Weakly Solvating Hydrated Eutectic Electrolyte for High-Performance Aluminum-Ion Batteries with Wide Temperature...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous aluminum-ion batteries (AIBs) offer high capacity, safety, and low cost but face challenges like inhomogeneous deposition and corrosion.
• Extreme temperatures and high loads exacerbate stability issues in current AIB electrolytes.

Purpose of the Study:

• To design a stable electrolyte for AIBs that operates effectively across a wide temperature range.
• To address challenges of aluminum deposition, hydrogen evolution, and anode corrosion in AIBs.

Main Methods:

• A hydrated eutectic electrolyte was formulated using Al(ClO4)3·9H2O and methyl carbamate (MC) in a 1:4 molar ratio.
• The electrolyte's structure and its effect on aluminum deposition and solid electrolyte interphase (SEI) formation were investigated.
• Electrochemical performance was evaluated using Al//Al symmetric cells and Al//polyaniline (PANI) full batteries at various temperatures.

Main Results:

• The optimized electrolyte formed a water-deficient, weakly solvated structure ([Al3+(MC)2(H2O)2(ClO4−)2]+) promoting homogeneous aluminum deposition/stripping.
• A dense, anion-rich SEI layer was formed, ensuring long-term anode stability.
• Al//Al cells cycled stably for 600 h at 0.2 mA cm-2; Al//PANI batteries retained 117.7 mAh g-1 after 1100 cycles at 1 A g-1.
• Excellent cycling stability was observed between -15 °C and 50 °C.

Conclusions:

• The developed eutectic electrolyte significantly enhances the stability and cycling performance of aqueous aluminum-ion batteries.
• This electrolyte design offers a viable solution for AIBs operating under demanding conditions and wide temperature fluctuations.
• The findings provide valuable design principles for advancing AIB technology for large-scale energy storage.