Nanosized Li 2 S‐Loaded Polar Porous Carbon Nanofibers as Self‐Supporting Electrodes in Anode‐Free Lithium–Sulfur Batteries

Abstract Anode‐free lithium–sulfur (Li–S) batteries with Li 2 S as the cathode offer a promising alternative to improve practical energy density but suffer from sluggish redox kinetics on the cathode side and chaotic Li plating/stripping process on the copper current collectors. In this work, phosphorus‐doped porous carbon nanofibers (P‐CNFs) are served both as self‐standing hosts for Li 2 S cathode and 3D current collectors for Li deposition. In the cathode, nanoscale Li 2 S particles (less than 10 nm in size) are in situ synthesized via carbon thermal reduction of lithium sulfate which is confined within the brush layer of anionic spherical polyelectrolyte brushes. The incorporation of Li 2 S nanoparticles within the void of P‐CNFs (Li 2 S@P‐CNFs) imparts unimpeded electron/ion transport at the polar carbon matrix interface, thus enhancing the Li 2 S conversion reaction kinetics and mitigating the shuttling effect of polysulfides during cycling. Moreover, the lithiophilic P‐CNFs skeleton with interconnected macropores effectively homogenizes Li plating behavior, resulting in smooth and compact deposition morphology. As a result, the Li 2 S@P‐CNFs||P‐CNFs full cell delivers a low‐capacity decay of 0.051% cycle −1 for 1000 cycles at 1 C. This work gives a unique strategy for the practicalization of anode‐free Li–S batteries, with the potential to extend to other battery systems.