Sustained Release-Driven Interface Engineering Enables Fast Charging Lithium Metal Batteries

LiNO₃ has attracted intensive attention as a promising electrolyte additive to regulate Li deposition behavior as it can form favorable Li₃N, LiN_xO_y species to improve the interfacial stability. However, the inferior solubility in carbonate-based electrolyte restricts its application in high-voltage Li metal batteries. Herein, an artificial composite layer (referred to as PML) composed of LiNO₃ and PMMA is rationally designed on Li surface. The PML layer serves as a reservoir for LiNO₃ release gradually to the electrolyte during cycling, guaranteeing the stability of SEI layer for uniform Li deposition. The PMMA matrix not only links the nitrogen-containing species for uniform ionic conductivity but also can be coordinated with Li for rapid Li ions migration, resulting in homogenous Li-ion flux and dendrite-free morphology. As a result, stable and dendrite-free plating/stripping behaviors of Li metal anodes are achieved even at an ultrahigh current density of 20 mA cm^-2 (>570 h) and large areal capacity of 10 mAh cm^-2 (>1200 h). Moreover, the Li||LiFePO₄ full cell using PML-Li anode undergoes stable cycling for 2000 cycles with high-capacity retention of 94.8%. This facile strategy will widen the potential application of LiNO₃ in carbonate-based electrolyte for practical LMBs.