High-Electron-Insulating Li ₂ O-Assisted Li ₃ N 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, Li 3 N with high Li + conductivity and Li 2 O 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 Li 3 N/Li 2 O-modified lithium anode (Li 3 N/Li 2 O–Li) was further elucidated by in situ Raman spectroscopy. Electrochemical measurements reveal that symmetric Li∥Li cells equipped with the Li 3 N/Li 2 O–Li electrode exhibit a Li + transference number of 0.403, surpassing those of Li 3 N–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 Li 3 N–Li and 94.69 Ω for bare Li. As a result, Li∥Li symmetric cells based on the Li 3 N/Li 2 O–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.