0D-2D multifunctional bimetallic MOF derivative-MXene heterojunction for high areal capacity lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries have attracted much attention due to their high specific capacity. However, at high loads and rates, the polysulfides conversion rate and ion transport of batteries are slow, limiting their commercialization. This work reports zero-dimensional (0D) bimetallic MOF derivatives grown in situ on two-dimensional (2D) MXene by electrostatic adsorption (FeCo@TiC). The 0D bimetallic structure effectively avoids the stacking of MXene while providing a dual catalytic site for polysulfides. The 2D structure of MXene also provides a large number of pathways for the rapid diffusion of lithium ions. This 0D-2D heterostructured heterogeneous catalyst with bimetallic synergistic active sites efficiently immobilizes and catalyzes polysulfides, providing a fast charge transfer pathway for the electrochemical reaction of lithium polysulfides. The Li-S battery with this multifunctional 0D-2D heterojunction structure catalyst has outstanding high rate capacity (703 mAh g at 4 C at room temperature and 555 mAh g at 2 C at 0 °C), fascinating capacity at high load (5.5 mAh cm after 100 cycles at a high sulfur content of 8.2 mg cm). The study provides new ideas for the commercialization of high-efficiency Li-S batteries.