Toward Practical Aluminum Organic Batteries Featuring Covalent Organic Framework

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aluminum metal-organic batteries offer sustainability and high energy density but often lack rigorous performance assessment.
• Previous studies frequently highlight high capacity and power at extreme cycling rates, potentially overlooking long-term stability.
• Covalent organic frameworks (COFs) are emerging as promising electrode materials for next-generation batteries.

Purpose of the Study:

• To rigorously reassess the feasibility of a specific COF, DAAQ-TFP-COF, for rechargeable aluminum batteries.
• To investigate the impact of voltage windows on electrochemical performance and identify optimal operating conditions.
• To elucidate the charge storage mechanism and evaluate electrolyte compatibility for practical applications.

Main Methods:

• Electrochemical testing across various voltage windows using an ionic liquid electrolyte.
• Surface- and bulk-sensitive characterization techniques, including energy-dispersive X-ray spectroscopy and X-ray Raman spectroscopy.
• Evaluation of COF performance in cost-effective amide-based aluminum electrolytes.

Main Results:

• An optimal voltage window (0.5 to 2.0 V) was identified, yielding a capacity of 113.9 mAh g^-1 at 50 mA g^-1 for DAAQ-TFP-COF.
• Characterization confirmed monovalent AlCl₂⁺ as the primary coordination species during charge storage.
• The COF demonstrated stable performance and high Coulombic efficiency in a butyramide-based electrolyte.

Conclusions:

• DAAQ-TFP-COF shows potential for stable rechargeable aluminum batteries when operated within an optimized voltage window.
• Understanding the coordination species and electrolyte compatibility is crucial for advancing COF-based aluminum batteries.
• Further research is needed to address key challenges for the practical implementation of COF electrodes in aluminum batteries.