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Designing Effective Solvent–Catalyst Interface for Catalytic Sulfur Conversion in Lithium–Sulfur Batteries
journal contribution
posted on 2019-12-12, 18:03 authored by Zhejun Li, Haoran Jiang, Nien-Chu Lai, Tianshou Zhao, Yi-Chun LuSulfur-based redox materials are promising next-generation
energy
storage solutions. Identifying electrode and electrolyte properties
that facilitate polysulfide reduction reactions is critical for rational
material designs for sulfur-based batteries. In this study, we reveal
that the effectiveness of the polysulfide reduction is governed by
the resolved binding strength of polysulfide on the electrode surface,
which is dictated by the competition between electrode’s polysulfide
chemisorption strength and solvent’s polysulfide solvation
strength. Using titanium-based model compounds (TiX) as examples,
we show that the polysulfide reduction kinetics and sulfur utilization
increase with increasing polysulfide chemisorption strength of TiX,
which can be associated with the decreasing electronegativity of nonmetal
element (X). Strong coordinating solvent reduces catalyst’s
efficacy by reducing the binding strength between polysulfide and
the catalysts, highlighting that a weak solvent coordination is a
critical selection criterion for effective catalysis in Li–S
batteries. Our study reveals physical origins controlling the catalytic
processes of polysulfide reduction reactions and unravels the interplay
of solvent–polysulfide–catalyst competition for achieving
higher-energy and reversible sulfur-based energy storage.