Smart hybridization of Sn2Nb2O7/SnO2@3D carbon nanocomposites with enhanced sodium storage performance through self-buffering effects

Abstract

Proper hybridization of different kinds of materials into tailored structures is a highly effective way to fabricate advanced anode materials for sodium ion batteries. In this work, mulberry-like Sn₂Nb₂O₇/SnO₂ nanoparticles (≈40 nm) homogeneously anchored on 3D carbon networks (indicated with M-Sn₂Nb₂O₇/SnO₂@3DC) were prepared through a facile one-step high temperature calcination technique. In the constructed architecture, Sn-based materials with high specific capacity, Nb-based materials with excellent structural stability and 3D carbon networks with high electron conductivity were well integrated into a smart system. The 3D carbon networks not only act as a buffer material to prevent pulverization, but also serve as a conductive matrix, while the in situ formed amorphous Na_xNb₂O₅ substrate from Sn₂Nb₂O₇ can restrain the volume variation to prevent Sn from aggregation and pulverization during cycling. This unique “self-buffering” effect can remarkably enhance the structural integrity of the electrode. As a result, when tested as a sodium ion battery anode, the as-synthesized hybrid exhibited relatively high reversible capacity (300 mA h g⁻¹ at the current density of 100 mA g⁻¹), outstanding high-rate capability (119 mA h g⁻¹ even at the high current density of 10 A g⁻¹) and extremely long cycling stability (130 mA h g⁻¹ at the current density of 5.0 A g⁻¹ for 5000 cycles). Such excellent electrochemical performance demonstrates the potential use of the Sn₂Nb₂O₇/SnO₂@3D carbon composite as an anode material for high-performance sodium-ion batteries.