A reactive wetting strategy improves lithium metal reversibility

Abstract

The cycling of lithium metal (Li0) anode is often accompanied by irregular lithium plating/stripping, leading to poor Li0 reversibility, and posing a grand challenge to constructing reliable Li0 batteries. Hereby, we report a reactive wetting strategy to enable conformal and highly reversible Li0 plating/stripping through a lithium-reactive substrate. The reactive wetting, smooth nucleation, and conformal growth behaviors of Li0 are visualized through in-situ transmission electron microscopy, ex-situ scanning electron microscope, and in-situ optical microscope characterizations. Based on the reactive wetting substrate, high average Coulombic efficiencies (99.0% at 0.5 mA cm−2 for 400 cycles) are realized for Li0 anodes. By pre-plating Li0 into the reactive wetting substrate as anodes and leveraging LiFePO4 as cathodes, high capacity retention (76.0% after 200 cycles in low N/P ratio conditions) is also achieved in the as-constructed Li0 full cells. This work establishes a fundamental understanding of reactive wetting dynamics of Li0 and provides a drop-in solution to improving Li0 reversibility.