Flexible Titanium Nitride‐Based Membrane Reactor for S8/Li2S and Dendrite Regulation in Lithium‐Sulfur Batteries

Abstract Simultaneous regulation of S 8 /Li 2 S solid‐liquid redox conversion at the cathode and lithium (Li) dendrite growth at the anode is essential for advancing lithium‐sulfur (Li─S) batteries. Herein, a flexible titanium nitride‐based membrane (TiNOCF) is developed as a membrane reactor (MR) to enhance sulfur redox kinetics, activates S 8 /Li 2 S solid and guide dendrite horizontal growth. The TiNOCF MR at the sulfur cathode side endows the Li─S cell with a remarkable high‐rate capacity of 851.4 mAh g −1 and a stable cycling retention of 94.8% after 200 cycles at 5 C. At the Li anode side, it maintains the Li/Li cell with stable cycling for 2000 h with an ultra‐low overpotential of 38.1 mV at a current density of 2 mA cm −2 . For high sulfur‐loading, TiNOCF MR gives the full cells (10 mg sulfur cm −2 ) with an areal capacity of 10.2 mAh cm −2 at 0.1 C and the pouch cells (9.5 mg sulfur cm −2 ) with 10.9 mAh cm −2 at 36 mA. Mechanism analysis reveals the key roles of titanium (Ti 3+ ) and nitrogen (N 3− ) sites in confinement catalysis and directional dendrite growth, enabling high‐areal capacity, fast‐charging and stable‐cycling features.