Ion Pairing and Electrochemical Behavior of Al(OTf)3 in Propylene Carbonate Bilal Overton
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.
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BibTeX
@misc{overton2026pairing,
title = {{Ion Pairing and Electrochemical Behavior of Al(OTf)3 in Propylene Carbonate Bilal Overton}},
author = {Bilal Overton},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010756/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010756/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Ion Pairing and Electrochemical Behavior of Al(OTf)3 in Propylene Carbonate Bilal Overton
AU - Bilal Overton
PY - 2026
DA - 2026/10/21
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010756/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010756/v1
AB - 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.
ER -