A major breakthrough in the research of sodium sulfur battery has been made by a team of Pakistani and Chinese researchers. Their results on “Sulfur encapsulation into yolk-shell Fe₂N@nitrogen doped carbon for ambient-temperature sodium-sulfur battery cathode” were published in the international renowned journal “Chemical Engineering Journal”.

Aslam et al. successfully synthesized hollow YS-Fe₂N@NC sulfur host material, which can capture soluble polysulfides and accelerate electrochemical reaction. The host material has a unique oval yolk shell structure. Its hierarchical structure and sufficient internal space can accommodate the polysulfides generated in the battery reaction process, and alleviate the volume expansion caused by sodium ion insertion/stripping. In addition, this study provides a systematic method for further understanding the reversible reaction mechanism in the charge/discharge process of sodium sulfur battery. The in/ex-situ experimental results reveal the discharge reaction mechanism of sodium sulfur battery, and confirm that the host material uses its catalytic properties to accelerate the electrochemical reaction, directly convert long-chain polysulfides to short-chain polysulfides without converting into Na₂S₅ and Na₂S₆, thus showing excellent electrochemical performance. The hollow, polar and catalytic material exhibit promising specific capacity of 1123 mAh g^-1 at the rate of 1C for the initial cycle (Fig. 1), good rate capability (845 mAh g^-1 at 2C) and ultra-stable cycling performance with an ultra-low capacity decay of 0.0724% per cycle. The present work highlights the importance of introducing the Fe₂N to catalyse the conversion reactions of polysulfide within NC shell for boosting the RT-Na-S battery in term of high storage capacity, rate capability and stability.