Li+ diffusion kinetics of SnS2 nanoflowers enhanced by reduced graphene oxides with excellent electrochemical performance as anode material for lithium-ion batteries

Abstract

SnS2 nanosheet (NS), SnS2 nanoflower (NF) and SnS2NF@reduced graphene oxide (rGO) were synthesized by hydrothermal method. When used as anode materials for lithium-ion batteries (LIBs), SnS2NF@rGO exhibits reversible specific capacities of 525 mAh/g at 0.5C after 360 cycles and 412.5 mAh/g at 2.0C, which are significantly enhanced Li storage performance over SnS2NS and SnS2NF. The detailed electrochemical impedance spectroscopy (EIS) analysis were found that SnS2NF@rGO nanocomposite exhibits much reduced internal resistance originated from the decreasing Warburg factor. The electronic conductivity of the cycled SnS2NF@rGO is about three times more than that of cycled SnS2NS and SnS2NF. More importantly, the Li+ diffusion coefficients DLi+ were calculated using the galvanostatic intermittent titration technique (GITT) method, indicating SnS2NF@rGO demonstrated much enhanced Li+ diffusion kinetics than that of electrodes without rGO additives. This means that SnS2NF@rGO is more suitable to be applied as anode materials for LIBs because the electrochemical performance was enhanced by the improved ionic transport properties, resulting from the increased electronic conductivity by the addition of two-dimensional layer structure rGO with superior electronic conductivity. This study could help us understanding how electronic conductivity contributed to ionic transport kinetics in electrochemical energy storage and conversion (EESC).