NiSe2 Nanooctahedra as an Anode Material for High-Rate and Long-Life Sodium-Ion Battery.

In this article, we report NiSe2 nanooctahedra as a promising anode material for sodium-ion batteries (SIBs). They exhibit outstanding long-term cyclic stability (313 mAh/g after 4000 cycles at 5 A/g) and excellent high-rate capability (175 mAh/g at 20 A/g). Besides, the initial Coulombic efficiency of NiSe2 is also very impressive (over 90%). Such remarkable performances are attributed to good conductivity, structural stability, and the pseudocapacitive behavior of the NiSe2. Furthermore, the sodium ion storage mechanism of NiSe2 is first investigated by in situ XRD and ex situ XRD. These highlights give NiSe2 a competitive strength for rechargeable SIBs.