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To enhance the utilization of sulfur in lithium−sulfur batteries, threedimensional tungsten nitride (WN) mesoporous foam blocks are designed to spatially localize the soluble Li 2 S 6 and Li 2 S 4 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 (Li 2 S 8 > Li 2 S 6 > Li 2 S 4 ), while the interactions between WN and the insoluble Li 2 S 2 /Li 2 S 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 reversible capacity of 358 mAh g −1 is maintained with a high Coulombic efficiency approaching to 100%, even after 500 cycles at 2C. As guided by in silico design, this work not only provides an effective strategy to improve the retentivity of polysulfides but also underpins that properly architectured WN can be effective retainers of polysulfides.

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Mg2FeH6 hydride has been viewed as a high-density and efficient material for thermal energy storage systems. However, the synthesis of the pure hydride is still a big problem for its application. This work combines experiment and density functional theory calculations to explore the conditions under which the synthesis is thermodynamically optimal. The experimental results show that Mg2FeH6 can be successfully synthesized by reactive ball milling within 5 h. The synthesis mechanism is revealed by numerical simulation to be indirect hydrogenation in two steps: one accelerating mode, in which MgH2 is probably formed with the reaction enthalpy of 75.57 kJ/mol H2, and then, a sluggish mode, in which the evolution of Mg2FeH6 happens via the reaction between MgH2 and Fe with the reaction enthalpy of 65.27 kJ/mol H2. In addition, the rehydrogenation of the mixture under low pressure and high temperature >400 °C results in a high degree of crystallinity of Mg2FeH6 and a maximum hydrogen capacity of 5.01 wt %.