Status and Challenges of Cathode Materials for Room-Temperature Sodium-Sulfur Batteries.

Room-temperature sodium-sulfur (RT Na-S) batteries have become the most potential large-scale energy storage systems due to the high theoretical energy density and low cost. However, the severe shuttle effect and the sluggish redox kinetics arising from the sulfur cathode cause enormous challenges for the development of RT Na-S batteries. This review systematically sheds light on the rational design strategies of integrating porous carbon matrix with "adsorption-catalysis" agents, including transition-metal single-atom, transition-metal nanoclusters, transition-metal compounds, or heterostructures. Moreover, the multistep reaction mechanism accompanied with the evolution process of various sodium polysulfides during the redox process is systematically summarized on the basis of electrochemical technique analysis and ex situ/in situ characterization. Finally, the future perspectives and potential research directions are outlined to provide a guideline for the continuous development of RT Na-S batteries.