Polysulfide Adsorption by Iron Oxide and Chromium Oxide: Effects on Cycle Life and Redox Kinetics of Lithium‐Sulfur Cells

Small amounts of iron(III) oxide and chromium(III) oxide improve the cycling stability of lithium-sulfur batteries: Adsorption isotherms were used to investigate the adsorption behavior of polysulfides on the oxides. Based on these results, the improvement in cycling stability is explained by the reduction of the polysulfide shuttle-mechanism. Additionally, the cyclic voltammograms showed a catalytic effect of the oxides on the cell reaction.

Abstract

Lithium-sulfur batteries have the potential to replace lithium-ion batteries in the future due to their high theoretical capacity and energy density but suffer from low cycling stability caused by the polysulfide shuttle. This work demonstrates a reduction of the polysulfide shuttle and increased cycling stability by using iron oxide and chromium oxide as additives for a simply fabricated lithium sulfide cathode. Adsorption isotherms were recorded, and monolayer adsorption capacities were determined for a better understanding of the interactions between transition metal oxides and polysulfides. A significant reduction of the shuttle mechanism can be deduced from the cyclization experiments. Similarly, the catalytic influence of chromium oxide and iron oxide on the oxidation could be shown by cyclic voltammetry.

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