Reduced\nGraphene Oxide/Tin–Antimony Nanocomposites\nas Anode Materials for Advanced Sodium-Ion Batteries

Abstract

Reduced graphene oxides loaded with\ntin–antimony alloy (RGO-SnSb)\nnanocomposites were synthesized through a hydrothermal reaction and\nthe subsequent thermal reduction treatments. Transmission electron\nmicroscope images confirm that SnSb nanoparticles with an average\nsize of about 20–30 nm are uniformly dispersed on the RGO surfaces.\nWhen they were used as anodes for rechargeable sodium (Na)-ion batteries,\nthese as-synthesized RGO-SnSb nanocomposite anodes delivered a high\ninitial reversible capacity of 407 mAh g^–1, stable\ncyclic retention for more than 80 cycles and excellent cycle stability\nat ultra high charge/discharge rates up to 30C. The significantly\nimproved performance of the synthesized RGO-SnSb nanocomposites as\nNa-ion battery anodes can be attributed to the synergetic effects\nof RGO–based flexible framework and the nanoscale dimension\nof the SnSb alloy particles (<30 nm). Nanosized intermetallic SnSb\ncompounds can exhibit improved structural stability and conductivity\nduring charge and discharge reactions compared to the corresponding\nindividuals (Sn and Sb particles). In the meantime, RGO sheets can\ntightly anchor SnSb alloy particles on the surfaces, which can not\nonly effectively suppress the agglomeration of SnSb particles but\nalso maintain excellent electronic conduction. Furthermore, the mechanical\nflexibility of the RGO phase can accommodate the volume expansion\nand contraction of SnSb particles during the prolonged cycling, therefore,\nimprove the electrode integrity mechanically and electronically. All\nof these contribute to the electrochemical performance improvements\nof the RGO-SnSb nanocomposite-based electrodes in rechargeable Na-ion\nbatteries.