Interface engineering of Si-based anodes with fluorinated binder enabling lean-additive lithium-ion batteries

Abstract

Silicon (Si) is a promising alternative to graphite anode for increasing the energy density of litihum-ion batteries owing to its high theoretical capacity. However, the severe volume change of Si during cycling leads to unstable solid electrolyte interphase (SEI) growth, resulting in rapid capacity fading, particularly under lean-additive electrolyte conditions. In this study, we introduce an innovative approach to interface engineering of Si anodes using a fluorinated binder, a method that forms a stable and uniform lithium fluoride (LiF)-based SEI layer under lean-additive electrolyte conditions without the need for common additives. The LiF layer not only improves the structural stability of Si electrodes but also enhances the electrolyte stability, thereby preventing undesired SEI growth by electrolyte decomposition. Benefiting from this proposed binder, the Si-based anode retains a high reversible capacity (93.7 %) after 400 cycles at 0.9 A g−1 and the full cell, pairing with LiNi0.8Co0.1Mn0.1O2 cathode, delivers a high areal capacity of 4.23 mAh cm−2 (93.4 % retention) after 200 cycles under a lean-additive electrolyte (only 3 wt% additive). The interface stabilization by fluorinated binder provides insights into the rational design of a binder for the application of Si anodes in high-energy-density lithium-ion batteries.