A Highly Reversible Aqueous Sulfur-Dual-Halogen Battery Enabled by a Water-in-Bisalt Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Chlorine-based redox reactions in aqueous rechargeable batteries (ARBs) show promise but face challenges like toxic gas evolution and electrolyte instability.
• Low reversibility and Coulombic efficiency hinder the practical application of chlorine-based ARBs.

Purpose of the Study:

• To develop a stable and efficient aqueous sulfur-dual halogen chemistry for high-performance ARBs.
• To overcome the limitations of traditional chlorine-based ARBs by employing a novel electrolyte and electrode system.

Main Methods:

• Utilized a highly-concentrated water-in-bisalt (WiBS) electrolyte with sulfur anodes and iodine composite electrodes.
• Developed freestanding iodine/carbon cloth cathodes to facilitate continuous I+/I0 reactions and immobilize chlorine species.
• Investigated dual-halogen conversion on the cathode and S/Sx2- redox reactions on the anode.

Main Results:

• Demonstrated successful aqueous sulfur-dual halogen chemistry (ASHBs) with improved stability and efficiency.
• Achieved a high energy density of 304 Wh kg-1 and an average output voltage of 1.32 V.
• Successfully prevented toxic Cl2 gas evolution and electrolyte decomposition through interhalogen formation and immobilization.

Conclusions:

• The developed ASHBs offer a promising low-cost, high-performance alternative for energy storage applications.
• The novel approach using sulfur-dual halogen chemistry in WiBS electrolytes opens new avenues for advanced ARBs.
• This work addresses key limitations in chlorine-based ARBs, paving the way for safer and more efficient battery technologies.