Unlocking the Potential of Sparingly Soluble LiNO3 in Carbonate Electrolytes With Pyridine as a Carrier Cosolvent for 450 Wh Kg-1 High-Voltage Lithium Metal Batteries.

LiNO3 is a highly effective electrolyte additive for ether-based lithium metal batteries, but its extremely poor solubility in carbonate electrolytes has long restricted its application in high-voltage high-energy-density systems. In this study, we develop a pyridine carrier cosolvent strategy to efficiently dissolve LiNO3 in carbonate electrolytes. Pyridine coordinates with Li+ to enter the solvation shell, weakening Li+-carbonate interactions to promote LiNO3 dissolution and enable NO3 - participation in interphase formation. The coordination effect also suppresses the intrinsic high reactivity of pyridine, realizing its controllable interfacial decomposition. The synergistic decomposition of pyridine and LiNO3 constructs compact, inorganic-dominated, rigid-flexible interpenetrating electrode-electrolyte interphases rich in Li3N, LiNxOy, and LiF with high mechanical strength. Benefiting from the optimized interphases, Li||Cu cells deliver a Coulombic efficiency (CE) of 97.3% at 2 mA cm-2, and 4.5 V Li||NCM90 cells show outstanding cycling stability under practical thin-lithium and lean-electrolyte conditions. Remarkably, 5.6 Ah pouch cells achieve an energy density up to 453 Wh kg-1 with 95.5% capacity retention after 50 cycles. This work offers a facile approach for utilizing sparingly soluble functional additives and promotes the development of high-voltage, high-energy-density lithium metal batteries.