AlCl₄ ^--Deficient Eutectic Electrolytes Enable Reversible Iodine Redox-Amphoteric Conversion for Aluminum Battery...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aluminum (Al) batteries offer safe, low-cost energy storage but require improved cathode materials.
• High-voltage and high-capacity cathodes are crucial for advancing Al battery technology.

Purpose of the Study:

• To develop a high-energy-density cathode for Al batteries using reversible iodine conversion.
• To identify critical electrolyte components for stabilizing the iodine redox process.

Main Methods:

• Investigated reversible iodine redox-amphoteric conversion (I-/I0/I+) in Al batteries.
• Utilized AlCl4--deficient eutectic electrolytes to stabilize the conversion process.
• Employed spectroscopic and theoretical analyses to understand electrolyte limitations.

Main Results:

• Eutectic electrolytes significantly suppressed parasitic Cl2 evolution compared to ionic liquids.
• Achieved a specific capacity of 358 mAh g-1 and energy density of 490 Wh kg-1 with the I2 electrode.
• Demonstrated excellent cycling stability with 83.8% retention over 1000 cycles and high-loading electrodes.

Conclusions:

• AlCl4--deficient eutectic electrolytes are key to stabilizing reversible iodine conversion in Al batteries.
• This work provides a new framework for high-energy-density Al batteries utilizing conversion chemistries.
• The findings open avenues for advancing multivalent energy storage systems.