Design and synthesis of C@MoSe2@NMWCNT heterostructure as anode material for Na+ batteries via Mo-based organic complexes

Abstract

Theoretically, molybdenum selenide (MoSe2) has the characteristic of high storage capacity for sodium ions, but it shows poor rate performance and cycle stability in actual sodium storage experiments. Additionally, heteroatom doping is beneficial to the high electronic performance of carbon materials. For example, the addition of nitrogen (N) to carbon nanotubes (CNT) leads to additional electrons on the surface of CNT, thus enhancing CNT conductivity. Herein, employing N-doped multi-wall CNT (NMWCNT), we synthesized C@MoSe2@NMWCNT nanocomposites that are endowed with heterojunctions. The results of DFT calculation suggest that the electron transfer intensity between the interfaces of C@MoSe2@NSWCNT (SW stands for single-wall) is obviously higher than that of C@MoSe2@SWCNT, and NSWCNT plays a role in promoting the electron transfer. In addition, the combination of MoSe2 with SWCNT can effectively reduce the Na+ diffusion energy barrier between MoSe2 layers in the C@MoSe2@NSWCNT composite (lowered from 0.91 to 0.69 eV), hence promoting Na+ mobility, and thus improving the performance of the system for Na+ storage. Experimentally, the PEG-200-2-C@MoSe2@NMWCNT system exhibited capacity of 226 mA h g−1 after 1100 cycles and 168 mA h 01 after 3600 cycles at a current density of 2 A g−1. Under the synergistic effect of carbon coating and NMW`CNT network, the stability of the Na+ storage of MoSe2 is significantly improved. This work can shed light for the research of nitrogen doped carbon-based materials.