Abstract The development of practical lithium–sulfur (Li–S) batteries with prolonged cycle life and high Coulombic efficiency is limited by both parasitic reactions from dissolved polysulfides and mossy lithium deposition. To address these challenges, here lithium trithiocarbonate (Li2CS3)-coated lithium sulfide (Li2S) is employed as a dual-function cathode material to improve the cycling performance of Li–S batteries. Interestingly, at the cathode, Li2CS3 forms an oligomer-structured layer on the surface to suppress polysulfide shuttle. The presence of Li2CS3 alters the conventional sulfur reaction pathway, which is supported by material characterization and density functional theory calculation. At the anode, a stable in situ solid electrolyte interphase layer with a lower Li-ion diffusion barrier is formed on the Li-metal surface to engender enhanced lithium plating/stripping performance upon cycling. Consequently, the obtained anode-free full cells with Li2CS3 exhibit a superior capacity retention of 51% over 125 cycles, whereas conventional Li2S cells retain only 26%. This study demonstrates that Li2CS3 inclusion is an efficient strategy for designing high-energy-density Li–S batteries with extended cycle life.
Implications of in situ chalcogen substitutions in polysulfides for rechargeable batteries
The electrochemical behavior of sulfur-based batteries is intrinsically governed by polysulfide species. Here, we compare the substitutions of selenium and tellurium into polysulfide chains and demonstrate their beneficial impact on the chemistry of lithium–sulfur batteries. While selenium-substituted polysulfides enhance cathode utilization by effectively catalyzing the sulfur/Li 2 S conversion reactions due to the preferential formation of radical intermediates, tellurium-substituted polysulfides improve lithium cycling efficiency by reducing into a passivating interfacial layer on the lithium surface with low Li + -ion diffusion barriers. This unconventional strategy based on “molecular engineering” of polysulfides and exploiting the intrinsic polysulfide shuttle effect is validated by a ten-fold improvement in the cycle life of lean-electrolyte “anode-free” pouch cells. Assembled with no free lithium metal at the anode, the anode-free configuration maximizes the energy density, mitigates the challenges of handling thin lithium foils, and eliminates self-discharge upon cell assembly. The insights generated into the differences between selenium and tellurium chemistries can be applied to benefit a broad range of metal–chalcogen batteries as well as chalcogenide solid electrolytes.
- Award ID(s):
- 2011415
- Publication Date:
- NSF-PAR ID:
- 10331093
- Journal Name:
- Energy & Environmental Science
- Volume:
- 14
- Issue:
- 10
- Page Range or eLocation-ID:
- 5423 to 5432
- ISSN:
- 1754-5692
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1039/D1EE01113H
