Dual-Ion Co-Storage via Solvation Structure Tuning Toward Ultrafast and Durable Zinc-Organic Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous Zn-organic batteries offer sustainable and tunable cathode options.
• Challenges include cathode dissolution, degradation, and sluggish kinetics, limiting performance.
• Existing electrolytes struggle to support high-capacity and long-cycling aqueous zinc batteries.

Purpose of the Study:

• To develop an effective electrolyte engineering strategy for high-performance aqueous Zn-organic batteries.
• To investigate the role of potassium chloride (KCl) as a co-solute in ZnCl2 electrolytes.
• To elucidate the mechanism behind enhanced performance in Zn//PTCDA batteries.

Main Methods:

• Electrolyte engineering by adding KCl to ZnCl2 electrolyte.
• Experimental characterization of Zn//PTCDA batteries.
• Molecular dynamics simulations and density functional theory (DFT) calculations.
• Electrochemical performance testing (capacity, rate capability, cycling stability).

Main Results:

• The ZnCl2-KCl electrolyte significantly enhanced electrolyte conductivity and Zn2+ ion diffusion kinetics.
• The Zn//PTCDA battery achieved a capacity of 124.7 mAh g-1 at 0.65 V.
• Exceptional rate performance (56% retention at 30 A g-1) and cycling stability (90.9% after 10,000 cycles) were observed.
• A novel Zn2+/K+ co-storage mechanism in the PTCDA cathode was identified.

Conclusions:

• Electrolyte engineering with KCl is a viable strategy for high-performance aqueous Zn-organic batteries.
• The Zn2+/K+ co-storage mechanism enhances kinetics and stabilizes the cathode structure.
• This work paves the way for durable, high-power metal-organic batteries through rational electrolyte design.