Synergistically enhanced LiF–rich protective layer for highly stable silicon anodes

Silicon (Si) is considered as one of the most promising anode materials with an extremely high specific capacity of 3579 mAh/g, which is beyond the limit of conventional graphite anodes in lithium (Li) ion batteries (LIBs). However, the large volume changes during the lithiation/delithiation process and the formation of an unstable solid electrolyte interface (SEI) layer hinder the practical application of Si anodes. To address these issues, constructing a stable protective layer at the interface between anode and electrolyte is a desirable strategy. In this study, a LiF-rich SEI inducing protective layer (LPL) comprising aluminum fluoride (AlF3) and poly(acrylic acid) (PAA) is introduced onto Si anode to construct a stable LiF–rich SEI layer and mitigate the volume changes of the Si anodes during cycling. Owing to the synergetic effects of the AlF3 and the PAA in the LPL, a LiF-rich SEI layer with robust physicochemical properties is uniformly formed at the interface between the anode and electrolyte. As a result, the LPL coated Si (LPL@Si) anode exhibits outstanding electrochemical properties. A full-cell prepared with the LPL@Si anode and LiNi0.8Co0.1Mn0.1O2 as a cathode exhibits an excellent cycling performance and mitigated volume changes, demonstrating the potential of this strategy to protect the Si anodes for the development of high-energy–density LIBs.