Lithium sulfur (Li–S) batteries have great potential as a successor to Li-ion batteries, but their commercialization has been complicated by a multitude of issues stemming from their complex multiphase chemistry. In situ X-ray tomography investigations enable direct observations to be made about a battery, providing unprecedented insight into the microstructural evolution of the sulfur cathode and shedding light on the reaction kinetics of the sulfur phase. Here, for the first time, the morphology of a sulfur cathode was visualized in 3D as a function of state of charge at high temporal and spatial resolution. While elemental sulfur was originally well-dispersed throughout the uncycled cathode, subsequent charging resulted in the formation of sulfur clusters along preferred orthogonal orientations in the cathode. The electrical conductivity of the cathode was found not to be rate-limiting, suggesting the need to optimize the loading of conductive carbon additives. The carbon and binder domain and surrounding bulk pore phase were visualized in the in situ cell, and contrast changes within both phases were successfully extracted. The applications of this technique are not limited to microstructural and morphological characterization, and the volumetric data can serve as a valuable input for true 3D computational modeling of Li–S batteries.

Silyl glyoxylates are proposed here as a new class of high performance type I photoinitiators for free radical polymerization under air or in laminate (e.g., (meth)­acrylates) upon exposure to different near-UV (at 395 nm; at 405 nm) and blue (at 477 nm) LEDs. The new proposed photoinitiators can also be used in the presence of additives that can enhance their initiating ability: an iodonium salt and an amine or a phosphine. The silyl glyoxylate-based photoinitiating systems exhibit excellent polymerization performances upon blue LED light (at 477 nm) with exceptional bleaching properties compared to camphorquinone (CQ)-based systems. This can be highly worthwhile for the preparation of colorless polymers upon visible light. Real-time Fourier transform infrared spectroscopy (RT-FTIR) experiments are used to monitor the polymerization profiles. The involved chemical mechanisms are investigated by fluorescence, laser flash photolysis, electron spin resonance (ESR), and steady state photolysis experiments. Molecular orbital calculations are also carried out. The overall excited state processes and the chemical mechanisms involved in the initiation step are detailed.

The objective of this work was to propose a novel low migration additive (i.e. a phosphine) to overcome the oxygen inhibition in a camphorquinone (CQ) base photoinitiating system for the polymerization of methacrylates (e.g. a bisphenol A‐glycidyl methacrylate (Bis‐GMA)/triethyleneglycol dimethacrylate (TEGDMA) blend (70%/30% w/w)) upon exposure to a commercial blue light emitting diode centred at 477 nm. CQ/amine/phosphine derivative or CQ/amine/iodonium salt/phosphine derivative combinations were studied. Real‐time Fourier transform IR and photo‐DSC experiments were used to monitor the polymerization profiles. Remarkably, it was found that the addition of the new phosphine derivative to CQ/amine or CQ/amine/iodonium salt noticeably improved the rate of polymerization and the final conversion in air. A low migration was found for this additive as shown by HPLC experiments in agreement with a copolymerizable behaviour. No additional yellowing of the film was observed. Electron spin resonance spectrometry was used to detect the produced radicals. The overall chemical mechanisms are investigated and discussed. © 2016 Society of Chemical Industry

This work describes the use of spatially acoustic techniques to identify the condition of electrodes in a commercial lithium-ion battery.