Binding Sulfur-Doped Nb2O5 Hollow Nanospheres on Sulfur-Doped Graphene Networks for Highly Reversible Sodium Storage

Orthorhombic Nb2O5 (T-Nb2O5) has recently attracted great attention for its application as an anode for sodium ion batteries (NIBs) owing to its patulous framework and larger interplanar lattice spacing. Sulfur-doped T-Nb2O5 hollow nanospheres (diameter:180 nm) uniformly encapsulate into sulfur-doped graphene networks (denoted: S-Nb2O5 HNS@S-rGO) using hard template method. The 3D ordered porous structure not only provides good electronic transportation path but also offers outstanding ionic conductive channels, leading to an improved sodium storage performance. In addition, the introduction of sulfur to graphene and Nb2O5 leads to oxygen vacancy and enhanced electronic conductivity. The sodium storage performance of S-Nb2O5 HNS@S-rGO is unprecedented. It delivers a reversible capacity 215 mAh g(-1) at 0.5 C over 100 cycles. In addition, it also possesses a great high-rate capability, retaining a stable capacity of 100 mAh g(-1) at 20 C after 3000 cycles. This design demonstrates the potential applications of Nb2O5 as anode for high performance NIBs.