High-Power Polysulfide Redox Flow Batteries via an Interfacial Electron Field on a 2D Mesoporous Heterojunction.

Abstract

Due to the high solubility and multielectron transfer capabilities of polysulfides, aqueous polysulfide redox flow batteries (PS-RFBs) have emerged as promising candidates for large-scale energy storage, offering both low cost and high capacity. However, the sluggish electrochemical kinetics of polysulfides leads to significantly high polarization and low energy efficiency. Here, we tailor a two-dimensional ordered mesoporous nitrogen-doped carbon@MoS₂ (Meso-NC@MoS₂) heterojunction with a sandwich-like nanostructure to accelerate the redox kinetics of polysulfides. The in-plane electric field in Meso-NC@MoS₂ optimizes polysulfide adsorption and establishes a directional charge transfer channel, thereby enhancing electron transport from Meso-NC@MoS₂ to S₄^2- and consequently improving the reaction kinetics activity of S₄^2- on the electrocatalyst. As a result, the Meso-NC@MoS₂ based PS-RFBs exhibit a reduction in charging overpotential of approximately 377 mV compared to blank carbon felt, while the battery energy efficiency increases from 42.28% to 85.75% at 20 mA cm^-2. Additionally, the battery can demonstrate a high-power density of 112 mW cm^-2, as well as operating for up to 3200 cycles in 30 days with a high Coulombic efficiency of 99.9% at 60 mA cm^-2.