Improved redox reaction of lithium polysulfides on the interfacial boundary of polar CoC2O4 as a polysulfide catenator for a high-capacity lithium-sulfur battery.

Herein, we report the outstanding performance of cobalt oxalate as an electrocatalyst in a lithium-sulfur battery (LSB) owing to the suitable adsorbent properties of sulfur. By UV-vis and surface analysis through X-ray photoelectron spectroscopy, the adsorption mechanism was elucidated. Li 2 S 6 is converted to thiosulfate and polythionate by a catenation reaction on the interfacial boundary of CoC 2 O 4 contacted with carbon. Following this, the active polythionate and short-chained liquid lithium polysulfides (LiPS) bound to the cobalt surface were further reduced as CoC 2 O 4 reduces the overvoltage to facilitate the LiPS redox reaction, leading to high specific capacity, lower self-discharge rate, and stable long-term cycle performance.