Freeze-Drying-Assisted Synthesis of Porous SnO2/rGO Xerogels as Anode Materials for Highly Reversible Lithium/Sodium Storage

Three-dimensional porous SnO2/rGO xerogels with superior cycling performance in lithium-ion batteries (LIBs) and sodiumion batteries (SIBs) are fabricated through a freeze-dryingassisted method. SnO2 nanoparticles (5 nm in diameter) are homogeneously attached to the surface of graphene sheets without self-aggregation. The heterostructured SnO2/rGO xerogel possesses numerous micron-sized pores that can efficiently buffer the volumetric change of SnO2 during the charge/discharge process and provide multidimensional channels, improving the conductivity between active materials and electrolyte. The SnO2/rGO xerogel exhibits excellent electro-chemical performance, both in LIBs and SIBs, owing to its particular porous structure. For LIBs, it delivers a high initial discharge capacity of 1670.5 mAhg in the first cycle and remains at 1139.4 mAhg(-1) after 166 cycles at a current density of 0.1 Ag-1. The SnO2/rGO xerogel also delivers a high discharge capacity of 189.4 mAhg without capacity loss over 266 cycles at a current density of 0.5 Ag-1 for SIBs. The SnO2/rGO xerogel can be used as an electrode material in both LIBs and SIBs, and can maintain an excellent rate performance and cyclic performance, owing to the abundant porosity and high conductivity.