Sulphur-impregnated flow cathode to enable high-energy-density lithium flow batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Redox flow batteries are key for grid-scale energy storage.
• Current limitations include low energy density and volumetric capacity.

Purpose of the Study:

• To develop a flow cathode with enhanced volumetric capacity and cycle life.
• To overcome the limitations of existing redox flow battery technologies.

Main Methods:

• Utilized a highly concentrated sulfur-impregnated carbon composite for the flow cathode.
• Conducted pseudo-in situ impedance and microscopy characterizations.
• Evaluated electrochemical and morphological reversibility of sulfur redox reactions.

Main Results:

• Achieved a catholyte volumetric capacity of 294 Ah l(-1).
• Demonstrated long cycle life (>100 cycles) with high coulombic (>90%) and energy (>80%) efficiencies.
• Exceeded volumetric capacity of all-vanadium flow batteries (60 Ah l(-1)) and lithium-polysulfide approaches (50-117 Ah l(-1)).

Conclusions:

• The sulfur-impregnated carbon composite flow cathode offers a viable path to high-energy-density flow batteries.
• Effective interfaces between sulfur and carbon enhance electrochemical performance.
• This approach addresses critical challenges in large-scale electricity storage.