Selective sulfur conversion with surface engineering of electrocatalysts in a lithium–sulfur battery

Abstract The sluggish kinetics of multiphase sulfur conversion with homogeneous and heterogeneous electrochemical processes, causing the “shuttle effect” of soluble polysulfide species (PSs), is the challenges in terms of lithium–sulfur batteries (LSBs). In this paper, a Mn₃O_4−x catalyst, which has much higher activity for heterogeneous reactions than for homogeneous reactions (namely, preferential‐activity catalysts), is designed by surface engineering with rational oxygen vacancies. Due to the rational design of the electronic structure, the Mn₃O_4−x catalyst prefers to accelerate the conversion of Li₂S₄ into Li₂S₂/Li₂S and optimize Li₂S deposition, reducing the accumulation of PSs and thus suppressing the “shuttle effect.” Both density functional theory calculations and in situ X‐ray diffraction measurements are used to probe the catalytic mechanism and identify the reaction intermediates of MnS and Li_yMn_zO_4−x for fundamental understanding. The cell with Mn₃O_4−x delivers an ultralow attenuation rate of 0.028% per cycle over 2000 cycles at 2.5 C. Even with sulfur loadings of 4.93 and 7.10 mg cm⁻² in a lean electrolyte (8.4 µL mg s⁻¹), the cell still shows an initial areal capacity of 7.3 mAh cm⁻². This study may provide a new way to develop preferential‐activity heterogeneous‐reaction catalysts to suppress the “shuttle effect” of the soluble PSs generated during the redox process of LSBs.