Stabilizing Interface pH by Mixing Electrolytes for High-Performance Aqueous Zn Metal Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc metal batteries are promising for large-scale energy storage.
• Challenges include zinc dendrite growth and side reactions due to unstable interfacial pH and lack of a protective solid electrolyte interphase (SEI).

Purpose of the Study:

• To develop a novel mixed electrolyte strategy to address Zn anode instability in aqueous zinc batteries.
• To improve the lifespan and cycling stability of zinc anodes.

Main Methods:

• A mixed electrolyte system combining 2 M ZnSO4 and 2 M Zn(CF3SO3)2 was employed.
• The strategy focused on interfacial pH buffering and in situ formation of an organic-inorganic SEI layer.

Main Results:

• The mixed electrolyte successfully buffered interfacial pH and induced SEI formation, preventing dendrite growth and side reactions.
• Zinc anodes demonstrated over 400 cycles lifespan enhancement, stable cycling over 270 hours at 62% depth of discharge (DOD), and high Coulombic efficiency (CE) of 99.5% for 1000 cycles at 1 mA cm-2.

Conclusions:

• The proposed mixed electrolyte strategy effectively enhances the performance and stability of aqueous zinc metal batteries.
• This approach offers a promising pathway for developing practical and durable electrolyte systems for zinc-based energy storage applications.