Mechanochemically Boosting Additive for Robust Si/C Anodes in High-Energy-Density Li-Ion Batteries

Abstract

Silicon (Si) is regarded as one of the most promising anode materials for Li-ion batteries (LIBs) owing to its high specific capacity of 3579 mAh g-1 and low redox potential. However, large volume changes in Si during lithiation/delithiation cycles lead to microcrack formation in the electrode and rupture of the solid electrolyte interphase (SEI) layer, resulting in poor cycling stability. In this regard, Si/carbon (Si/C) composites have been widely explored to mitigate the volume changes in Si and increase the Li-ion kinetics. However, the mechanochemically unstable SEI layer is still challenging for the development of high-energy-density Si/C anodes. In this study, polyvinylpyrrolidone (PVP) is introduced as a mechanochemically boosting electrode additive (MBEA) to enhance the chemical and mechanical stability as well as the electrochemical performance of Si/C composite anodes in LIBs. PVP can stabilize the anode interface by forming a robust inorganic-rich SEI layer, which improves the Li-ion kinetics owing to its chemical stability and mechanical integrity. Furthermore, PVP on the surface of Si/C composite anodes enhances the binding affinity, including the adhesion and cohesion properties of the active materials. In these regards, the Si/C anodes with MBEA (Si/C-MBEA) exhibit excellent electrochemical performance with alleviated volume changes compared with the pristine Si/C anode. This study presents a facile and practical approach for the development of high-performance Si-based anodes for next-generation LIBs.