Lithium sulfur (Li-S) batteries are expected to have a great potential. Due to easy availability of cathode material – elemental sulfur – Li-S batteries can be much cheaper than commercial lithium ion batteries that are widely used now. In addition low molecular weight of sulfur and lithium makes Li-S batteries much more energy dense (Scheme 1). This type of batteries is now hot topic in research, that is aimed at solving existing problems, in particular instability of the cathode, resulting in bad cyclability, and formation of soluble polysulfides, that leads to the rapid capacity fading. While IOLITEC can offer carbon materials that could be useful for the cathode construction, our main focus is on the use of ILs as electrolytes for the Li-S batteries.
Scheme 1. Specific energy and voltage of different battery types in comparison to gasoline.
The general advantages that ionic liquids bring as battery electrolytes, which include
- Increased safety due to non-flammability
- Minimized risk of explosion due to ultra-low vapour pressure of ILs
- Wide electrochemical windows
- Comparatively high thermal stability
- High ionic conductivity
- Easy tunability of properties through cation and anion structure modification
But most importantly, ionic liquids can be chosen in a way that minimizes polysulfide solubility and therefore prevents the capacity fading occuring through polysulfide shuttle mechanism.
Due to high potential of Li-S batteries, IOLITEC is currently involved into a few research projects on this topic. If you are interested in application of ILs as electrolytes, please contact us.
Text: Dr. Svetlana Cadu, 2018.