Zwitterionic Electrolyte Additives Empowered Robust Zn-I₂ Batteries Enduring a Low Temperature of -40 °C

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Zinc-iodine (Zn-I2) batteries suffer from poor cycling stability due to polyiodide shuttling and zinc anode corrosion.
• Active material loss and anode degradation limit the practical application of Zn-I2 batteries.

Purpose of the Study:

• To develop a bifunctional additive, zwitterionic pyrrole (ZiPy), to mitigate polyiodide shuttling and stabilize the zinc anode in Zn-I2 batteries.
• To investigate the mechanisms by which ZiPy improves battery performance through experimental and theoretical analysis.

Main Methods:

• Design and synthesis of zwitterionic pyrrole (ZiPy) as an electrolyte additive.
• Electrochemical testing of Zn-I2 batteries with and without ZiPy, including long-term cycling and low-temperature performance evaluation.
• Computational modeling and theoretical calculations to understand the interfacial interactions and ion transport.

Main Results:

• ZiPy effectively adsorbs polyiodides and stabilizes the zinc anode interface.
• Incorporation of ZiPy regulates interfacial pH, modifies Zn2+ solvation structure, and promotes (002) plane preferential growth of zinc.
• Batteries with ZiPy achieved remarkable cycling stability, completing 45,000 cycles at 8 A g-1 with 90.1% capacity retention at -40 °C.

Conclusions:

• Zwitterionic electrolyte engineering with ZiPy is a promising strategy for developing high-performance and stable Zn-I2 batteries.
• ZiPy addresses key degradation mechanisms, paving the way for advanced zinc-based energy storage systems.
• The study highlights the potential of tailored molecular design in overcoming limitations in battery technology.