Kicking the oil addiction

Few people were left unaffected by the soaring oil prices of summer 2008. Motorists were the hardest hit as the price at the pumps reached an all time high, but nobody could avoid paying more for their food as higher transport costs were passed on from the retailer to the consumer

3D lithium ion batteries—from fundamentals to fabrication

3D microbatteries are proposed as a step change in the energy and power per footprint of surface mountable rechargeable batteries for microelectromechanical systems (MEMS) and other small electronic devices. Within a battery electrode, a 3D nanoarchitecture gives mesoporosity, increasing power by reducing the length of the diffusion path; in the separator region it can form the basis of a robust but porous solid, isolating the electrodes and immobilising an otherwise fluid electrolyte. 3D microarchitecture of the whole cell allows fabrication of interdigitated or interpenetrating networks that minimise the ionic path length between the electrodes in a thick cell. This article outlines the design principles for 3D microbatteries and estimates the geometrical and physical requirements of the materials. It then gives selected examples of recent progress in the techniques available for fabrication of 3D battery structures by successive deposition of electrodes, electrolytes and current collectors onto microstructured substrates by self-assembly methods

Complex chloroplast RNA metabolism: just debugging the genetic programme?

<p>Abstract</p> <p>Background</p> <p>The gene expression system of chloroplasts is far more complex than that of their cyanobacterial progenitor. This gain in complexity affects in particular RNA metabolism, specifically the transcription and maturation of RNA. Mature chloroplast RNA is generated by a plethora of nuclear-encoded proteins acquired or recruited during plant evolution, comprising additional RNA polymerases and sigma factors, and sequence-specific RNA maturation factors promoting RNA splicing, editing, end formation and translatability. Despite years of intensive research, we still lack a comprehensive explanation for this complexity.</p> <p>Results</p> <p>We inspected the available literature and genome databases for information on components of RNA metabolism in land plant chloroplasts. In particular, new inventions of chloroplast-specific mechanisms and the expansion of some gene/protein families detected in land plants lead us to suggest that the primary function of the additional nuclear-encoded components found in chloroplasts is the transgenomic suppression of point mutations, fixation of which occurred due to an enhanced genetic drift exhibited by chloroplast genomes. We further speculate that a fast evolution of transgenomic suppressors occurred after the water-to-land transition of plants.</p> <p>Conclusion</p> <p>Our inspections indicate that several chloroplast-specific mechanisms evolved in land plants to remedy point mutations that occurred after the water-to-land transition. Thus, the complexity of chloroplast gene expression evolved to guarantee the functionality of chloroplast genetic information and may not, with some exceptions, be involved in regulatory functions.</p

Pouch-Cell Architecture Downscaled to Coin Cells for Electrochemical Characterization of Bilateral Electrodes

We suggest a new technique to assemble coin cells that allows the use of two unilateral electrodes with a bilateral electrode sandwiched between them. This method requires no unique tools or materials, and can help labs with limited resources test their electrodes in more realistic, pouch type conditions that can better showcase the capabilities of their novel research products.</p

Evaluating the Passivation Layer of Freshly Cleaved Silicon Surfaces by Binary Silane‐ based Electrolytes

The expansion of silicon anodes in lithium-ion batteries during lithiation and the resulting instability of its solid-electrolyte interphase (SEI) has been its Achilles heel for quite some time. Beyond the mechanical damage, this expansion exposes fresh elemental silicon to the electrolyte solution. The electrolyte readily decomposes on the reactive silicon surface. Researchers that test novel electrolytes find it difficult to separate which of the electrolyte components (solvent or anion) decomposes first and diagnose the respective decomposition products. Here, we utilize a straightforward test protocol that reveals which reduces first on bare silicon. We exposed four electrolyte mixtures to elemental silicon in custom made T-cells by breaking thin silicon wafers in solution. We analyze the resulting surface film layers and compare their composition to the electrolyte's performance in symmetrical lithium cells, and Si/Li cells. We found that unstable anions rather than reactive solvents lead to poor electrochemical performance

Study of Ruthenium-Contamination Effect on Oxygen Reduction Activity of Platinum-based PEMFC and DMFC Cathode Catalyst

We outline a systematic experimental and theoretical study on the influence of ruthenium contamination on the oxygen reduction activity (ORR) of a Pt/C catalyst at potentials relevant to a polymer electrolyte fuel cell cathode. A commercial Pt/C catalyst was contaminated by different amounts of ruthenium, equivalent to 0.15-4 monolayers. The resulting ruthenium-contaminated Pt/C powders were characterized by Energy–Dispersive X–ray Spectroscopy (EDS), X–ray Photoelectron Spectroscopy (XPS) and Scanning Transmission Electron Microscopy (STEM) to verify ruthenium contamination. A rotating disk electrode (RDE) technique was used to study the influence of ruthenium on oxygen reduction kinetics. Density functional theory (DFT) calculations were performed to estimate the oxygen reduction activity of the platinum surface with increasing ruthenium coverage, simulating ruthenium-contaminated Pt/C. The binding energies of O and OH on the surfaces were used for activity estimations. It was found that the specific activity of the ORR at 0.85V vs RHE exhibited a pseudo-exponential decay with increased ruthenium contamination, decreasing by ~45% already at 0.15 monolayer-equivalent contamination. The results of the DFT calculations were qualitatively in line with experimental findings, verifying the effect of O and OH binding energies and the oxophilic nature of ruthenium on ORR and the ability of the chosen approach to predict the effect of ruthenium contamination on ORR on platinum

Study of the Formation of a Solid Electrolyte Interphase (SEI) on a Silicon Nanowire Anode in Liquid Disiloxane Electrolyte with Nitrile End Groups for Lithium‐Ion Batteries

The chemical compatibility of the various compounds and elements used in lithium‐based batteries dictates their safe operation parameters and performance. The lithium salt Li‐bis(trifluoromethanesulfonyl)imide (LiTFSI) has many advantages over the common LiPF6 salt as it does not react with water impurities to form, for example, hydrofluoric acid. To further accommodate safe‐operation chemistry, we use a non‐volatile disiloxane‐based solvent 1,3‐bis(cyanopropyl)tetramethyldisiloxane (TmdSx‐CN). This is a liquid disiloxane functionalized with terminal nitrile groups. In this paper, we report on the electrochemical characterization and the composition of the solid electrolyte interphase (SEI) of 1 mol kg−1 LiTFSI dissolved in TmdSx‐CN in silicon‐lithium batteries. Specifically, we study the SEI formation on silicon nanowire anodes and its composition by several ex‐situ surface techniques (XPS, SEM), and in‐situ via polarization modulation infrared reflectance absorption spectroscopy (PM‐IRRAS). We evaluate the potential application of TmdSx‐CN to silicon‐lithium batteries and conclude that the addition of fluoroethylene carbonate (FEC) at low concentrations (10 wt %) is essential to the formation of an effective SEI. We anticipate that our study will encourage the investigation, design and use of siloxane‐based solvents as safer alternatives to common solvents used in Li‐ion batteries, and specifically as candidate solvents in Li‐metal and silicon‐anode based batteries