Electrolytes for magnesium-ion batteries

Abstract

Disclosed is a class of organic salts and electrolytes, generally for use with electrochemical devices. Some of these salts enable the transport of magnesium ions without the presence of any additives, such as halide ions. Precursors are generated using simple fluorinated alcohols as well as abundant reagents. These precursors, often dissolved in ethereal solvents, may be combined with an appropriate Lewis acid to result in solutions that are able to conduct ions and allow for reversible electrodeposition.

What is claimed is: 
     
         1 . A composition of matter, represented by the formula M(OR) 2 , wherein R is represented by the formula CR 1 R 2 R 3  and R 1 , R 2 , and R 3  independently represent a hydrogen atom, a halogen atom, or a substituted or non-substituted hydrocarbyl, haloalkyl or haloaryl group;
 wherein M is an alkaline earth metal; and   wherein R is comprised of at least one hydrogen atom and at least one halogen atom.   
     
     
         2 . The composition of matter of  claim 1 , wherein the haloalkyl or haloaryl groups are fluoroalkyl or fluoroaryl groups. 
     
     
         3 . The composition of matter of  claim 2 , wherein R is a C 1 -C 11  fluoroalkyl or fluoroaryl that is unsubstituted, or alternatively, substituted with one or more heteroatom linkers. 
     
     
         4 . The composition of matter of  claim 3 , wherein R is a trifluoroethyl, hexafluoro-iso-propyl, or hexafluoro-2-phenyl-2-propyl group and derivatives thereof. 
     
     
         5 . The composition of matter of  claim 1 , wherein M is Mg. 
     
     
         6 . A composition of matter substantially represented by the formula M1 (M2R′ n R″ m ) 2 , wherein n+m=4, M1 comprises an alkaline earth metal, M2 comprises a Group III metal, and R′ and R″ are independently fluorinated or non-fluorinated moieties. 
     
     
         7 . The composition of matter of  claim 6 , wherein R′ and R″ are independently selected from the group consisting of alkyl, fluoroalkyl, alkoxy, fluoroalkoxy, hexamethyldisilazane, or his (trifluoromethane)sulfonimide. 
     
     
         8 . The composition of matter of  claim 6 , wherein M1 is Mg and M2 is Al. 
     
     
         9 . The composition of matter of  claim 8 , wherein R′ and R″ are equivalent moieties. 
     
     
         10 . An electrolyte precursor represented by the formula MgR 2 , wherein R is a halogenated alkoxide. 
     
     
         11 . The composition of matter of  claim 10 , wherein the halogenated alkoxide is a fluorinated alkoxide. 
     
     
         12 . The electrolyte precursor of  claim 11 , wherein the fluorinated alkoxide is trifluoroethoxide, hexafluoro-iso-propoxide, or hexafluoro-2-phenyl-2-propoxide. 
     
     
         13 . The composition of matter of  claim 10 , wherein the halogenated alkoxide is substantially represented by the formula M2R′ n R″ m , wherein n+m=4, M2 comprises a Group III metal, and R′ and R″ are independently fluorinated or non-fluorinated moieties. 
     
     
         14 . An electrochemical device, comprising:
 an anode;   a cathode; and   an electrolyte solution,   wherein the electrolyte solution comprises an electrolyte precursor of  claim 10 .   
     
     
         15 . A method for generating a precursor, comprising at least one of the following steps:
 combining a first material, comprising at least one of a magnesium dialkoxide, magnesium diaryloxide, magnesium metal, magnesium alloy, Mg(OH) 2 , MgH 2 , or any dialkyl magnesium species with a second material, comprising a halohydrin or a fluorinated alcohol;   combining an alkaline earth metal species with a Group III metal species in a manner substantially represented by the chemical equation: M1R′ 2 +2M2R″ 3 →M1(M2R′ n R″ m ) 2 , wherein n+m=4, M1 comprises an alkaline earth metal, M2 comprises a Group III metal, and R′ and R″ are independently fluorinated or non-fluorinated moieties; or   combining an alkaline earth metal species with a Group III metal species in a manner substantially represented by the chemical equation: 2M3M2R 4 +M1X 2 →M1(M 2 R 4 ) 2 +2M3X, wherein X is a halogen, M1 comprises an alkaline earth metal, M2 comprises a Group III metal, M3 is an alkali metal, and R is a fluorinated or non-fluorinated moiety.   
     
     
         16 . The method of  claim 15 , wherein generating the precursor occurs in the presence of an ethereal solvent. 
     
     
         17 . The method of  claim 16 , wherein the ethereal solvent is comprised of at least one of the group of tetrahydrofuran, dimethoxyethane, and higher order glymes, such as triglyme or tetraglyme. 
     
     
         18 . The method of  claim 15 , further comprising recovering at least some alcohol resulting from the generation of the precursor. 
     
     
         19 . The method of  claim 15 , wherein the magnesium dialkoxide is magnesium methoxide, magnesium ethoxide, magnesium isopropoxide, or magnesium tert-butoxide. 
     
     
         20 . The method of  claim 15 , wherein the halohydrin is trifluoroethanol, hexafluoro-iso-propanol, or hexafluoro-2-phenyl-2-propanol. 
     
     
         21 . A method for generating an electroactive electrolyte, comprising generating a precursor by the method of  claim 15 , then further reacting the precursor with a secondary component. 
     
     
         22 . A solvated electroactive electrolyte, comprising:
 a solvated cation species, represented by the formula MgR 2 , wherein R is a fluorinated or non-fluorinated moiety;   an anion; and   an ethereal solvent.   
     
     
         23 . The solvated electroactive electrolyte of  claim 22 , wherein the anion comprises a species represented by the formula AlR′ 3 , wherein R′ is a fluorinated or non-fluorinated moiety. 
     
     
         24 . The solvated electroactive electrolyte of  claim 23 , further comprising a solid polycyclic aromatic hydrocarbon. 
     
     
         25 . The solvated electroactive electrolyte of  claim 24 , wherein the solid polycyclic aromatic hydrocarbon is anthracene. 
     
     
         26 . An electrochemical device, comprising:
 an anode;   a cathode; and   an electrolyte solution,   wherein the electrolyte solution comprises a solvated electroactive electrolyte of  claim 22 .   
     
     
         27 . The electrochemical device of  claim 26 , wherein the device is further configured to operate as a battery. 
     
     
         28 . The electrochemical device of  claim 27 , wherein the cathode comprises at least one of elemental sulfur; a sulfur compound; a Chevrel-phase compound; a conversion type or an intercalation type compound. 
     
     
         29 . The electrochemical device of  claim 27 , wherein the plating coulombic efficiency after 50 cycles exceeds 90%. 
     
     
         30 . The electrochemical device of  claim 27 , wherein the plating coulombic efficiency after 100 cycles exceeds 95%. 
     
     
         31 . The electrochemical device of  claim 27 , wherein the conductivity of the device electrolyte ranges from about 3 mS/cm to about 10 mS/cm. 
     
     
         32 . The electrochemical device of  claim 27 , wherein the oxidative stability of the electrolyte solution ranges from about 2.5 V to about 3.5 V on a Pt electrode and 3.5 V to about 5.0 V on an Al electrode. 
     
     
         33 . An electrochemical device, comprising:
 an anode;   a cathode; and   an electrolyte solution,   wherein the electrolyte solution comprises a compound represented by the formula MR, wherein R is a halogenated alkoxide and M is an alkali metal.   
     
     
         34 . A method of improving or stabilizing the performance of an electrochemical device, comprising the steps of:
 providing an electrolyte solution;   providing a quantity of anthracene; and   combining the electrolyte solution with the anthracene.