Understanding the effect of different polymeric surfactants on enhancing the silicon/reduced graphene oxide anode performance

Silicon-based lithium-ion battery anodes have brought encouraging results to the current state-of-the-art battery technologies due to their high theoretical capacity, but their large-scale application has been hampered by a large volume change (>300%) of silicon upon lithium insertion and extraction, which leads to severe electrode pulverization and capacity degradation. Polymeric surfactants directing the combination of silicon nanoparticles and reduced graphene oxide have attracted great interest as promising choices for accommodating the huge volume variation of silicon. However, the influence of different polymeric surfactants on improving the electrochemical performance of silicon/reduced graphene oxide (Si/RGO) anodes remains unclear because of the different structural configurations of polymeric surfactants. Here, we systematically study the effect of different polymeric surfactants on enhancing the Si/RGO anode performance. Three of the most well-known polymeric surfactants, poly(sodium 4-styrenesulfonate) (PSS), poly(diallydimethylammonium chloride) (PDDA), and polyvinylpyrrolidone (PVP), were used to direct the combination of silicon nanoparticles and RGO through van der Waals interaction. The Si/RGO anodes made from these composites act as ideal models to investigate and compare how the van der Waals forces between polymeric surfactants and GO affect the final silicon anode performance from both experimental observations and theoretical simulations. We found that the capability of these three surfactants in enhancing long-term cycling stability and high-rate performance of the Si/RGO anodes decreased in the order of PVP > PDDA > PSS.