Abstract
The lithium-sulfur battery (LSB) is a potential candidate for next-generation energy stor age devices. However, LSBs have several problems: (1) poor electronic conductivities; (2) dissolution and diffusion of lithium polysulfides into the electrolyte; (3) drastic volume changes of sulfur during electrochemical processes; and (4) sluggish reaction kinetics of insulating Li2S during cycling. To solve these challenges, we propose the spherical tem plating of MXene sheets decorated with CoSe2 nanoparticles on sulfur nanospheres. In recent years, there has been an increase in studies on incorporating MXenes and transi tion metal catalysts into LSBs. As a polar 2D material, MXene is known to have excellent electrical conductivity and strong chemisorption ability towards LiPSs. However, MXene layers are prone to restacking or aggregation, limiting ionic transport through the elec trode and hindering the electrochemical performance. Hence, there have been attempts to integrate MXenes into 3D macroporous structures through spherical templating. Tran sition metal catalysts are also increasingly incorporated into the sulfur hosts of LSBs due to their strong dipole-dipole interactions and chemisorption abilities towards lithium polysulfides, producing exceptional results in LSBs.Inspired by previous works, polymorphic CoSe2 nanoparticles containing both cubic phases and orthorhombic phases were grown on MXene nanosheets. These nanoparticle decorated-MXene sheets were templated by sulfur nanospheres before being incorporated into LSBs. In general, we observe that these nanoparticle decorated-MXene spheres have better electrochemical performances than conventionally MXene-templated sulfur nanospheres despite restricted lithium-ion diffusion rates at high currents