To DISP or Not? The Far-Reaching Reaction Mechanisms Underpinning Lithium-Air Batteries.

The short history of research on Li-O batteries has seen a remarkable number of mechanistic U-turns over the years. From the initial use of carbonate electrolytes, that were then found to be entirely unsuitable, to the belief that (su)peroxide was solely responsible for degradation, before the more reactive singlet oxygen was found to form, to the hypothesis that capacity depends on a competing surface/solution mechanism before a practically exclusive solution mechanism was identified. Herein, we argue for an ever-fresh look at the reported data without bias towards supposedly established explanations.

Singlet oxygen formation in non-aqueous oxygen redox chemistry: direct spectroscopic evidence for formation pathways and reliability of chemical probes.

Singlet oxygen (O) formation is now recognised as a key aspect of non-aqueous oxygen redox chemistry. For identifying O, chemical trapping 9,10-dimethylanthracene (DMA) to form the endoperoxide (DMA-O) has become the main method due to its sensitivity, selectivity, and ease of use. While DMA has been shown to be selective for O, rather than forming DMA-O with a wide variety of potentially reactive O-containing species, false positives might hypothetically be obtained in the presence of previously overlooked species.

Exclusive Solution Discharge in Li-O Batteries?

Capacity, rate performance, and cycle life of aprotic Li-O batteries critically depend on reversible electrodeposition of LiO. Current understanding states surface-adsorbed versus solvated LiO controls LiO growth as surface film or as large particles. Herein, we show that LiO forms across a wide range of electrolytes, carbons, and current densities as particles via solution-mediated LiO disproportionation, bringing into question the prevalence of any surface growth under practical conditions.

Nickel-Doped Silver Sulfide: An Efficient Air-Stable Electrocatalyst for Hydrogen Evolution from Neutral Water.

A low-cost, platinum-free electrocatalyst for hydrogen (H) generation via the water splitting reaction holds great promise to meet the demand of clean and sustainable energy sources. Recent studies are mainly concerned with semiconducting materials like sulfides, selenides, and phosphides of different transition metals as electrocatalysts. Doping of the transition metals within the host matrix is a good strategy to improve the electrocatalytic activity of the host material.