Rationally Integrating 2D Confinement and High Sodiophilicity toward SnO 2 /Ti 3 C 2 T x Composites for High-Performance Sodium-Metal Anodes.

The metallic sodium (Na) is characterized by high theoretical specific capacity, low electrode potential and abundant resources, and its advantages manifests itself as a promising candidate anode of sodium metal batteries (SMBs). However, the vaporization during the plating/stripping or uncontrolled growth of sodium dendrites in sodium metal anodes (SMAs) has posed major challenges to its practical applications. To address this issue, here, the SnO 2 /Ti 3 C 2 T x composite is rationally fabricated, in which sodiophilic SnO 2 nanoparticles are in situ dispersed on the 2D Ti 3 C 2 T x , providing the acceptor sites of Na +  that can control vaporization and dendrites. The SnO 2 /Ti 3 C 2 T x composite anode exhibits smooth and homogeneous morphology after Na-metal deposition cycles, stable Coulombic efficiency (CE) of half cells, long stable cycles of symmetric cells due to highly sodiophilic sites, and confinement effect. In addition, the full cells assembled with Na 0.6 MnO 2 also show excellent rate performance and cycling performance. These discoveries demonstrate the effectiveness of the acceptor sites and the confinement effect provided by the SnO 2 /Ti 3 C 2 T x composite, and thus provide an additional degree of freedom for designing SMBs.