Stabilizing a Si Anode via an Inorganic Oligomer Binder Enabled by Robust Polar Interfacial Interactions

Abstract

Exploiting macromolecule binders has been demonstrated as an effective approach to stabilize a Si anode with a huge volume change. The macromolecule polymer binders with vast intra/intermolecular interactions lead to an inferior dispersion of binders on a Si active material. Herein, a potassium triphosphate (PTP) inorganic oligomer was exploited as a robust binder to alleviate the problem of capacity fading in Si-based electrodes. PTP has abundant P–O– bonds and P═O bonds, which can form strong ion–dipolar and dipolar–dipolar forces with a hydroxylated Si surface (Si–OH). Particularly, the PTP inorganic oligomer has a short-chain structure and high water solubility, resulting in a superior dispersion of the PTP binder on Si nanoparticles (nano-Si) to effectively enhance the mechanical stability of Si-based electrodes. Hence, the as-prepared Si-based anode exhibits obviously improved electrochemical performance, delivering a charge capacity of 1279.7 mAh g–1 after 300 cycles at 800 mA g–1 with a high capacity retention of 72.7%. Moreover, using the PTP binder, a dense Si anode can be achieved for high volumetric energy density. The success of this study shows that the PTP inorganic oligomer as a binder has great significance for future advanced binder research.