Acid-Alkaline Double Electrolytes for High-Energy Aqueous Proton Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous proton batteries offer safety and cost benefits but are limited by water's narrow electrochemical stability.
• Limited voltage restricts the energy density and overall performance of conventional aqueous energy storage systems.

Purpose of the Study:

• To develop a high-voltage aqueous proton battery by expanding the electrochemical stability window.
• To investigate an innovative acid-alkaline double electrolyte configuration for enhanced energy storage performance.

Main Methods:

• Utilized a high-anodic-limit acidic catholyte (7 M H3PO4) and a low-cathodic-limit alkaline anolyte (6 M KOH) separated by a proton exchange membrane (PEM).
• Employed cobalt-doped Prussian blue (CoCuHCF) as the cathode and benzo[c]cinnoline (BCC) as the anode, validated through theoretical and experimental analysis.
• Characterized battery performance including energy density, power density, and cycling stability.

Main Results:

• Achieved an expanded electrochemical stability window (ESW) of 2.91 V.
• Demonstrated high energy density (329.6 Wh kg−1 at 1 A g−1) and power density (14788.3 W kg−1 at 10 A g−1).
• Exhibited excellent cycling stability with 98.3% capacity retention after 1000 cycles.

Conclusions:

• The acid-alkaline double electrolyte strategy effectively enhances the voltage and performance of aqueous proton batteries.
• This approach provides a viable pathway for advancing safe, high-energy aqueous energy storage solutions.
• The findings offer valuable guidance for the future development of next-generation battery technologies.