Dual-Function Alloying Nitrate Additives Stabilize Fast-Charging Lithium Metal Batteries.

Lithium metal is regarded as the "holy grail" of lithium-ion battery anodes due to its exceptionally high theoretical capacity (3800 mAh g -1 ) and lowest possible electrochemical potential (-3.04 V vs Li/Li + ); however, lithium suffers from the dendritic formation that leads to parasitic reactions and cell failure. In this work, we stabilize fast-charging lithium metal plating/stripping with dual-function alloying M -nitrate additives ( M : Ag, Bi, Ga, In, and Zn). First, lithium metal reduces M , forming lithiophilic alloys for dense Li nucleation. Additionally, nitrates form ionically conductive and mechanically stable Li 3 N and LiN x O y , enhancing Li-ion diffusion through the passivation layer. Notably, Zn-protected cells demonstrate electrochemically stable Li||Li cycling for 750+ cycles (2.0 mA cm -2 ) and 140 cycles (10.0 mA cm -2 ). Moreover, Zn-protected Li||Lithium Iron Phosphate full-cells achieve 134 mAh g -1 (89.2% capacity retention) after 400 cycles (C/2). This work investigates a promising solution to stabilize lithium metal plating/stripping for fast-charging lithium metal batteries.