Sodium storage and transport properties in pyrolysis synthesized MoSe2 nanoplates for high performance sodium-ion batteries

The development of novel sodium-ion batteries has been hindered by the lack of ideal anode materials. Herein, we report both experimental and theoretical assessment of layered MoSe2 nanoplates as the anode materials. The MoSe2 nanoplates are successfully synthesized by a facile thermal-decomposition process. As the anode, the MoSe2 nanoplates are capable of delivering the initial discharge and charge capacities of 513 and 440 mAh g(-1) at the current of 0.1C in a voltage of 0.1-3 V, respectively. The analysis of Ex-situ XRD patterns reveals that there is no slippage between layers and the change of coordination of molybdenum when the MoSe2 electrode is discharged to 0.6 V and conversion reactions during the following discharge/charge process are also demonstrated. In addition, the electronic structure, Na ions transport and conductivity are investigated by first-principles calculation. A quasi-2D energy favorable trajectory is proposed to illustrate the sodium ion vacancy-hopping migration mechanism form octahedron to tetrahedron in MoSe2 lattice. The results suggest great potential of MoSe2 as an anode material for Na ion batteries. (C) 2015 Elsevier B.V. All rights reserved.