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

The flexible conductive titanium nitride-based nanofiber membrane (TiNOCF), functioning as a membrane reactor (MR) with active sites of chemical confinement catalysis and directional dendrite growth, enhances sulfur redox kinetics, activates the S₈/Li₂S solid and guides lithium (Li) dendrite growth along the membrane interface, enabling high-performance Li─S batteries with excellent high-areal capacity, fast-charging and stable-cycling features.

Abstract

Simultaneous regulation of S₈/Li₂S 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 S₈/Li₂S 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 (Ti³⁺) and nitrogen (N³⁻) sites in confinement catalysis and directional dendrite growth, enabling high-areal capacity, fast-charging and stable-cycling features.