Construction of spontaneous built-in electric field on heterointerface furnishing continuous efficient adsorption-directional migration-conversion of polysulfides.

Abstract

Integrating sulfur with efficient electrocatalysts remains a pressing need in lithium-sulfur (Li-S) batteries for modulating the sluggish conversion kinetics and restricting the shuttle behavior of lithium polysulfides (LiPSs). Herein, a compact p-type Fe₃O₄ and n-type MoS₂ heterostructure embedded on nitrogen-doped porous carbon (Fe₃O₄-MoS₂-NPC-0.5) is meticulously constructed as dual-functional hosts that can facilitate continuous catalytic conversion of LiPSs. The p-type Fe₃O₄ exhibits a high affinity for polysulfides, while n-type MoS₂ enables effective catalysis of LiPSs. The successful migration of LiPSs from Fe₃O₄ to MoS₂ is bridged due to a spontaneous built-in electric field (BIEF) at the p-n heterojunction interface. The synergistic effect prevents the passivation of adsorption sites on Fe₃O₄ and enhances the efficient catalytic conversion capabilities of MoS₂. Consequently, the battery with Fe₃O₄-MoS₂-NPC-0.5/S exhibits a prominent initial capacity of 1120.6 mAh g^-1 at 2 C, maintains outstanding cyclability with a capacity attenuation rate of 0.045 % per cycle at 0.5 C, and high sulfur utilization at large sulfur loadings. This work offers insights into optimizing the performance-enhanced Li-S battery electrodes by the formation of a dynamic "trapping-directional migration-conversion" reaction.