A novel oxygen vacancy introduced microstructural reconstruction of SnO 2-graphene nanocomposite: Demonstration of enhanced electrochemical performance for sodium storage

摘要

This paper reported an oxygen vacancy contained SnO2-graphene nanocomposite (OVs-SnO2-Gr), which was prepared by annealing SnO2-graphene nanocomposite in 3?vol% H2/Ar atmospheres. It demonstrated with a high reversible capacity of around 510?mAh g?1after 300 cycles at a current density of 40?mA?g?1, and an impressive reversible rate performance of 391?mAh g?1can be obtained even at a high current density of 1200?mA?g?1when applied as anode for sodium storage. Evidenced by a new phase of Na2SnO3during sodium storage reactions, it is found that sodium can insert into crystal lattice of oxygen vacancy contained SnO2. Moreover, sodium insertion could arouse a novel structural reconstruction and introduce amorphous phase SnO2, which promotes the surface-controlled reaction process and Na+diffusion rates, and enables a good rate performance. Additionally, the H2/Ar annealing process increases overall conductivity of electrodes, which further reduces the barrier of Na+diffusion. It is believe that the as-prepared OVs-SnO2-Gr is a promising anodes for Na-ion batteries with outstanding electrochemical performance.