Nano-necklace Co/β-Mo2C hetero-nanodots encapsulating into carbon nanotubes with strong adsorption and catalytic conversion of polysulfides for lithium‑sulfur batteries separator

Abstract

Due to their high theoretical capacity and high energy density, Lithium‑sulfur (LiS) batteries become the research hotspot in the field of electrochemical energy storage. However, the serious capacity loss caused by the shuttle effect and the decomposition of polysulfides is the biggest obstacle in the research process and practical application of lithium‑sulfur batteries. Herein, cobalt (Co) and molybdenum carbide (Mo2C) hetero-nanodots wrapping into nitrogen-doped carbon nanotubes (Co-Mo2C@NCNTs) are successfully prepared by direct self-catalysis annealing process. When utilized into the polypropylene (PP) separator modifier, the batteries assembled with Co-Mo2C@NCNTs//PP separator presents high capacity and outstanding rate capability. Specifically, it's worth noting that the cells display a high initial specific capacity of 1463.6mAh g−1 at 0.1C, superior rate capacity of 778.7 mAh g−1 at 3C, and excellent cycle stability with capacity decay rate of only 0.11 % per cycle for 500 cycles at 0.5C. Besides, the outstanding electrochemical performance is also demonstrated under high sulfur loading (3.5 mg cm−2). This work provides a novel guidance direction for high-performance lithium‑sulfur batteries from separator modification.