Three‐Layer Structured SnO2@C@TiO2 Hollow Spheres for High‐Performance Sodium Storage

The unsatisfactory conductivity and large volume variation severely handicap the application of SnO2 in sodium‐ion batteries (SIBs). Herein, we design unique three‐layer structured SnO2@C@TiO2 hollow spheres to tackle the above‐mentioned issues. The hollow cavity affords empty space to accommodate the volume variation of SnO2, while the C and TiO2 protecting shells strengthen the structural integrity and enhances the electrical conductivity. As a result, the three‐layer structured SnO2@C@TiO2 hollow spheres demonstrate enhanced Na storage performances. The SnO2@C@TiO2 manifests a reversible capacity two times to that of pristine SnO2 hollow spheres. In addition, Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO2@C@TiO2 hollow spheres. This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.