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.