Two-pronged approach to regulate Li etching for a stable anode

Different carbon networks have been routinely used to modify Li anodes, which results in uniform nucleation on carbon materials. However, less attention is paid to the etching behavior of the Li metal under a modification layer. In this work, a failure analysis of a Li anode modified by an N-doped carbon nanofiber (CNF) demonstrates that pitting of the Li substrate is related to the final polarization of anode after relatively long cycling. A new approach is aimed at further improving the stability of a Li anode for long-period plating/stripping. The two-pronged approach combines a superficial SnOx decoration on the CNF and a plate-shell of Sn on the Li substrate that improves the electrochemical stability of Li. The superficial SnOx particles on the CNF induces the uniform deposition of Li on the CNF surface via a superficial alloying effect. The in situ formation of Li13Sn5 induces planar etching/growth of the Li substrate that improves the areal current density by two orders of magnitude. The two-pronged approach modified cells shows reduced polarization under a current density of 3 mA/cm(2) and 5 mA/cm(2) for 900 and 600 cycles, respectively. The two-pronged approach is also demonstrated by a full battery assembly with LiFePO4.