High and intermediate temperature sodium-sulfur batteries for energy storage: development, challenges and perspectives.

In view of the burgeoning demand for energy storage stemming largely from the growing renewable energy sector, the prospects of high (>300 °C), intermediate (100-200 °C) and room temperature (25-60 °C) battery systems are encouraging. Metal sulfur batteries are an attractive choice since the sulfur cathode is abundant and offers an extremely high theoretical capacity of 1672 mA h g upon complete discharge. Sodium also has high natural abundance and a respectable electrochemical reduction potential (-2.