Flexible Electrocatalytic Nanofiber Membrane Reactor for Lithium/Sulfur Conversion Chemistry

Severe lithium polysulfide (LiPS) shuttle effects and sluggish electrochemical conversion kinetics constitute bottlenecks in developing fast-rechargeable, high-energy, and high-power Li/S batteries. Here, a flexible and conductive TiN-Ti4O7 core-shell nanofiber (TiNOC) membrane reactor is designed to electrocatalytically mediate Li/S conversion chemistry. The Ti, N, and O atoms in the nanofiber function as electrocatalysts and chemical confinement active sites to initiate long-chain LiPS conversion and phase change, as well as to suppress soluble LiPS shuttling. With a sulfur cathode-membrane reactor module configuration, Li/S cells possess a high sulfur utilization of 91.20%, good rate capability of 869.10 mA h g(-1), and high capacity retention of 92.49%, with a coulomb efficiency of 99.57% after 200 cycles at 5 C. Density functional theory (DFT) calculations revealed that the optimized chemisorption configurations facilitate the elongation of Li-S and S-S bonds, as well as charge transfer along Ti-S and Li-N bonds, which favors bond breakage, bond formation, and the activation of solid-state S-8, Li2S2, and Li2S. Layer-by-layer module stacking provides Li/S batteries with a high areal sulfur loading of 12.00 mg cm(-2) to deliver a high areal capacity of 14.40 mA h cm(-2) at 2.26 mA. Two batteries in series can power real-world applications such as light emitting diode (LED) bulbs with a high energy output of 69.00 mW h.