Three‐Layer Structured SnO 2 @C@TiO 2 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 SnO2@C@TiO(2)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 TiO(2)protecting shells strengthen the structural integrity and enhances the electrical conductivity. As a result, the three-layer structured SnO2@C@TiO(2)hollow spheres demonstrate enhanced Na storage performances. The SnO2@C@TiO(2)manifests a reversible capacity two times to that of pristine SnO(2)hollow spheres. In addition,Ex situXRD reveals highly reversible alloying and conversion reactions in SnO2@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.