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Abstract Despite large theoretical energy densities, metal‐sulfide electrodes for energy storage systems face several limitations that impact the practical realization. Here, we present the solution‐processable, room temperature (RT) synthesis, local structures, and application of a sulfur‐rich Mo3S13chalcogel as a conversion‐based electrode for lithium‐sulfide batteries (LiSBs). The structure of the amorphous Mo3S13chalcogel is derived throughoperandoRaman spectroscopy, synchrotron X‐ray pair distribution function (PDF), X‐ray absorption near edge structure (XANES), and extended X‐ray absorption fine structure (EXAFS) analysis, along with ab initio molecular dynamics (AIMD) simulations. A key feature of the three‐dimensional (3D) network is the connection of Mo3S13units through S−S bonds. Li/Mo3S13half‐cells deliver initial capacity of 1013 mAh g−1during the first discharge. After the activation cycles, the capacity stabilizes and maintains 312 mAh g−1at a C/3 rate after 140 cycles, demonstrating sustained performance over subsequent cycling. Such high‐capacity and stability are attributed to the high density of (poly)sulfide bonds and the stable Mo−S coordination in Mo3S13chalcogel. These findings showcase the potential of Mo3S13chalcogels as metal‐sulfide electrode materials for LiSBs.
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Molybdenum Carbide Electrocatalyst In Situ Embedded in Porous Nitrogen‐Rich Carbon Nanotubes Promotes Rapid Kinetics in Sodium‐Metal–Sulfur Batteries
Abstract This is the first report of molybdenum carbide‐based electrocatalyst for sulfur‐based sodium‐metal batteries. MoC/Mo2C is in situ grown on nitrogen‐doped carbon nanotubes in parallel with formation of extensive nanoporosity. Sulfur impregnation (50 wt% S) results in unique triphasic architecture termed molybdenum carbide–porous carbon nanotubes host (MoC/Mo2C@PCNT–S). Quasi‐solid‐state phase transformation to Na2S is promoted in carbonate electrolyte, with in situ time‐resolved Raman, X‐ray photoelectron spectroscopy, and optical analyses demonstrating minimal soluble polysulfides. MoC/Mo2C@PCNT–S cathodes deliver among the most promising rate performance characteristics in the literature, achieving 987 mAh g−1at 1 A g−1, 818 mAh g−1at 3 A g−1, and 621 mAh g−1at 5 A g−1. The cells deliver superior cycling stability, retaining 650 mAh g−1after 1000 cycles at 1.5 A g−1, corresponding to 0.028% capacity decay per cycle. High mass loading cathodes (64 wt% S, 12.7 mg cm−2) also show cycling stability. Density functional theory demonstrates that formation energy of Na2Sx(1 ≤x ≤ 4) on surface of MoC/Mo2C is significantly lowered compared to analogous redox in liquid. Strong binding of Na2Sx(1 ≤x ≤ 4) on MoC/Mo2C surfaces results from charge transfer between the sulfur and Mo sites on carbides’ surface.
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- Award ID(s):
- 1938833
- PAR ID:
- 10445238
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 34
- Issue:
- 26
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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