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 SnO 2 in sodium‐ion batteries (SIBs). Herein, we design unique three‐layer structured SnO 2 @C@TiO 2 hollow spheres to tackle the above‐mentioned issues. The hollow cavity affords empty space to accommodate the volume variation of SnO 2 , while the C and TiO 2 protecting shells strengthen the structural integrity and enhances the electrical conductivity. As a result, the three‐layer structured SnO 2 @C@TiO 2 hollow spheres demonstrate enhanced Na storage performances. The SnO 2 @C@TiO 2 manifests a reversible capacity two times to that of pristine SnO 2 hollow spheres. In addition, Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO 2 @C@TiO 2 hollow spheres. This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.