Improved Redox Reaction of Lithium Polysulfides on the Interfacial Boundary of Polar CoC2O4 as a Polysulfide Catenator for a High-Capacity Lithium-Sulfur Battery

Abstract

The performance of cobalt oxalate as an electrocatalyst in a lithium-sulfur battery (LSB) is improved owing to the suitable adsorbent properties of sulfur. The adsorption mechanism is elucidated by UV/Vis spectroscopy and surface analysis through X-ray photoelectron spectroscopy. Li2S6 is converted into thiosulfate and polythionate by a catenation reaction on the interfacial boundary of CoC2O4 contacted with carbon. Following this, the active polythionate and short-chained liquid lithium polysulfides (LiPS) bound to the cobalt surface are further reduced as CoC2O4 reduces the overpotential to facilitate the LiPS redox reaction, leading to high specific capacity, lower self-discharge rate, and stable long-term cycling performance.