A first-principles study of self-healing binders for next-generation Si-based lithium-ion batteries

Silicon anodes typically suffer from poor intrinsic conductivity and dramatic volume change during charge/discharge cycles, which hinders their commercialization in high energy density lithium-ion batteries (LiBs). This issue can be alleviated by embedding particles of the active material in an adhesive matrix, such as a polymer binder, that can accommodate large volume changes during lithiation and delithiation. Several research efforts have aimed at enhancing the adhesive, elastic, electrical, and ionic properties of binders for use in silicon anodes. Therefore, stable silicon/polymer interfaces are crucial for the performance of high capacity silicon-based LiBs. In this research, we focused on the definition of the mechanisms that determine the adhesion properties of a couple of recently proposed self-healing polymers, on Si-surfaces. The structural and electronic properties as well as the energetics of boronic acid-doped polyaniline and polyvinyl alcohol monomers absorbed on Si (110) and Si (111) surfaces have been investigated through first-principles calculations based on the density functional theory. We showed that the coabsorption of these two monomers increases the absorption energy and in general improves the adhesion properties of both polymers on both Si-surfaces, especially on the Si (111) facet.