Design Principles of LiNO3 Inhibitor to Trigger Bilayer SEI and Wield Interface Reation for Wide-Temperature-range Lithium Metal Anodes

LiNO3 is a widely used lithium salt additive in high specific energy lithium metal batteries due to its ability to form a uniform and compact solid electrolyte interphase (SEI). However, the repeated rupture and healing of SEI can rapidly deplete LiNO3, leading to cell failure. In this study, different metal films (Zn, Ag, Sn, In, and Cu) were sputtered onto commercial polypropylene (PP) separators (Z-PP, A-PP, S-PP, I-PP, and C-PP) using DC magnetron sputtering. This process formed a bilayer SEI structure that not only promoted uniform lithium deposition and extraction but also acted as an inhibitor for LiNO3 depletion. Among these, the A-PP separator demonstrated remarkable performance, achieving a 99.02 % Average Coulombic Efficiency (ACE) after 605 cycles and an ultralong lifespan of up to 2700 h (1350 cycles). Density Functional Theory (DFT) calculations indicate that Ag nanoparticles provide optimal adsorption and regulate the decomposition of LiNO3, aligning with the experimental findings. The study also evaluated pouch cells with various cathodes, including LiFePO4 (LFP), LiNi0.8Co0.1Mn0.1O2 (NCM811), and LiNi0.6Co0.2Mn0.2O2 (NCM622), demonstrating the universal applicability of the APP strategy. Additionally, the NCM622 pouch cells with A-PP separators operated effectively for 200 cycles even at -15 degrees C, further validating the robustness of this approach.