Synergistic effect of LixSi/LiN artificial interface and 3D framework for enabling Dendrite-free, long-life lithium metal anodes.

Lithium metal is highly favored as an ideal anode material in future high-capacity lithium batteries due to its appealing properties. Nevertheless, the implementation of lithium metal batteries (LMBs) is severely plagued by challenges such as instable solid electrolyte interface (SEI), uncontrolled growth of dendrite, and severe volume expansion. Herein, to address the aforementioned issues, an artificial SEI layer is fabricated, which is comprised of LixSi alloy and LiN. The in-situ generated LixSi/LiN interface is formed on the carbon fiber (denoted as CF/LixSi/LiN) through a spontaneous reaction between molten Li and SiN. Density functional theory (DFT) calculations reveal that LixSi alloy has low ion diffusion energy barrier, which facilitates the low nucleation overpotential of Li and enables homogeneous lithium deposition. LiN can further promote the rapid Li transport due to the excellent Li conductivity. In addition, the reserved 3D space effectively mitigates the volume change along cycling procedure. Owing to the synergistic effect of the LixSi/LiN protective layer and the 3D structure, the composite anode shows higher cycling stability with a lifetime of more than 3000 cycles at 1 mA cm. Furthermore, matched with commercial LiFePO (LFP) and LiNiCoMnO (NCM523) cathodes, the full cells also exhibit impressive electrochemical properties. This work introduces an ingenious approach for constructing stable lithium metal anodes and effective lithium metal batteries.