Ultrathin and Air-Stable Lithium Metal Anodes with Superlong Cycling Life in Ether/Ester-Based Electrolytes

Ultrathin and air-stable Li metal anodes hold great promise toward high-energy and high-safety Li metal batteries (LMBs). However, the application of LMBs is technically impeded by existing Li metal anodes with large thickness, high reactivity, and poor performance. Here, we developed a novel and scalable approach for the construction of a 10-μm-thick flexible and air-stable Li metal anode by conformally encapsulating Li within a multifunctional VN film. Specifically, the highly lithiophilic VN layer guides a uniform deposition of Li, while abundant and multilevel pores arising from assembly of ultrathin nanosheets enable a spatially confined immersion of metallic Li, thus ensuring an ultrathin and sandwiched Li anode. More impressively, the strong hydrophobicity of VN surface can effectively improve the stability of anode to humid air, whereas the highly conductive framework greatly boosts charge transfer dynamics and enhances Li utilization and high-rate capability. Benefiting from such fascinating features, the constructed Li-VN anode exhibits ultrastable cycling stability in both ether (2500 h) and carbonate (900 h) electrolytes, respectively. Moreover, even exposed to ambient air for 12 h, the anode still can retain ~78% capacity, demonstrating excellent air-defendable capability. This work affords a promising strategy for fabricating high-performance, high-safety, and low-cost LMBs.