Sulfur in Mesoporous Tungsten Nitride Foam Blocks: a Rational Lithium Polysufides Confinement Experimental Design Strategy Augmented by Theoretical Predictions

To enhance the utilization of sulfur in lithium–sulfur batteries, three-dimensional tungsten nitride (WN) mesoporous foam blocks are designed to spatially localize the soluble Li2S6 and Li2S4 within the pore spaces. Meanwhile, the chemisorption behaviors of polysulfides and the capability of WN as an effective confiner are systematically investigated through density functional theory calculations and experimental studies. The theoretical calculations reveal a decrease in chemisorption strength between WN and the soluble polysulfides (Li2S8 > Li2S6 > Li2S4), while the interactions between WN and the insoluble Li2S2/Li2S show a high chemisorption strength of ca. 3 eV. Validating theoretical insights through electrochemical measurements further manifest that the assembled battery configurations with sulfur cathode confined in the thickest WN blocks exhibit the best rate capabilities (1090 and 510 mAh g–1 at 0.5C and 5C, respectively) with the highest initial Coulombic efficiency of 90.5%. Moreover, a reversi...