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 S8, 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.