An artificial hybrid interphase for an ultrahigh-rate and practical lithium metal anode

Abstract

The solid electrolyte interphase (SEI) layer is pivotal for stable lithium (Li) metal batteries especially under a high rate. However, the mechanism of Li⁺ transport through the SEI has not been clearly elucidated to build robust Li anodes for practical Li metal batteries. Herein, an artificial hybrid SEI layer consisting of lithium-antimony (Li₃Sb) alloy and lithium fluoride (LiF) is constructed to explore the ion diffusion behaviors within the SEI. As evidenced theoretically and experimentally, Li₃Sb is identified as a superionic conductor for Li⁺ transport and as an interfacial stabilizer for the SEI layer while the LiF component with superior electron-blocking capability reduces the electron tunneling from the Li anode into the SEI, resulting in uniform dendrite-free Li deposition at the SEI/Li interface and stable Li plating/stripping behaviors at an ultrahigh rate of 20 mA cm⁻². A practical 325.28 W h kg⁻¹ pouch cell is well demonstrated under a high sulfur loading of 6 mg cm⁻² and a low electrolyte/sulfur ratio of 3 μl mg⁻¹. This work uncovers the internal mechanism of Li⁺ transport within the SEI component, and provides an avenue to stabilize the Li anode under practical high-rate conditions.