Superfast Mass Transport of Na/K Via Mesochannels for Dendrite-Free Metal Batteries.

Fast ion diffusion in anode hosts enabling uniform distribution of Li/Na/K is essential for achieving dendrite-free alkali metal batteries. Common strategies, e.g. expanding the interlayer spacing of anode materials, can enhance bulk diffusion of Li, but are less efficient for Na and K due to their larger ionic radius. Herein, we propose a universal strategy to drastically improve the mass transport efficiency of Na/K by introducing open mesochannels in carbon hosts. Such pore engineering can increase the accessible surface area by one order of magnitude, thus remarkably accelerating the surface diffusion, as visualized by in-situ transmission electron microscopy. In particular, once the mesochannels are filled by Na/K metals, they become the superfast channels for mass transport via the mechanism of interfacial diffusion. Thus-modified carbon hosts enable Na/K filling in their inner cavities and uniform deposition across the whole electrodes with fast kinetics. The resulting Na metal anodes can exhibit stable dendrite-free cycling with outstanding rate performance at high current density up to 30 mA cm -2 . This work presents an inspiring attempt to address the sluggish transport issue of Na/K, as well as valuable insights into the mass transport mechanism in porous anodes for high-performance alkali metal storage. This article is protected by copyright. All rights reserved.