Lithophilic yet Inert Interfaces Strategy for Stable Lithium Metal Anodes.

Abstract

In lithium (Li) metal batteries, lithophilic materials play an essential role in stabilizing Li metal anodes. However, it is very difficult to attenuate the reactivity with Li while maintaining their lithophilicity. Herein, we propose a "lithophilic yet inert interfaces strategy" to stabilize Li metal anodes. That is, the chemically/mechanically stabilized composite BP@MOFs are formed by in situ growth of metal-organic frameworks (MOFs) on the surface of black phosphorus (BP), which can be used as an artificial interface to stabilize Li metal anodes. Among them, the highly conductive porous MOFs provide enriched channels for the migration of Li-ion (Li⁺). A series of experiments and theoretic analysis are utilized to reveal that charge transfer between BP and the metal ions reduces the electron density on the BP surface, thereby weakening its reactivity while maintaining its lithophilicity. It inhibits excess Li consumption and suppresses the excessive expansion of the BP volume in the continuous exfoliation/deposition process. Accordingly, the protected Li anodes can undergo reversible Li plating/stripping over 2000 h at a current density of 1 mA cm^-2. Coupling the BP@MOF-Li with a sulfur cathode, the Li-S cell shows an excellent capacity retention of 88.1% after 500 cycles, with a fading rate of less than 0.024% per cycle.