Engineering catalytic defects via molecular imprinting for high energy Li-S pouch cells

Heterogeneous catalysis promises to accelerate sulfur-involved conversion reactions in lithium-sulfur batteries. Solid-state Li₂S dissociation remains as the rate-limiting step because of the weakly matched solid-solid electrocatalysis interfaces. We propose an electrochemically molecular-imprinting strategy to have a metal sulfide (MS) catalyst with imprinted defects in positions from which the pre-implanted Li₂S has been electrochemically removed. Such tailor-made defects enable the catalyst to bind exclusively to Li atoms in Li₂S reactant and elongate the Li-S bond, thus decreasing the reaction energy barrier during charging. The imprinted Ni₃S₂ catalyst shows the best activity due to the highest defect concentration among the MS catalysts examined. The Li₂S oxidation potential is substantially reduced to 2.34 V from 2.96 V for the counterpart free of imprinted vacancies, and an Ah-level pouch cell is realized with excellent cycling performance. With a lean electrolyte/sulfur ratio of 1.80 μL mg_S ^-1, the cell achieves a benchmarkedly high energy density beyond 500 Wh kg^-1.