Double‐Walled NiTeSe–NiSe₂ Nanotubes Anode for Stable and High‐Rate Sodium‐Ion Batteries

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–NiSe 2 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–NiSe 2 double‐walled nanotubes and underlying mechanism of the enhanced performance are revealed by in situ and ex situ transmission electron microscopy and theoretical calculations.