Hydrophobic lithium diffusion-accelerating layers enables long-life moisture-resistant metallic lithium anodes in practical harsh environments

Abstract

Rechargeable lithium metal batteries are deemed as "Holy Grail" in high energy storage systems. However, lithium anode suffers from Li dendrite growth resulted from sluggish ion diffusion and random spatial deposition. Meanwhile, the practical harsh anhydrous and oxygen-free assembly-environmental conditions also challenge their wide assembly and application. Herein, a universal hydrophobic lithium diffusion-accelerated artificial layer is proposed on Li surface to resist moisture corrosion, realizing uniform lithium diffusion/plating morphology in practical harsh environments. As a demo, the robust moist-air-stable polymer-LiF-alloy hybrid hierarchical layer is fabricated (MASPLA-Li), inheriting robust interfacial stability towards moist air as high as 50 RH%, which are comprehensively revealed by X-ray spectroscopy, electronic microscopy, time-of-flight second-ionic mass spectroscopy, and sum frequency generation spectroscopy. Systematic investigations of being moist air exposure treatment for different time are performed, and the moist-air-exposed MASPLA-Li anode reserves fast ion diffusion, extends the longer plating lifespan over 600 h with overpotential of ∼ 10 mV, and displays much higher Coulombic efficiency of 99.3%, significantly better than the little literature reports. Coupling with LiFePO4 and sulfur cathodes, the so-fabricated full cells also show remarkably improved utilization, cycling stability, and capacity retention at 5 C, showing the promising future in the practical application.