Co9S8 nanorods as electrocatalyst to enhance polysulfides conversion and alleviate passivation in Li-S batteries under lean electrolyte conditions.

Due to the high theoretical energy density of lithium-sulfur (Li-S) batteries, they have been accepted as the next-generation energy storage system. Nevertheless, the current performance Li-S batteries is still unsatisfactory under lean electrolyte conditions. It is because of sluggish deposition of Li2S2/Li2S passivating sulfur/electrolyte interface, thus leading to lower sulfur use and bad rate performances of Li-S batteries. Herein, a novel Co9S8 nanorods based catalytic interlayer placed between cathode and separator is proposed. The interlayer possesses a three-dimensional open structure, which facilitates electrolyte infiltration, but without trapping too much electrolyte. As a result, the electrocatalytic Co9S8 nanorods within the interlayer promote faster electrochemical kinetics and enhance the conversion of polysulfides, thus results in the higher specific discharge capacity, better rate and cycling performance. This work proves a feasible method in developing practical Li-S batteries.