Chaotropic Electrolyte Enabling Wide-Temperature Metal-Free Battery.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Metal-free aqueous batteries are promising for grid-scale energy storage due to safety and cost.
• Challenges include electrolyte instability and electrode limitations.
• Ammonium-ion (NH4+) diffusion kinetics offer an alternative to metal-based systems.

Purpose of the Study:

• To develop a stable and high-performance metal-free aqueous battery.
• To investigate the role of electrolyte modulation in battery performance.
• To explore ammonium-iodine chemistry for energy storage applications.

Main Methods:

• Assembly of an aqueous ammonium-iodine battery using a chaotropic electrolyte, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) anode, and iodine composite (I2@CC) cathode.
• Experimental investigations including electrochemical performance testing at various temperatures.
• Theoretical calculations to understand electrolyte-electrode interactions and ion transport mechanisms.

Main Results:

• The chaotropic electrolyte enhances stability by modulating hydrogen bonding and forming a hydrophobic cationic sieve (HCS) on the anode.
• The chloride-containing electrolyte facilitates the I+/I0 redox reaction at the cathode via [ICl]1- interhalogen formation.
• The assembled aqueous ammonium-iodine batteries (AIBs) demonstrate superior electrochemical performance at room temperature and -20 °C.

Conclusions:

• Electrolyte modulation is a strategic approach for developing stable and efficient metal-free aqueous batteries.
• The proposed ammonium-iodine battery system shows significant potential for grid-scale energy storage.
• The findings provide insights into overcoming limitations of current metal-free battery technologies.