Sustainable Eutectic Electrolytes for Aluminum-Ion Batteries: Design and Recent Advances

Abstract

Aluminum-ion batteries (AIBs) have emerged as promising candidates for next-generation energy storages, benefiting from abundant aluminum element, high theoretical capacity, low cost, and electrolyte safety and tunability. Despite these advantages, AIBs face critical practical challenges including low ionic conductivity, poor aluminum deposition and dissolution reversibility, severe parasitic reactions and dendrite formation, largely rooted in conventional electrolyte limitations. Eutectic electrolytes (EEs) derived from deep eutectic solvents have gained increasing attention due to unique merits low cost, facile preparation, wide electrochemical stability window (ESW), high thermal and chemical stability and adjustable solvation structure. This mini review systematically summarizes recent research progress of EEs for AIBs, focusing on classification, formation mechanisms, key physicochemical properties and electrochemical performance optimisation. Special emphasis is placed on their roles in regulating Al3+ solvation structure, stabilizing electrode-electrolyte interfaces and suppressing parasitic reactions. Remaining challenges and future research directions are discussed to guide rational design of high-performance AIBs and promote their practical development in energy storage applications.