Synergistic action of spatially self-reconfiguring bilayer lithiophilic alloys and inorganic passivation layers for enhancing Li metal anode performance

Abstract

Li metal is regarded as a promising anode due to its high energy density and low redox potential. However, dendrite growth and electrolyte–lithium reactions lead to poor cycling stability of Li anodes, which hinders the practical application of Li metal anodes (LMAs) in high-energy rechargeable Li batteries. Herein, we envisage a unique “sandwich” anode of the Mg–Zn alloy uniformly confined between graphene oxide (GO) and Li foil. During the Li plating/stripping cycle, magnesium migrates from the Mg–Zn interlayer to the Li anode, forming a layered Li/Li₃Mg₇–LiZn/GO three-dimensional modified layer. The downward migrating Li–Mg alloy not only induces uniform deposition of Li but also serves as a binder to reduce the contact resistance between the electrode and the modification layer. The lithiophilic spherical Li–Zn alloy layer provides a large amount of deposition space for Li, thus accommodating volume changes during repeated Li plating/stripping processes. Meanwhile, the GO effectively decreases the contact of the electrolyte with fresh Li, which minimizes the continuous depletion of Li. Consequently, the protected Li metal anode delivers stable and dendrite-free cycling performance at 1 mA cm⁻² for over 2200 h. A full cell utilizing the LiFePO₄ cathode exhibits a stable voltage profile with low polarization for over 400 cycles at 2C, with a capacity decay rate of 0.052% per cycle.