Probing the effect of Se doping in S cathode for high performance Mg-S batteries

•Se doping strengthens Mg-S bond, improving Mg/Mg2+ redox reactions.•Operando Raman spectroscopy and ex-situ XPS reveals the redox mechanism.•Investigated the composition of the anode SEI at different depths.•TA layered MoS2-functionalized separator was first introduced in Mg-S batteries. Magnesium-...

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Veröffentlicht in:Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-11, Vol.499, p.156682, Article 156682
Hauptverfasser: Yao, Yingying, Li, Yinghui, Zhan, Yang, Li, Zhao, Li, Zi, Laine, Richard M., Zou, Jianxin
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Sprache:eng
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Zusammenfassung:•Se doping strengthens Mg-S bond, improving Mg/Mg2+ redox reactions.•Operando Raman spectroscopy and ex-situ XPS reveals the redox mechanism.•Investigated the composition of the anode SEI at different depths.•TA layered MoS2-functionalized separator was first introduced in Mg-S batteries. Magnesium-sulfur (Mg-S) batteries present an attractive option as a new type of energy storage device given their high energy density, safety and the use of low-cost original materials. However, magnesium polysulfide (MgPS) is susceptible to dissolution and shuttling, and the insulating nature of sulfur and MgS leads to high overpotentials and low columbic efficiencies. The selenium-sulfur system is noted to offer enhanced electronic conductivity and improved sulfur utilization. In this study, S K-edge X-ray absorption near-edge structure (XANES) spectra demonstrate that Se doping mitigates irreversibility in Mg-S batteries. Mg-K spectra demonstrate that Se dopants induce local negative charges on S, strengthening the Mg-S bond compared to that of pure sulfur, thereby promoting Mg/Mg2+ redox reactions. Operando Raman spectroscopy was also used to reveal Mg-S0.9Se0.1/C battery redox mechanisms. Hence, kinetically favored S0.9Se0.1/C cathodes deliver an initial capacity of ∼1350 mAh·g−1 at 0.2C. Furthermore, separators modified with layered MoS2 entrap polysulfides, thereby postponing cell death. Thus, Mg-S battery with a S0.9Se0.1/C cathode and a MoS2@polypropylene (PP) separator exhibit a reversible capacity of ∼200 mAh·g−1 at 0.2C after 250 cycles, with a low fade rate of 4 mAh·g−1/cycle. This study delineates the overall impact of Se doped cathodes on Mg-S batteries. Moreover, the MoS2 modified separator provides a route to chemically immobilize MgPS and accelerate sulfur redox reactions, consequently enabling high capacities and sustained cycling.
ISSN:1385-8947
DOI:10.1016/j.cej.2024.156682