S-doped C@MoSe2(1-x)S2x@MWCNT heterostructure as high-rate and long-cycle stability anodes for Na+ batteries

Abstract

Herein, we successfully synthesized C@MoSe2(1-x)S2x@MWCNT nanocomposite with heterojunctions as long-term stability anodes for sodium ion batteries (SIB). According to DFT calculations, the barrier of Na+ migration between MoSe2(1-x)S2x interlayers and that between GR@MoSe2(1-x)S2x@SWWCNT interlayers is 0.48 eV and 0.45 eV, respectively, significantly lower than that between MoSe2 interlayers (0.91 eV). Therefore, the introduction of S can enhance Na+ transport. The Se element can provide a larger interlayer spacing of MoSe2(1−x)S2x than MoS2, and MWCNT with high conductivity and thermal stability can be used as effective carriers for charge transfer. As an electrode material, PEG-200-2-C@MoSe2(1-x)S2x@MWCNT showed good performance for SIB: 300 mA h g-1 (500 cycles), 256 mA h g-1 (1000 cycles), 165 mA h g-1 (3000 cycles) and 126 mA h g-1 (6000 cycles) under the current density of 10 A g-1.