Promoting homogeneous lithiation of silicon anodes via the application of bifunctional PEDOT:PSS/PEG composite binders

Abstract

Polymeric conducting binders have increasingly become a subject of significant research interest due to their dual roles as both a binder and a conducting agent. This dual functionality not only increases the proportion of active materials in the electrode but also elevates the volumetric energy density of current Li-ion batteries. In this study, we explore the potential of a composite of PEDOT:PSS and polyethylene glycol (PEG) as a high-performing binder for silicon anodes. This highly conductive PEDOT:PSS, enhanced by the addition of PEG polymer, displays exceptional electrochemical characteristics, including superior C-rate, Li-ion diffusivity performance, and extended cycle endurance. Of particular interest are the enhanced mechanical properties bestowed by the plasticizing effect of the PEG polymer. This improvement aids the Si anode in resisting pulverization during successive discharge and charge cycles. As a result, this enables extended cyclability without the creation of anode cracking. Additionally, the use of operando optical microscopy allows for the direct observation of lithiation kinetics within the PEDOT:PSS/PEG binder. This revealed a uniform color change with restrained volume expansion, demonstrating the successful operation of the binder. Consequently, the bifunctional PEDOT:PSS/PEG binder shows promise as a robust strategy for the next generation of high-performance lithium-ion battery binders.