Chain-Transported Hypercoordinated Chloroaluminate Electrolyte for Solid-State Aluminum-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aluminum-ion batteries (AIBs) offer high safety and environmental benefits but are limited by liquid electrolytes' instability.
• Conventional electrolytes in AIBs exhibit narrow electrochemical stability and interfacial issues, hindering practical application.

Purpose of the Study:

• To develop a novel hypercoordinated chloroaluminate electrolyte (HCCAE) for low-cost, long-life solid-state AIBs.
• To investigate a chain-assisted ion transport mechanism within the solid-state electrolyte.
• To enhance the electrochemical stability and cycling performance of AIBs.

Main Methods:

• Synthesis of a hypercoordinated chloroaluminate electrolyte (HCCAE) using 1-ethyl-3-methylimidazolium chloride (EMIC) and AlCl3.
• Characterization of the electrolyte's ionic conductivity, electrochemical stability window, and electrolyte-electrode interface stability.
• Fabrication and testing of solid-state AIBs utilizing the developed HCCAE.

Main Results:

• The HCCAE demonstrated a high ionic conductivity of 0.89 mS cm-1 and an electrochemical window exceeding 2.6 V.
• Stable aluminum plating/stripping was observed for over 900 hours, indicating excellent electrolyte-electrode compatibility.
• Solid-state AIBs achieved over 2000 cycles with high Coulombic efficiency, showcasing superior cycling performance.

Conclusions:

• The developed HCCAE facilitates a fast and stable solid-state ion conduction pathway, overcoming limitations of traditional electrolytes.
• This research provides crucial insights into ion transport mechanisms in aluminum-based solid electrolytes.
• The findings pave the way for low-cost, high-safety, and long-life solid-state aluminum-ion batteries.