Towards reducing carbon content in silicon/carbon anodes for lithium ion batteries.

Conducting carbon is added to electrodes of lithium ion batteries (LIBs) to provide electrical conductivity. Because this carbon does not contribute to capacity, there is a drive towards decreasing its content with a goal of lowering the mass of the electrode. Reduced graphene oxide (RGO) has a high electrical conductivity, and is a potential alternative to traditionally used conductive carbon black (CB) in anodes for LIBs. Because of its high aspect ratio, RGO is expected to form a conducting network at lower volume loadings than CB. We report the use of this concept to significantly reduce carbon loading in silicon-carbon anodes for LIBs formed by emulsion-templating. Anodes with 1 wt% RGO and 14 wt% CB (15 wt% total carbon) showed specific capacities and capacity retentions that were comparable to anodes with 30 wt% CB with or without RGO. The capacity retention was significantly lower for anodes with 15 wt% total carbon that had no RGO. Cryo-SEM and SEM images, and electrochemical impedance spectroscopy, confirmed the formation of a conducting carbon network at 15 wt% total carbon loading when 1 wt% of the CB was replaced with RGO, and the lack of a well-connected network without the RGO. [ABSTRACT FROM AUTHOR]