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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.
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Chemistry‐Performance Relationships of Polymer Gel‐Electrolytes for Mg−S and Li−S Batteries: Influence of Network Cation Solvation Capacity on Polymer‐Polysulfide Interactions
Abstract Metal‐sulfur batteries are a promising next‐generation energy storage technology, offering high theoretical energy densities with low cost and good sustainability. An active area of research is the development of electrolytes that address unwanted migration of sulfur and intermediate species known as polysulfides during operation of metal‐sulfur batteries, a phenomenon that leads to low energy efficiency and short life‐spans. A particular class of electrolytes, gel polymer electrolytes, are especially attractive for their ability to repel polysulfides on the basis of structure, electrostatics, and other polymer properties. Herein, within the context of magnesium‐ and lithium‐sulfur batteries, we investigate the impact of gel polymer electrolyte cation solvation capacity, a property related to network dielectric constant and chemistry, on sulfur/polysulfide‐polymer interactions, an understudied property‐performance relationship. Polymers with lower cation solvation capacity are found to permanently absorb less polysulfide active material, which increases sulfur utilization for Li−S batteries and significantly increases charge efficiency and life‐span for Li−S and Mg−S batteries.
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- Award ID(s):
- 1706370
- PAR ID:
- 10369052
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhysChem
- Volume:
- 23
- Issue:
- 7
- ISSN:
- 1439-4235
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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