Two-dimensional lithiophilic YFδ enabled lithium dendrite removal for quasi-solid-state lithium batteries

Lithium metal batteries are regarded as promising alternatives to lithium ion batteries due to their high specific capacity. However, lithium dendrite growth during cycling causes safety problem and rapid capacity loss. Here, we report a composite Li anode composed (LYF) of metallic Li and trace amounts (1–2 wt%) of two-dimensional YFδ. The lithiophilic nature of YFδ enables its homogeneous dispersion in metallic lithium. The LYF electrode exhibits lower resistance, higher chemical and mechanical stability, and longer cycle life compared to bare Li electrode due to uniform Li stripping and plating with YFδ incorporation, which was confirmed by in-situ optical microscope observation. X-ray photoelectron spectroscopy reveals that LiF can in-situ form on the LYF electrode with reactions between Li and YFδ during cycling. The spontaneous reactions are clarified by density functional theory calculations. A quasi-solid-state cell with LYF anode, LiFePO4 cathode and cathode-supported solid electrolyte layer has been constructed with a soft interface constructed between Li anode and solid electrolyte by in-situ thermal polymerization. The cell shows a high initial discharge capacity of 147 mAh g−1 at 0.5 C at 60 °C and sustains a stable cycling over 50 cycles with the in-situ formed LiF-rich layer and soft interface.