Sodium sulfur batteries have an excellent cost/performance ratio, which makes them interesting candidates for electric vehicles and for stationary grid storage solutions. However, their application has been limited due to high operating temperatures over 300 °C and the need to manage soluble discharge products that form during cycling.
Cary Pint, Vanderbilt University, Nashville, USA, and colleagues found a way to mitigate the loss of soluble intermediate discharge products by confining the sulfur in a microporous carbon matrix. The carbon material was obtained by dehydrating table sugar in sulfuric acid, followed by pyrolysis at high temperature. After sulfur was infiltrated into the carbon material, a battery was assembled using a dimethoxyethane (glyme)-based electrolyte and sodium metal as the anode.
The resulting sodium sulfur battery operates at room temperature and showed high capacity (> 300 mAh/gS) over 1500 cycles at a rate of 1 C. The researchers emphasize the simplicity of their method along with the excellent performance and low cost of the materials. Together, this could make the approach suitable for grid storage and as a cheap alternative to lithium-ion batteries.
- A Sugar-Derived Room-Temperature Sodium Sulfur Battery with Long Term Cycling Stability,
Rachel Carter, Landon Oakes, Anna Douglas, Nitin Muralidharan, Adam P. Cohn, Cary L. Pint,
Nano Lett. 2017.