Towards High-Performance Aqueous Zn-Organic Batteries via Using I^--Based Active Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Organic cathodes offer structural diversity and fast kinetics for aqueous zinc batteries.
• Existing organic cathodes suffer from low average working voltage, limiting energy density.

Purpose of the Study:

• To develop a high-performance organic cathode for aqueous zinc batteries.
• To enhance energy density and voltage by combining ion storage and redox conversion.

Main Methods:

• Utilized a diquinoxalino[2,3-a:2',3'-c]phenazine (HATN)@CMK-3 composite as the cathode material.
• Introduced an iodide-based active additive into a 0.5 M Zn(OTf)2 electrolyte.
• Employed in situ/ex situ analyses and computational studies to understand reaction mechanisms.

Main Results:

• The HATN@CMK-3 cathode facilitated co-storage of Zn2+ and H+ ions at low potentials.
• The cathode also promoted the I-/I0 conversion reaction at high potentials.
• Achieved a high average voltage of 0.75 V, long cycle life (10,000 cycles), and high energy density (198 Wh kg-1).

Conclusions:

• The HATN@CMK-3 composite effectively enhances aqueous zinc battery performance.
• The synergistic effect of ion co-storage and redox conversion significantly boosts energy density and stability.
• The developed system shows promise for practical applications, even under demanding conditions like high mass loading and low temperatures.