Effect of an imidazole-based ionic liquid as anti-corrosion additive on the performance of Al-air batteries

Abstract

Al-air batteries (AABs) have been regarded as a promising new energy source. However, the self-corrosion of Al anode leads to a loss of battery capacity and a decrease in battery life, limiting its commercial applications. Herein, we introduced an imidazole-based ionic liquid, namely, 1-hexadecyl-3-methylimidazolium hexafluorophosphate (HMIH), as electrolyte additive for alkaline AABs. The inhibition effect was evaluated by hydrogen evolution experiment, electrochemical tests, surface analysis, and theoretical calculations. The findings show that the AABs with this HMIM-containing electrolyte demonstrated well-suppressed self-corrosion and enhanced electrochemical performance. HMIH appears to reside at the interface and suppress the detrimental side reactions. After adding 4 mM HMIH, the Al anode’s utilization increased from 34.7% to 71.4%, the specific capacity density increased from 1034 mAh g−1 to 2128 mAh g−1, and the energy density increased from 1220 Wh kg−1 to 2554 Wh kg−1, which is helpful in reducing the waste of Al resources. This work provides a promising modulation strategy for high-performing Al anodes and can greatly promote the commercial development of AABs.