Engineering the Solid–Electrolyte Interphase via NO ₃ ⁻ Coordination at Open Metal Sites in HKUST‐1 for Stable Lithium Metal Anodes

Metal-organic frameworks (MOFs) are promising hosts for quasi-solid electrolytes (QSEs) by integrating liquid electrolytes (MOF@LE QSEs), yet stabilizing lithium metal anodes (LMAs) to enhance electrochemical performance remains a challenge. Here, we introduce a strategy leveraging open metal sites (OMSs) in HKUST-1 (Cu₃(BTC)₂) combined with LiNO₃ to tailor solid electrolyte interphase (SEI) chemistry and lithium deposition. OMSs in HKUST-1 anchor NO₃ ^- and promote LiNO₃ dissociation, enriching SEI with nitrogen-containing inorganic compounds and enabling uniform and spherical lithium morphology. Consequently, LMAs with LiNO₃-incorporated HKUST-1 membrane QSE (HM-LN QSE) achieve a critical current density of 2.7 mA cm^-2, with stable lithium plating/stripping over 650 h at 0.2 mA cm^-2 and more than 300 h at 0.5 mA cm^-2. Moreover, LiLiFePO₄ cells assembled with HM-LN QSEs delivere a discharge capacity of 81.2 mAh g^-1 at 5 C and retain 81.2% capacity after 350 cycles at 2 C, demonstrating superior electrochemical stability and performance. This innovative MOF-based approach significantly enhances SEI stability and LMA performance, advancing lithium metal battery technology.