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

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.