MoS2-modified graphite felt as a high performance electrode material for zinc–polyiodide redox flow batteries

Abstract

Zinc–polyiodide redox flow battery (RFB) systems with highly soluble triiodide/iodide (I₃⁻/I⁻) couples have demonstrated significantly enhanced energy densities. However, their low power density has limited their broad application. In this work, MoS₂ nanoplates were in situ grafted onto graphite felt (GF) surfaces to accelerate the I₃⁻/I⁻ redox reaction. The hexagonal phase MoS₂ with enlarged interlayer spacing can facilitate the diffusion of the electrolyte, and the defects on the MoS₂ nanoplates can serve as very effective catalytic active sites. Cyclic voltammetry testing revealed the high catalytic performance of MoS₂ in the I₃⁻/I⁻ redox reaction. A non-flow cell with the MoS₂-modified GF serving as a positive electrode showed a higher energy efficiency than that of pristine GF; increases of about 10.2% and 10.9% at current densities of 30 mA cm⁻² and 40 mA cm⁻² were obtained with the optimized electrode, respectively.