Frontiers in Chemistry (Jul 2021)

Supercritical CO2 Synthesis of Freestanding Se1-xSx Foamy Cathodes for High-Performance Li-Se1-xSx Battery

  • Chengwei Lu,
  • Ruyi Fang,
  • Kun Wang,
  • Zhen Xiao,
  • G. Gnana kumar,
  • Yongping Gan,
  • Xinping He,
  • Hui Huang,
  • Wenkui Zhang,
  • Yang Xia

DOI
https://doi.org/10.3389/fchem.2021.738977
Journal volume & issue
Vol. 9

Abstract

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Selenium-sulfur solid solutions (Se1-xSx) are considered to be a new class of promising cathodic materials for high-performance rechargeable lithium batteries owing to their superior electric conductivity than S and higher theoretical specific capacity than Se. In this work, high-performance Li-Se1-xSx batteries employed freestanding cathodes by encapsulating Se1-xSx in a N-doped carbon framework with three-dimensional (3D) interconnected porous structure (NC@SWCNTs) are proposed. Se1-xSx is uniformly dispersed in 3D porous carbon matrix with the assistance of supercritical CO2 (SC-CO2) technique. Impressively, NC@SWCNTs host not only provides spatial confinement for Se1-xSx and efficient physical/chemical adsorption of intermediates, but also offers a highly conductive framework to facilitate ion/electron transport. More importantly, the Se/S ratio of Se1-xSx plays an important role on the electrochemical performance of Li- Se1-xSx batteries. Benefiting from the rationally designed structure and chemical composition, NC@[email protected] cathode exhibits excellent cyclic stability (632 mA h g−1 at 200 cycle at 0.2 A g−1) and superior rate capability (415 mA h g−1 at 2.0 A g−1) in carbonate-based electrolyte. This novel NC@[email protected] cathode not only introduces a new strategy to design high-performance cathodes, but also provides a new approach to fabricate freestanding cathodes towards practical applications of high-energy-density rechargeable batteries.

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