Efficient Microwave-Assisted Synthesis of Mxene–Nise2@C Heterostructures for Accelerated Reaction Kinetics of Lithium–Sulfur Batteries

Abstract

To address the severe challenges of sluggish reaction kinetics and shuttle effects in lithium-sulfur (Li–S) batteries, this study ingeniously employed an efficient microwave-assisted strategy to rapidly synthesize the MXene–NiSe2@C (denoted as MA MX–NiSe2@C) heterostructure, serving as a sulfur host material. This method offered key benefits such as rapid and uniform heating, along with high energy efficiency. Theoretical simulations validated that the MXene–NiSe2 heterostructure interface promoted the electron transfer processes, enhanced polysulfides adsorption, catalyzed the multi-step reduction of sulfur, and significantly reduced the energy barrier for Li2S decomposition. Electrochemical experiments demonstrated that MA MX–NiSe2@C notably improved Li–ion diffusion kinetics, accelerated sulfur redox reactions, and effectively mitigated shuttle effects. As a result, Li–S batteries based on the MA MX–NiSe2@C cathode exhibited a high initial capacity of 1222 mA h·g–1 at 0.1 C, enhanced rate performance of 619 mA h·g–1 at 2 C, and remarkable cycling stability. Even after 1000 cycles at a high 2 C rate, the average capacity decay rate per cycle remained at only 0.054%. This efficient synthesis method for MXene–transition metal selenide electrocatalysts, coupled with a thorough investigation of their adsorption and catalytic mechanisms in the intricate multiphase electrochemical reactions of Li–S batteries, provides strong support for the ongoing advancement of Li–S battery technology.

Keywords: Microwave-assisted strategy, Li-S batteries, Heterostructure, MXene, Multiphase electrocatalysis