Sodium sulfur (NaS) batteries are a type of molten salt electrical energy storage device. Currently the third most installed type of energy storage system in the world with a total of 316 MW worldwide, there are an additional 606 MW (or 3636 MWh) worth of projects in planning. They are named for their constituents: Sodium (Na) and Sulfur (S).
Introduction Sodium-sulfur (Na-S) batteries with sodium metal anode and elemental sulfur cathode separated by a solid-state electrolyte (e.g., beta-alumina electrolyte) membrane have been utilized practically in stationary energy storage systems because of the natural abundance and low-cost of sodium and sulfur, and long-cycling stability , .
High-temperature sodium–sulfur (HT Na–S) batteries were first developed for electric vehicle (EV) applications due to their high theoretical volumetric energy density. In 1968, Kummer et al. from Ford Motor Company first released the details of the HT Na–S battery system using a β″-alumina solid electrolyte .
H.S.C. Matseelar, in Renewable and Sustainable Energy Reviews, 2014 Sodium sulfur (NAS) battery is an advanced secondary battery has been pioneered in Japan since 1983 by the Tokyo Electric Power Corporation (TEPCO) and NGK .
Lifetime is claimed to be 15 year or 4500 cycles and the efficiency is around 85%. Sodium sulfur batteries have one of the fastest response times, with a startup speed of 1 ms. The sodium sulfur battery has a high energy density and long cycle life. There are programmes underway to develop lower temperature sodium sulfur batteries.
Among the various battery systems, room-temperature sodium sulfur (RT-Na/S) batteries have been regarded as one of the most promising candidates with excellent performance-to-price ratios.