Double-Walled NiTeSe-NiSe2 Nanotubes Anode for Stable and High-Rate Sodium-Ion Batteries.

ABSTRACT

Electrodes made of composites with heterogeneous structure hold great potential for boosting ionic and charge transfer and accelerating electrochemical reaction kinetics. Herein, hierarchical and porous double-walled NiTeSe-NiSe2 nanotubes are synthesized by a hydrothermal process assisted in situ selenization. Impressively, the nanotubes have abundant pores and multiple active sites, which shorten the ion diffusion length, decrease Na+ diffusion barriers, and increase the capacitance contribution ratio of the material at a high rate. Consequently, the anode shows a satisfactory initial capacity (582.5 mA h g-1 at 0.5 A g-1 ), a high-rate capability, and long cycling stability (1400 cycles, 398.6 mAh g-1 at 10 A g-1 , 90.5% capacity retention). Moreover, the sodiation process of NiTeSe-NiSe2 double-walled nanotubes and underlying mechanism of the enhanced performance are revealed by in situ and ex situ transmission electron microscopy and theoretical calculations.