Compact TiO₂@SnO₂@C heterostructured particles as anode materials for sodium-ion batteries with improved volumetric...

Sodium-ion batteries (SIBs) are promising candidates for large-scale energy storage. Increasing the energy density of SIBs demands anode materials with high gravimetric and volumetric capacity. To overcome the drawback of low density of conventional nanosized or porous electrode materials, compact heterostructured particles are developed in this work with improved Na storage capacity by volume, which are composed of SnO₂ nanoparticles loaded into nanoporous TiO₂ followed by carbon coating. The resulted TiO₂@SnO₂@C (denoted as TSC) particles inherit the structural integrity of TiO₂ and extra capacity contribution from SnO₂, delivering a volumetric capacity of 393 mAh cm^-3 notably higher than that of porous TiO₂ and commercial hard carbon. The heterogeneous interface between TiO₂ and SnO₂ is believed to promote the charge transfer and facilitate the redox reactions in the compact heterogeneous particles. This work demonstrates a useful strategy for electrode materials with high volumetric capacity.