Built-In Electric Field on the Mott-Schottky Heterointerface-Enabled Fast Kinetics Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur (Li-S) batteries (LSBs) have been considered one of the most potential candidates to substitute traditional Li-ion batteries (LIBs), owing to their high theoretical energy density and low cost. Nevertheless, the shuttle effect and the sluggish redox kinetics of lithium polysulfides (LiPSs) have long been obstacles to realizing stable LSBs with high reversible capacity. In this study, we proposed a metal-semiconductor (Mo and MoO2) heterostructure with the hollow microsphere morphology as an effective Mott-Schottky electrocatalyst to boost sulfur electrochemistry. The hollow structure can physically inhibit the shuttling of LiPSs and accommodate the volume fluctuation during cycling. More importantly, the built-in electric field at the heterointerfacial sites can effectively accelerate the reduction of LiPSs and oxidation of Li2S, thereby reaching a high sulfur utilization. With the assistance of the Mo/MoO2 catalyst, the cell exhibited prominent rate capability and stable long-term cycling performance, showing a high capacity of 630 mA h·g-1 at 4 C and a low decay of 0.073% at 1 C after 500 cycles. Even with high areal sulfur loading of 10.0 mg·cm-2, high capacity and good cycle stability were achieved at 0.2 C under lean electrolyte conditions (E/S ratio of 6 μL·mg-1).