Na2S-carbon nanotube fabric electrodes for room-temperature sodium-sulfur batteries.

A unique sodium sulfide (Na2S) cathode is developed, which will allow the use of sodium-free anodes for room-temperature sodium-sulfur (Na-S) batteries. To overcome the "inert" nature of the Na2S, a special cathode structure is developed by spreading the multi-walled carbon nanotube (MWCNT)-wrapped Na2S particles onto MWCNT fabrics. Spectroscopic and electrochemical analyses reveal a series of polysulfide intermediates involved in the charge/discharge of the cell. The Na-S battery prepared in full discharge state with the Na2S/MWCNT cathode provides a remarkable capacity of 500 A h kg(-1) (based on sulfur mass) after 50 cycles.