A Stable and Energy-Dense Polysulfide/Permanganate Flow Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Redox flow batteries (RFBs) are crucial for grid-scale energy storage.
• Practical applications require high-performance, stable, and cost-effective RFB systems.
• Existing RFBs face challenges like sluggish kinetics and electrode instability.

Purpose of the Study:

• To develop a high-performance S/Mn RFB using polysulfides and permanganates.
• To enhance electrode stability and catalytic activity for improved cycling.
• To demonstrate a scalable and cost-effective energy storage solution.

Main Methods:

• Fabrication of NiS/Ni foam anode for polysulfide electrocatalysis.
• Development of graphene-modified carbon felt (G/CF) cathode for enhanced stability.
• Utilized NaMnO4 as the catholyte redox-active molecule due to its high solubility.
• Electrochemical testing of S/Mn RFB cells and a three-cell stack.

Main Results:

• Achieved high energy density of 67.8 Wh L⁻¹.
• Demonstrated long cycling lifetime with a low capacity fade rate of 0.025% h⁻¹.
• Reported low electrolyte cost of $17.31 kWh⁻¹.
• Validated scalability with a three-cell stack showing stable cycling over 100 cycles (226.8 h).

Conclusions:

• The developed S/Mn RFB system offers a promising approach for stable, energy-dense, and cost-effective energy storage.
• The optimized electrodes and electrolyte composition contribute to the system's superior performance.
• This strategy provides a viable candidate for future grid-scale energy storage applications.