Trace amounts of MoB MBene with layered configuration trigger catalytic converter of polysulfide

Abstract

The formation of soluble lithium polysulfide severely limits the performance of the reversible capacity and cycle stability in lithium‑sulfur batteries. Herein, a carbon fiber cathode of LiS battery is proposed, and the two-dimensional metal boride material MoB MBene is selected as the catalyst of lithium‑sulfur battery. Theoretical calculations and experimental data have confirmed that MoB MBene performs exceptionally well in adsorbing polysulfides and preventing the shuttle effect. It also expedites the solid-liquid-solid phase transition and efficiently decrease the Li2S breakdown energy barrier. MoB MBene not only anchors polysulfides by generating MoS bonds in LiS redox reaction, but also accelerates the kinetics of polysulfide conversion by lowering the energy barrier of polysulfides conversion. By adopting MoB MBene as a catalyst, a lithium‑sulfur battery achieved a long cycle life (with only 0.0779 % attenuation after 800 cycles at 1C) and a high initial discharge capacity (1105 mAh g−1). This work could provide new perspectives on using MBene as a catalyst for LiS chemistry.