Year: 2026
Type: preprint
Abstract: The development of practical aluminum-ion batteries requires electrolytes capable of stabilizing multivalent aluminum species while maintaining sufficient ionic conductivity and electrochemical activity. Here, we investigate aluminum trifluoromethanesulfonate (Al(OTf)3) dissolved in propylene carbonate (PC) as a potential halide-free aluminum electrolyte using a combined computational and experimental approach. Density functional theory (DFT) calculations were employed to optimize coordination structures and predict speciation, redox potentials, and vibrational signatures of solvated aluminum complexes. Cyclic voltammetry reveals electrochemical activity with a reduction onset near 0 V versus Al/Al3+, consistent with computational predictions. Fourier-transform infrared spectroscopy indicates significant ionic association between aluminum and triflate anions, suggesting the coexistence of free and coordinated species in solution. Scanning electron microscopy of copper substrates after chronoamperometric deposition shows surface features consistent with metal deposition, while X-ray photoelectron spectroscopy confirms the presence of aluminum-containing species. The electrolyte exhibits an ionic conductivity of approximately 5.4 mS cm-1 at ~0.6 M. These results demonstrate that Al(OTf)3/PC solutions support electrochemical activity of aluminum species but exhibit strong ion association, highlighting key challenges and opportunities for halide-free aluminum battery electrolytes.
Source: ChemRxiv
Author: Bilal Overton
Language: English
Topic: Aqueous and Flow Batteries
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223116990