Anion‐Dependent Structure and Properties of Concentrated Aqueous Magnesium Electrolytes
Abstract
Highly concentrated aqueous electrolytes have revitalized the field of aqueous batteries. Herein, we investigated the influence of anions on the physicochemical characteristics, solvation structure, and electrochemical behavior of magnesium aqueous electrolytes. Four salts, featuring acetate, nitrate, perchlorate, and imide anions, were selected to span a wide range of chaotropic and kosmotropic behaviors according to the Hofmeister classification. By combining 1 H, 17 O NMR, and infrared spectroscopy with viscosity measurements, a strong correlation emerges between the anion’s nature and its ability to weaken (chaotropicity) or reinforce (kosmotropicity) the water hydrogen‐bond network. For the nitrate, at the boundary between chaotropic and kosmotropic behavior, and the weakly chaotropic perchlorate, results suggest a uniform solvation around [Mg(H 2 O) x ] 2+ clusters; NO 3 − may retain some interaction with water around Mg 2+ , while ClO 4 − appears more decoupled from Mg 2+ . In contrast, the strongly chaotropic TFSI − (bis(trifluoromethanesulfonyl)imide anion) induces a more pronounced perturbation of the hydrogen‐bond network, with TFSI − largely outside the Mg 2+ hydration shell. Finally, the anion‐dependent solvation contributes to electrochemical performance. A 4 m magnesium perchlorate electrolyte exhibits markedly enhanced capacity retention and Coulombic efficiency than a 4 m magnesium acetate electrolyte. However, the overall electrochemical behavior cannot be described by a simple monotonic relationship with the Hofmeister classification.
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BibTeX
@article{paillot2026aniondependent,
title = {{Anion‐Dependent Structure and Properties of Concentrated Aqueous Magnesium Electrolytes}},
author = {Malaurie Paillot and Alan Wong and Caroline Keller and Carine Mouchaham and Bénédicte Montigny and Pascale Roy and Jean‐blaise Brubach and Sophie Le Caër and Magali Gauthier},
journal = {Batteries \& Supercaps},
year = {2026},
month = oct,
doi = {10.1002/batt.70499},
url = {https://hal.science/hal-05781781v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Anion‐Dependent Structure and Properties of Concentrated Aqueous Magnesium Electrolytes
AU - Malaurie Paillot
AU - Alan Wong
AU - Caroline Keller
AU - Carine Mouchaham
AU - Bénédicte Montigny
AU - Pascale Roy
AU - Jean‐blaise Brubach
AU - Sophie Le Caër
AU - Magali Gauthier
PY - 2026
DA - 2026/10/05
JO - Batteries & Supercaps
DO - 10.1002/batt.70499
UR - https://hal.science/hal-05781781v1
AB - Highly concentrated aqueous electrolytes have revitalized the field of aqueous batteries. Herein, we investigated the influence of anions on the physicochemical characteristics, solvation structure, and electrochemical behavior of magnesium aqueous electrolytes. Four salts, featuring acetate, nitrate, perchlorate, and imide anions, were selected to span a wide range of chaotropic and kosmotropic behaviors according to the Hofmeister classification. By combining 1 H, 17 O NMR, and infrared spectroscopy with viscosity measurements, a strong correlation emerges between the anion’s nature and its ability to weaken (chaotropicity) or reinforce (kosmotropicity) the water hydrogen‐bond network. For the nitrate, at the boundary between chaotropic and kosmotropic behavior, and the weakly chaotropic perchlorate, results suggest a uniform solvation around [Mg(H 2 O) x ] 2+ clusters; NO 3 − may retain some interaction with water around Mg 2+ , while ClO 4 − appears more decoupled from Mg 2+ . In contrast, the strongly chaotropic TFSI − (bis(trifluoromethanesulfonyl)imide anion) induces a more pronounced perturbation of the hydrogen‐bond network, with TFSI − largely outside the Mg 2+ hydration shell. Finally, the anion‐dependent solvation contributes to electrochemical performance. A 4 m magnesium perchlorate electrolyte exhibits markedly enhanced capacity retention and Coulombic efficiency than a 4 m magnesium acetate electrolyte. However, the overall electrochemical behavior cannot be described by a simple monotonic relationship with the Hofmeister classification.
SN - 2566-6223
ER -