Magnesiothermically Synthesized TiO-Decorated 3D N-Doped Graphitized Porous Carbon as a Multifunctional Sulfur Host for Li-S Batteries

Abstract

Lithium-sulfur batteries are promising next-generation energy storage platforms due to their high theoretical energy density, cost-effectiveness, and environmental benefits. However, challenges such as the lithium polysulfide (LiPS) shuttling effect, low Coulombic efficiency (CE), and poor sulfur conductivity hinder their practical application. To address these challenges, we designed a previously unreported sulfur (S) host material, titanium monoxide-decorated 3D N-doped graphitized porous carbon (TiO-NGPC), via a simple and efficient magnesium thermal reduction method. TiO nanoparticles embedded in N-doped graphitized porous carbon act as polar anchors for soluble LiPSs, accelerating redox reactions and alleviating the shuttle phenomenon. Simultaneously, the 3D graphitized carbon structure facilitates efficient electron transport. These synergistic effects collectively contribute to improved sulfur utilization. When employed as a sulfur-loaded cathode material, TiO-NGPC/S delivers an initial specific capacity of 1082.32 mAh g-1 at 1.0 C, retaining 580.68 mAh g-1 after 1000 cycles with a CE of 96.06%, demonstrating excellent cycling stability. At a high sulfur loading of 8.97 mg cm-2, it achieves a specific capacity of 1100.36 mAh g-1 and an area-specific capacity of 9.87 mAh cm-2. Furthermore, the assembled pouch cell exhibited an outstanding electrochemical performance, delivering a high specific capacity of 1158.78 mAh g-1 with a corresponding CE of 99% during the first discharge cycle. Density functional theory simulations confirm the strong adsorption of LiPSs and catalytic activity of TiO, highlighting its potential as a multifunctional host for high-performance lithium-sulfur batteries.