High-energy non-aqueous lithium sulfur (Li--S) redox flow batteries are of interest for stationary applications. However, the presence of insoluble short-chain polysulfides largely sacrifices the high energy opportunity due to deposition of Li2S2/Li2S-- onto the current collectors (for example, graphite felt). In addition, the unstable interface between the conventional electrolyte and the lithium metal anode surface also limits the long-term cycling performance of the redox flow batteries.
To address these issues, PNNL researchers have developed a device that improves the long-term performance of high-energy lithium sulfur redox flow batteries. The device comprises a lithium sulfur redox flow battery with an electrolyte composition containing a dissolved Li2Sx electroactive salt and a solvent selected from dimethyl sulfoxide, tetrahydrofuran, or a mixture thereof. The device also includes a supporting salt at a concentration of at least 2 Molar that is measured by moles of supporting salt divided by the volume of the solvent without considering the volume change of the electrolyte after dissolving the supporting salt.
- Prevents degradation in lithium sulfur redox flow batteries
- Improves long-term performance of redox flow batteries