Ion-Docking Effect Enabling Rechargeable High-Voltage Magnesium-Iodine/Chlorine Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable magnesium (Mg) batteries are attractive for energy storage due to low cost and resistance to dendrite formation.
• Current limitations include a narrow selection of cathode materials, resulting in low voltage and capacity.

Purpose of the Study:

• To develop a high-energy and high-power density magnesium battery system.
• To activate the cathodic activity of halogens for improved battery performance.

Main Methods:

• Exploiting the ion-docking effect between iodine cations (I+) and chlorine anions (Cl-) in a magnesium-iodine/chlorine (Mg-I/Cl) battery prototype.
• Investigating the role of halogen species' solvation state on redox reactions.

Main Results:

• A Mg-I/Cl battery prototype achieved a high discharge plateau of 3.0 V and capacity over 400 mAh g-1.
• Demonstrated stable cycling for 500 cycles, ultra-fast charging at 20C, and low-temperature performance at -30 °C.

Conclusions:

• The ion-docking effect successfully facilitates multi-electron redox reactions of halogens.
• This Mg-I/Cl battery design offers a promising pathway for developing high-energy-density Mg battery systems.