A novel microstructural reconstruction phenomenon and electrochemical performance of cactus-like SnO2/carbon composites as anode materials for Na-ion batteries

•Cactus-like SnO2/carbon was prepared by two step hydrothermal synthesis.•A structural reconstruction phenomenon was observed after battery cycling.•The sample is demonstrated with an enhanced cyclability as anode for Na battery.•The carbon component is proven to introduce a high quality SEI.

A hydrothermal synthesis and a subsequent carbon coating process have been used to prepare a cactus-like SnO2/carbon composite as anodes for Na-ion batteries. This composite was demonstrated with enhanced cyclability and outstanding electrochemical performance when used as anode for Na-ion batteries. It delivered an initial discharge capacity of 1259 mAh g−1, and then retained a high reversible capacity of around 500 mAh g−1 after 50 cycles at a current density of 20 mA g−1. When the current density increased to 1200 mA g−1, a reversible capacity of 120 mAh g−1 can be obtained. Comparing the difference of microstructures before and after cycling, it is found that the cactus-like SnO2/carbon composite presents a novel carbon coating introduced microstructural reconstruction phenomenon. Moreover, the carbon coating was proven to stabilize a spatial cactus structure and induce a high quality solid electrolyte interface (SEI) layer, which effectively enhanced the cyclablity of the cactus-like SnO2/carbon composite. It is believed that carbon coating is an effective way to improve the electrochemical performance of the cactus-like SnO2.