A comparative investigation on the effects of nitrogen-doping into graphene on enhancing the electrochemical performance of SnO2/graphene for sodium-ion batteries

Abstract

SnO₂/nitrogen-doped graphene nanohybrids have been synthesized by an in situ hydrothermal method, during which the formation of SnO₂ nanocrystals and nitrogen doping of graphene occur simultaneously. The as-prepared SnO₂/nitrogen-doped graphene nanohybrids exhibit enhanced electrochemical performance for sodium-ion batteries compared to SnO₂/graphene nanocomposites. A systematic comparison between SnO₂/nitrogen-doped graphene nanohybrids and the SnO₂/graphene counterpart as anode materials for sodium-ion batteries has been conducted. The comparison is in a reasonable framework, where SnO₂/nitrogen-doped graphene nanohybrids and the SnO₂/graphene counterpart have the same SnO₂ ratio, similar SnO₂ crystallinity and particle size, close surface area and pore size. The results clearly manifest that the improved electron transfer efficiency of SnO₂/nitrogen-doped graphene due to nitrogen-doping plays a more important role than the increased electro-active sites within graphene network in enhancing the electro-activity of SnO₂/nitrogen-doped graphene nanohybrids compared to the SnO₂/graphene counterpart. In contrast to the previous reports which often ascribe the enhanced electro-activity of nitrogen-doped graphene based composites to two nitrogen-doping effects (improving the electron transfer efficiency and increasing electro-active sites within graphene networks) in one single declaration, this work is expected to provide more specific information for understanding the effects of nitrogen-doping into graphene on improving the electrochemical performance of graphene based composites.