High-Electron-Insulating Li₂O-Assisted Li₃N for Highly Stable SEI Formation in High-Performance Li-S Batteries

Enhancing Li⁺ transport within the solid electrolyte interphase while simultaneously inhibiting electron conduction represents an effective strategy to suppress lithium dendrite formation and mitigate interfacial volume fluctuations during charge-discharge cycling, thereby improving the electrochemical performance of lithium metal anodes. In this work, Li₃N with high Li⁺ conductivity and Li₂O with strong electronic insulation were in situ coconstructed into an interwoven SEI architecture using 3-nitro-1,2,4-triazole as a dual nitrogen-oxygen precursor, guided by density functional theory calculations. The formation mechanism of the Li₃N/Li₂O-modified lithium anode (Li₃N/Li₂O-Li) was further elucidated by in situ Raman spectroscopy. Electrochemical measurements reveal that symmetric Li∥Li cells equipped with the Li₃N/Li₂O-Li electrode exhibit a Li⁺ transference number of 0.403, surpassing those of Li₃N-Li (0.334) and bare Li (0.234). In addition, the interfacial charge-transfer resistance is significantly reduced to 53.85 Ω, compared with 77.73 Ω for Li₃N-Li and 94.69 Ω for bare Li. As a result, Li∥Li symmetric cells based on the Li₃N/Li₂O-Li anode achieve an extended cycling lifetime of 800 h at 0.5 mA cm^-2 with 0.5 mAh cm^-2, more than 11 times longer than that of bare Li. Even under more demanding conditions (1 mA cm^-2, 1 mAh cm^-2), stable operation is maintained for 630 h.