Semimetallic 1T′ WTe2 Nanorods as Anode Material for the Sodium Ion Battery

Highly crystalline semimetallic 1T′ WTe2 nanorods (WTe2 NRs) and WTe2 nanoflowers (WTe2 NFs) are applied as anode materials for the sodium ion battery (SIB) for the first time. WTe2 NRs and NFs are synthesized through a novel two-step process with hydrothermal-derived WO3 transformed into WTe2 NRs and NFs after a chemical vapor deposition process. The performance of the WTe2 SIB anode is highly influenced by WTe2 morphology. WTe2 NRs have shown high capacity in sodium ion storage, with an excellent rate and cycling stability. The initial discharge capacity for WTe2 NRs is 442 mA h g–1 at the current density of 0.1 A g–1 and remains at 221 mA h g–1 after 100 cycles, while WTe2 NFs show 324 mA h g–1 initial capacity and remain at 260 mA h g–1 after 40 cycles. The Coulombic efficiencies of both WTe2 NR and NF anodes are as high as 98.83 and 97.96% from the second cycle, respectively.