Influence of binders and solvents on stability of Ru/RuOx nanoparticles on ITO nanocrystals as Li–O2 battery cathodes

Fundamental research on Li–O2 batteries remains critical, and the nature of the reactions and stability are paramount for realising the promise of the Li–O2 system. We report that indium tin oxide (ITO) nanocrystals with supported 1–2 nm oxygen evolution reaction (OER) catalyst Ru/RuOx nanoparticles (NPs) demonstrate efficient OER processes, reduce the recharge overpotential of the cell significantly and maintain catalytic activity to promote a consistent cycling discharge potential in Li–O2 cells even when the ITO support nanocrystals deteriorate from the very first cycle. The Ru/RuOx nanoparticles lower the charge overpotential compared with those for ITO and carbon-only cathodes and have the greatest effect in DMSO electrolytes with a solution-processable F-free carboxymethyl cellulose (CMC) binder (<3.5 V) instead of polyvinylidene fluoride (PVDF). The Ru/RuOx/ITO nanocrystalline materials in DMSO provide efficient Li2O2 decomposition from within the cathode during cycling. We demonstrate that the ITO is actually unstable from the first cycle and is modified by chemical etching, but the Ru/RuOx NPs remain effective OER catalysts for Li2O2 during cycling. The CMC binders avoid PVDF-based side-reactions and improve the cyclability. The deterioration of the ITO nanocrystals is mitigated significantly in cathodes with a CMC binder, and the cells show good cycle life. In mixed DMSO–EMITFSI [EMITFSI=1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide] ionic liquid electrolytes, the Ru/RuOx/ITO materials in Li–O2 cells cycle very well and maintain a consistently very low charge overpotential of 0.5–0.8 V

Contrast Enhancement in Polymeric Electrochromic Devices Encompassing Room Temperatu re Ionic Liquids

We report the preparation and spectro - electrochemical characterization of electrochromic devices (ECD) combining inkjet - printed WO 3 as cathode and electro - deposited V 2 O 5 as anode. ECD were prepared for the first time with an optimized formulation of gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) encompassing the Room Temperature Ionic Liquid (RTIL, 1 - Ethyl - 3 - methylimidazolium bis(trifluoromethylsulfonyl)imide) as solvent. The UV - VIS spectrum of ECD was recorded at different potentials during Li + insertion and de - insertion; additionally the Percent Trasmittance (T%) of ECD vs. time was investigated during repeated bleaching and coloring cycles allowing thus the esti mation of switching times and device stability. Due to the lower ionic conductivity and the apparent superior solvent permeability within WO 3 active layer, RTIL containing ECD showed slower switching times, but higher contrast with respect to the similar o nes with EC/DEC as solvent. These results indicate that the ECD containing environment - friendly RTIL electrolytes are suitable for applications requiring high contrast, high safety and moderately fast switching times

Sealed gas recombining lead-acid batteries. Part I: A simple theoretical approach

The solution of the differential equations expressing the gas material balance in a sealed lead—acid cell led us to propose a simple experimental method to evaluate the parameters controlling the cell behaviour both in dynamic and in steady state conditions