Angstrom-Scale Confined Ion Sieve and Accelerator for Efficient Aqueous Zinc Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Commercialization of aqueous zinc-metal batteries (AZMBs) is limited by dendrite formation and parasitic reactions at the zinc anode.
• Uncontrolled Zn2+ transport and side reactions with water and anions contribute to AZMB instability.

Purpose of the Study:

• To design an angstrom-scale confined ion sieve and accelerator for selective Zn2+ transport.
• To mitigate water- and anion-induced parasitic reactions at the zinc anode in AZMBs.

Main Methods:

• Fabrication of unilamellar Ti0.87O2 nanosheets with atomic Ti vacancies and controlled interlayer spacing (approx. 3.5 Å).
• Characterization of the nanosheets' ion sieving capabilities for Zn2+ (approx. 1.5 Å) while blocking H2O (approx. 4.0 Å) and SO42- (approx. 5.9 Å).
• Electrochemical testing of the Ti0.87O2@Zn anode and Ti0.87O2@Zn//VO2 pouch cells.

Main Results:

• The Ti0.87O2 nanosheets enabled selective and high-flux Zn2+ transport with excellent Zn/SO42- selectivity.
• The Ti0.87O2@Zn anode demonstrated significantly suppressed dendrite growth and parasitic reactions.
• Stable cycling exceeding 5000 h (1 mA cm-2) and 4000 h (5 mA cm-2) was achieved; pouch cells retained 85.4% capacity after 300 cycles.

Conclusions:

• The angstrom-scale confined ion sieve strategy effectively enhances the reversibility of aqueous zinc metal anodes.
• This interfacial design concept offers a promising approach for developing stable and high-performance AZMBs.
• The findings may inspire rational design of confined ion-transport interphases for other aqueous battery systems.