Anode-free Li–S cells are realized by coupling nano-Li2S embedded in P-doped porous carbon nanofibers (Li2S@P-CNFs) with lithium-free P-CNF current collectors. Polar P-CNFs accelerate Li2S conversion and suppress shuttling, while their lithiophilic, macroporous network homogenizes Li plating for dendrite-free deposits. The full cell sustains 1000 cycles at 1 C with only 0.051% capacity fade per cycle.
Abstract
Anode-free lithium–sulfur (Li–S) batteries with Li2S 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 Li2S cathode and 3D current collectors for Li deposition. In the cathode, nanoscale Li2S 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 Li2S nanoparticles within the void of P-CNFs (Li2S@P-CNFs) imparts unimpeded electron/ion transport at the polar carbon matrix interface, thus enhancing the Li2S 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 Li2S@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.
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