Synergistic fluorine–nitrogen interfaces enabling stable high-voltage sulfide-based all-solid-state lithium metal batteries

Sulfide-based all-solid-state lithium metal batteries (ASSLMBs) are promising for high-energy-density and safe energy storage. But the poor compatibility of sulfide electrolytes with both high-voltage cathodes and lithium metal anodes hinders their practical application. Here, we disclose a fluorine-nitrogen synergistic interfacial engineering strategy by modifying Li_5.5PS_4.5Cl_1.5 (LPSC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The modified LPSC electrolyte shows a high ionic conductivity of 2.88 mS/cm. Moreover, LiTFSI induced dual-functional interphases, a fluorine-rich CEI (LiF/Li<em>_x</em>PO<em>_y</em>F<em>_z</em>) and a fluorine-nitrogen composite SEI (Li₃N/LiF/Li<em>_x</em>PO<em>_y</em>F<em>_z</em>), contributing to high oxidation stability (LiNi_0.8Co_0.1Mn_0.1O₂//LiIn battery retains 107% capacity retention after 13000 cycles at 15 C) and excellent lithium dendrite inhibition ability (Li//Li: CCD 3.4 mA/cm², stably cycling 2600 h at 0.5 mA/cm²). As a result, the LiNi_0.8Co_0.1Mn_0.1O₂//Li cell with modified electrolyte demonstrates 1000 stable cycles at a high cut-off voltage of 4.5 V and wide-temperature adaptability (-20~50 ℃). This work shows a facile and effective method for constructing long-life high-energy-density sulfide based ASSLMBs.