Deeply Rechargeable and Hydrogen-Evolution-Suppressing Zinc Anode in Alkaline Aqueous Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-air batteries offer high theoretical energy density but face challenges with rechargeable zinc anodes.
• Key issues include anode passivation, dissolution, and hydrogen evolution in alkaline electrolytes, limiting battery lifespan and performance.

Purpose of the Study:

• To design and demonstrate a submicron zinc anode that overcomes the limitations of traditional rechargeable zinc anodes in aqueous batteries.
• To improve the cycling stability, discharge capacity, and Coulombic efficiency of zinc anodes by suppressing undesirable side reactions.

Main Methods:

• Development of a submicron zinc anode encapsulated with an ion-sieving coating.
• Utilizing zinc oxide (ZnO) nanorods coated with titanium dioxide (TiO2) as the protective layer.
• Testing the anode's performance in deep cycling conditions with a lean electrolyte.

Main Results:

• The TiO2-coated ZnO nanorod anode effectively suppressed hydrogen evolution and mitigated passivation and dissolution.
• Achieved a high reversible discharge capacity of 616 mAh/g and a Coulombic efficiency of 93.5% at 100% depth of discharge.
• Demonstrated stable deep cycling for approximately 350 cycles in a beaker cell configuration.

Conclusions:

• The ion-sieving coating strategy is effective in enhancing the performance of rechargeable zinc anodes in aqueous electrolytes.
• This design offers a promising pathway for developing stable and high-performance aqueous batteries.
• The underlying design principle may be applicable to other electrode materials in advanced battery systems.