A Fluorinated Alkoxyaluminate Electrolyte for Magnesium-Ion Batteries

Abstract

The lack of electrolytes that simultaneously possess high Coulombic efficiency, conductivity, and voltage stability has hindered the deployment of rechargeable magnesium-ion batteries. With few exceptions, the tenacious oxide layer on magnesium metal has limited the scope of research to halide ion-based electrolytes, which help activate the electrode surface but also limit the working voltage window considerably. Herein, we demonstrate a new class of magnesium electrolytes based on fluoroalkoxyaluminate anions synthesized via a facile and scalable method and its incorporation in a full battery cell. Mixtures of magnesium and aluminum fluoroalkoxides in ethereal solvents result in solutions that can reversibly deposit magnesium metal with near unit efficiency in addition to achieving suitable oxidative stabilities (>3.5 V vs Mg/Mg 2+ on glassy carbon and gold) and conductivities (>6 mS cm −1 ).

A Stable, Non-corrosive Perfluorinated Pinacolatoborate Mg Electrolyte for Rechargeable Mg Batteries

“…Mg and astripping potential at Angewandte Chemie Zuschriften À0.111 V, giving overpotential of 197 mV,w hich is comparable with Mg/MgCl 2 /AlCl 3 (MMAC) electrolytes, [3f] but lower than reported chloride-free Mg electrolytes. Furthermore,t he Mg-FPB electrolyte exhibited an outstanding anodic stability at more than 4.0 Vv s. Mg, which is comparable with reported chloride-free Mg electrolytes, [4][5][6][7] but significantly improved over other reported Mg electrolytes. Furthermore,t he Mg-FPB electrolyte exhibited an outstanding anodic stability at more than 4.0 Vv s. Mg, which is comparable with reported chloride-free Mg electrolytes, [4][5][6][7] but significantly improved over other reported Mg electrolytes.…”

“…[2] However,t he research into rechargeable Mg batteries is still in its infancy, and development of Mg batteries is primarily hampered by two grand challenges,t he lack of high performance Mg 2+ electrolyte [2b,c] and energy-dense cathode materials. [3] The reported Mg 2+ electrolytes applied in Mg batteries are mainly based on the combination of aMg-containing Lewis base (for example,Grignard reagents and MgCl 2 )and aLewis acid (for example,A lCl 3 [4] Mg(CB 11 H 11 F) 2, [5] Mg[Al-(HFIP) 4 ] 2 , [6] and Mg[B(HFIP) 4 ] 2 (HFIP =-OCH(CF 3 ) 2 ). [3] The reported Mg 2+ electrolytes applied in Mg batteries are mainly based on the combination of aMg-containing Lewis base (for example,Grignard reagents and MgCl 2 )and aLewis acid (for example,A lCl 3 [4] Mg(CB 11 H 11 F) 2, [5] Mg[Al-(HFIP) 4 ] 2 , [6] and Mg[B(HFIP) 4 ] 2 (HFIP =-OCH(CF 3 ) 2 ).…”

Magnesium-sulfur battery: its beginning and recent progress

“…[77] Recently, Arnold and co-workers reported that magnesium hexafluoroisopropylaluminate Mg[Al(hfip) 4 ) and conductivities (>6 mS/cm). [78] This conductive salt solution was synthesized via a three-step reaction. Firstly, both educts of magnesium fluoroalkoxide Mg(hfip) 2 and aluminumfluoroalkoxide Al(hfip) 3 need to be synthesized, followed by mixing them in DME.…”

Magnesiumbatterien – ein Aufruf an Synthesechemiker: Elektrolyte und Kathoden dringend gesucht

“…Die oxidative Stabilitätb eträgt 5V gegen Mg (5.7 V gegen Li). [41] Diese Arbeit wurde auf die Synthese von Fluoralkoxyborat-Elektrolyten ausgedehnt, deren Herstellung in einem Schritt durch die Reaktion von Tr is(2H-hexafluorisopropyl)borat und Magnesiumfluorid in 1,2-Dimethoxyethan erfolgte. Die Kristallstruktur des Magnesiumtetraphenylaluminats ((Mg 2 (m-Cl) 3 ·6 THF)(AlPh 4 )), das das Magnesium-Dimer-Kation enthält, wird in Abbildung 2B gezeigt.…”