Ultrafine tin oxide on reduced graphene oxide as high-performance anode for sodium-ion batteries

Highlights: • A nanohybrid based on ultrafine SnO₂ and few-layered rGO has been prepared. • The nanohybrid exhibits excellent electrochemical Na-storage properties. • The rGO supplies combined conducting, buffering and dispersing effects. - Abstract: Na-ion Battery is attractive alternative to Li-ion battery due to the natural abundance of sodium resource. Searching for suitable anode materials is one of the critical issues for Na-ion battery due to the low Na-storage activity of carbon materials. In this work, we synthesized a nanohybrid anode consisting of ultrafine SnO₂ anchored on few-layered reduced graphene oxide (rGO) by a facile hydrothermal route. The SnO₂/rGO hybrid exhibits a high capacity, long cycle life and good rate capability. The hybrid can deliver a high charge capacity of 324 mAh g_SnO2⁻¹ at 50 mA g⁻¹. At 1600 mA g⁻¹ (2.4C), it can still yield a charge capacity of 200 mAh g_SnO2⁻¹. After 100 cycles at 100 mA g⁻¹, the hybrid can retain a high charge capacity of 369 mAh g_SnO2⁻¹. X-ray photoelectron spectroscopy, ex situ transmission electron microscopy and electrochemical impedance spectroscopy were used to investigate the origin of the excellent electrochemical Na-storage properties of SnO₂/rGO