The Polymeric Sulfur Hosts From Ferrocene-Based Metal-Organic Framework@Ti3C2 Array Structure for Upgrading Energy Density and Longevity of Lithium-Sulfur Batteries

Abstract

Polymeric sulfur is emerging as a cathode active material for lithium-sulfur (Li─S) batteries, which can effectively inhibit polysulfide shuttling through the formation of C─S covalent bonds. However, low conductivity and poor electrocatalytic activity of polymeric sulfur severely counteract the electrochemical performance, especially for high-sulfur-loading cathodes. Herein, it is presented one type of new polymeric sulfur host materials composed of ferrocene-based nickel metal-organic framework (NiFc) loaded on the surface of Ti₃C₂ nanosheets (Ti₃C₂@NiFc), which is prepared through inverse vulcanization reaction between NiFc and sulfur element. The sulfur copolymers significantly accelerate the redox kinetics and effectively inhibit polysulfide shuttling during cycling. The resultant electrode delivers a high gravimetric capacity of 1162 mAh g⁻¹, the areal capacity of 8.37 mAh cm⁻² and a volumetric capacity of 1146 mAh cm⁻³ at 0.2 C. The electrochemical performance can rival the reported state-of-the-art those in Li-S batteries. This work provides new protocols for the development of polymeric sulfur cathode materials to achieve high energy density and long life of Li-S batteries.