On the Practical Applications of the Magnesium Fluorinated Alkoxyaluminate Electrolyte in Mg Battery Cells

Abstract

High-performance electrolytes are at the heart of magnesium battery development. Long-term stability along with the low potential difference between plating and stripping processes are needed to consider them for next-generation battery devices. Within this work, we perform an in-depth characterization of the novel Mg[Al(hfip) 4 ] 2 salt in different glyme-based electrolytes. Specific importance is given to the influence of water content and the role of additives in the electrolyte. Mg[Al(hfip) 4 ] 2 -based electrolytes exemplify high tolerance to water presence and the beneficial effect of additives under aggravated cycling conditions. Finally, electrolyte compatibility is tested with three different types of Mg cathodes, spanning different types of electrochemical mechanisms (Chevrel phase, organic cathode, sulfur). Benchmarking with an electrolyte containing a state-of-the-art Mg[B(hfip) 4 ] 2 salt exemplifies an improved performance of electrolytes comprising the Mg[Al(hfip) 4 ] 2 salt and establishes Mg[Al(hfip) 4 ] 2 as a new standard salt for the future Mg battery research.

Solvent Molecule Design Enables Excellent Charge Transfer Kinetics for a Magnesium Metal Anode

“…Owing to lacking effective SEI layers, an important current electrolyte research consensus is to develop reductively stable electrolytes which are less liable to react with the Mg electrode in thermodynamics, such as reduction-resistant salts dissolved in ether-based solvent, and thus the exposed fresh Mg surface can support reversible Mg plating/stripping. − Although considerable advances have been accomplished in recent two decades, − these new-type electrolytes still suffer from many intractable problems, such as a complex synthesis process, high cost, and Cl – corrosion. Especially, they nearly all have the disadvantage of the high sensitivity to water content, which could be not suitable for practical commercial application.…”

Battery Performance Amelioration by Introducing a Conducive Mixed Electrolyte in Rechargeable Mg–O2 Batteries

“…Each of the Mg 2p XPS spectra could be deconvoluted into two peaks. The lower-binding-energy peak (centered around 50.8 eV) could be correlated to MgO, while the other peak might be assigned to Mg­(OH) 2 . − Post-maximum recharge FESEM micrographs of the cathodes are given in Figure f,g, in which the structural morphology of the discharge products can be seen. The CSE-based Ru/CNT maximum-recharge cathode (i.e., recharged after the full discharge) in Figure f shows the leaflike morphology of the accumulated products on it, which could be associated with undecomposed MgO formed on the cathode.…”

Is One of the Least Coordinating Anions Suitable to Serve as Electrolyte Salt for Magnesium‐Ion Batteries?

“…To our knowledge, this important field of research is still in its infancies. [22,24,40] Deposition Number(s) 2193348 (for [Mg(DME) 3 ][Al(OR F ) 4 ] 2 ) contain(s) the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service.…”

“…The hfip electrolyts have been further investigated and other WCA-electrolytes have been developed and tested. [22,23,24] We note that these borate and aluminate WCAs originate from Strauss's [25] and our group [12,26,27] and have been extensively used in diverse fields, i. e., for reactive cations [28] and ionic liquids, [15] but also battery electrolyte work. [13,29,30] The most chemically robust and least coordinating WCA of this entire WCA class is the one in which the remaining β-H atoms in the hfip-residue are replaced by CF 3 groups to form the [Al(OR F ) 4 ] À anion (R F = C(CF 3 ) 3 ).…”