Sulfurized polyacrylonitrile is suggested to contain S n ( n ≤ 4) and shows good electrochemical performance in carbonate electrolytes for lithium sulfur batteries. However inferior results in ether electrolytes suggest that high solubility of Li 2 S n ( n ≤ 4) trumps the limited redox conversion, leading to dissolution and shuttling. Here, we introduce a small amount of selenium in sulfurized polyacrylonitrile to accelerate the redox conversion, delivering excellent performance in both carbonate and ether electrolytes, including high reversible capacity (1300 mA h g −1 at 0.2 A g −1 ), 84% active material utilization and high rate (capacity up to 900 mA h g −1 at 10 A g −1 ). These cathodes can undergo 800 cycles with nearly 100% Coulombic efficiency and ultralow 0.029% capacity decay per cycle. Polysulfide dissolution is successfully suppressed by enhanced reaction kinetics. This work demonstrates an ether compatible sulfur cathode involving intermediate Li 2 S n ( n ≤ 4), attractive rate and cycling performance, and a promising solution towards applicable lithium-sulfur batteries.

This work explores the interactions of cations with highly negatively charged solid/aqueous interfaces. Vibrational sum frequency spectroscopy (VSFS) was exploited to observe interfacial water structure on the surfaces of fused quartz and titanium dioxide (TiO 2 ) in the presence of nine chloride salts with different alkali, alkaline earth, and transition metal cations. The results showed prominent specific cation effects at low concentration. The cations followed a direct Hofmeister series. On quartz surfaces the series was:

Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10(-3) S cm(-1) at room temperature, among the highest reported values to date. In this work, we investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using ab initio density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.