An Ultrastrong Double-Layer Nanodiamond Interface for Stable Lithium Metal Anodes

Effective stabilization of lithium metal has been hindered by the exacting requirements for the protection layer. Among all materials, the mechanical strength and electrochemical inertness of diamond is a prime candidate for lithium stabilization. Herein, we successfully rendered this desirable material compatible as lithium metal interface, which strictly satisfied the critical requirements. Our interface possessed the highest modulus among all the lithium coatings (>200 GPa), which can effectively arrest dendrite propagation. Since pinholes are the major failure mechanisms of artificial interfaces, a novel double-layer design was proposed to enhance the defect tolerance, enabling uniform ion flux and mechanical properties as confirmed by both simulation and experiments. Thanks to the multifold advantages of our interface design, high Coulombic efficiency of >99.4% was obtained at 1 mA cm−2; and more than 400 stable cycles were realized in prototypical lithium-sulfur cells with limited lithium, corresponding to an average anode Coulombic efficiency of >99%.