Ultra-small tin dioxide coated with double carbon to achieve low strains and stable sodium storage

Tin dioxide as a kind of conversion-alloying-type anode material holds great promise for sodium ion anode material due to its large theoretical capacity, low working potential advantages, Nonetheless, its practical application been significantly hammered by the slow reaction kinetics and volume expansion problem during the cyclic process. Hence double carbon coating strategy and nanoengineering is employed to prepared SnO 2 @C/rGO composites as SIBs anodes. The ultra-small size of SnO 2 can significantly reduce the internal strain, shorten the ion diffusion distance, and improve the low-reversible conversion reaction and coulombic efficiency (CE). The structural design of the double carbon coated further improves the electrical conductivity and structural stability of the composite. It was demonstrated by XRD refinement that SnO 2 @C/rGO has low strain which enhances the reaction kinetics and realizes high reversible capacity during charging and discharging. The dual‑carbon structure is able to maintain the specific capacity of 316.8 mAh/g at 1.0 A/g after 1000 cycles, and at the same time, it has excellent rate performance (231.2 mAh/g at 5.0 A/g). This provides a new insight into the application of modified materials with double carbon coated to sodium-ion battery anode.