Sodium Tetrakis(hexafluoroisopropyloxy)aluminates: Synthesis and Electrochemical Characterisation of a Room‐Temperature Solvated Ionic Liquid

Weakly coordinating anions (WCAs) are used throughout chemistry to minimise cation-anion interactions in the solid and solution states. The ability to suppress ion-pairing has important bearings - or impacts on the properties of materials, on singlesite catalysis and on ionic conductivity. Fluorinated alkoxy aluminates (containing [Al(ORF)(4)](-) anions) are an attractive class of WCA owing to their high thermodynamic stability, stemming from strong aluminium-oxygen bonds, and the ability to tailor their steric and electronic properties by changing the organic substituents (R). This work explores the structural and electro- chemical properties of sodium tetrakis(hexafluoroisopropyloxy)aluminate, Na[Al(hfip)(4)] center dot xDME (hfip= hexafluoroisopropyloxy, (OPrF)-Pr-i, DME= 1,2-dimethoxyethane, x= 3 or 1). When solvated with one DME molecule, Na[Al(hfip)(4)] center dot DME is a room-temperature solvated ionic liquid, with an activation energy of conduction of 0.4 eV. Both Na[Al(hfip)(4)] center dot 3DME and Na[Al(hfip)4] center dot DME have been studied as electrolyte salts for sodium-ion batteries, where sodium-ion cycling proceeds but with low capacity retention.