Hierarchical Carbon@SnS2 Aerogel with "Skeleton/Skin" Architectures as a High-Capacity, High-Rate Capability and Long Cycle Life Anode for Sodium Ion Storage.

Developing high-performance electrode materials with high energy and long-term cycling stability is a hot topic and of great importance for sodium ion batteries (SIBs). In this work, a highly porous carbon/tin sulfide aerogel with a "skeleton/skin" morphology (SSC@SnS2) has been developed and further used as a binder-free anode for SIBs. This SSC@SnS2 electrode delivers a high specific capacity of 612 mA h g-1 at 0.1 A g-1, a good rate capability, and a long-term cycling stability up to 1000 times with an average Coulombic efficiency of ∼99.9%. Meanwhile, this SSC@SnS2 aerogel also achieves a stable cycling performance even at a high current density up to 5.0 A g-1. The fast-yet-stable sodium ion storage performance of the prepared SSC@SnS2 aerogel can be ascribed to the reasons that (i) the carbon nanofiber/graphene skeleton provides unimpeded pathways for the rapid transfer of electrons; (ii) thin SnS2 skin with nonaggregated morphology can provide a great number of active sites for sodium ion storage; (iii) the porous structure of the SSC@SnS2 aerogel ensures a rapid penetration of electrolyte and can further accommodate the volume expansion of active SnS2 nanoflakes; and (iv) the intermediate product of Na15Sn4 alloy contributes greatly to the sodium ion storage performance of the SSC@SnS2 aerogel. The excellent electrochemical performances coupling with the unique structural features of this SSC@SnS2 aerogel make it a promising anode candidate for SIBs.