Anchoring SnS2 on TiC/C Backbone to Promote Sodium Ion Storage by Phosphate Ion Doping.

Abstract

Tin disulfide (SnS2 ) shows promising properties toward sodium ion storage with high capacity, but its cycle life and high rate capability are still undermined as a result of poor reaction kinetics and unstable structure. In this work, phosphate ion (PO4 3- )-doped SnS2 (P-SnS2 ) nanoflake arrays on conductive TiC/C backbone are reported to form high-quality P-SnS2 @TiC/C arrays via a hydrothermal-chemical vapor deposition method. By virtue of the synergistic effect between PO4 3- doping and conductive network of TiC/C arrays, enhanced electronic conductivity and enlarged interlayer spacing are realized in the designed P-SnS2 @TiC/C arrays. Moreover, the introduced PO4 3- can result in favorable intercalation/deintercalation of Na+ and accelerate electrochemical reaction kinetics. Notably, lower bandgap and enhanced electronic conductivity owing to the introduction of PO4 3- are demonstrated by density function theory calculations and UV-visible absorption spectra. In view of these positive factors above, the P-SnS2 @TiC/C electrode delivers a high capacity of 1293.5 mAh g-1 at 0.1 A g-1 and exhibits good rate capability (476.7 mAh g-1 at 5 A g-1 ), much better than the SnS2 @TiC/C counterpart. This work may trigger new enthusiasm on construction of advanced metal sulfide electrodes for application in rechargeable alkali ion batteries.