Emerging Aluminum-Ion Capacitors and Lessons from Battery Chemistry

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aluminum-ion capacitors (AICs) are researched for higher energy density than monovalent-ion supercapacitors.
• Aluminum's properties (trivalent charge, abundance, low cost) make AICs promising for sustainable energy storage.

Purpose of the Study:

• To provide a comprehensive review of AIC fundamental charge-storage mechanisms.
• To summarize recent advances in electrode materials, electrolyte engineering, and device architectures for AICs.
• To address challenges in Al3+ ion transport and solvation for improved AIC performance.

Main Methods:

• Review of fundamental charge-storage mechanisms in AICs.
• Analysis of electrode materials, electrolyte engineering, and device architectures.
• Discussion of strategies like structural design, defect engineering, and interfacial optimization to overcome Al3+ ion challenges.
• Assessment of various electrolyte types (aqueous, ionic-liquid, deep-eutectic, quasi-solid-state) and 2D materials (graphene, MXenes).
• Integration of operando characterization and computational modeling insights.

Main Results:

• AICs demonstrate potential for high energy density due to Al3+ ions.
• Significant progress has been made in developing electrode materials and electrolytes for AICs.
• Strategies for overcoming Al3+ desolvation and transport limitations are being developed.

Conclusions:

• AICs represent a promising avenue for next-generation energy storage beyond conventional supercapacitors.
• Addressing challenges in Al3+ ion kinetics and transport is crucial for high-performance AICs.
• Future research integrating characterization and modeling will guide the development of high-rate, long-life, and flexible AICs.