn layers. Analyzing the NMR relaxation rates with a spectral density function developed for 2D diffusion yields a consistent picture about F dynamics. This spectral density function has been introduced by P. M. Richards in 1978. Link to PCCP.
...has been published by Thomas Rath et al. Dr. Rath assembled an interdisciplinary team for realizing his latest paper on ligand-free preparation of polymer/CuInS2 nanocrystal films and employing this strategy for improving the performance of solar cells. The work appeared as open access article in Journal of Materials Chemistry C.
The Trimmel group realized an new synthesis route towards copper indium sulfide (CuInS2) nanocrystals with a size of 3–4 nm and a chalcopyrite crystal structure starting from copper and indium xanthates as precursors in a hot injection synthesis performed at a temperature of 200 °C and used the material as acceptor in polymer/nanocrystal bulk heterojunction solar cells. The work has been published in New Journal of Chemistry as an open access arcticle.