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 (3579 mAh/g), which is beyond the limit of conventional graphite anodes in lithium (Li) ion batteries (LIBs). However, large volume changes during the lithiation/delithiation process and 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 AlF₃ and PAA, a LiF-rich SEI layer with robust physicochemical properties is uniformly formed on the Si anode. As a result, the LPL coated Si (LPL@Si) anodes exhibit outstanding electrochemical properties in Li metal cell tests. In addition, a full-cell prepared with the LPL@Si anode and LiNi_0.8Co_0.1Mn_0.1O₂ 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.