High concentration electrolyte for magnesium battery having carboranyl magnesium salt in mixed ether solvent

1. An electrochemical device, comprising:

an anode comprising magnesium;

a cathode; and

an electrolyte in contact with the anode and the cathode, the electrolyte comprising:

a carboranyl magnesium salt having a Mg 2+ cation and a carboranyl anion; and

a mixed ether solvent in which the carboranyl magnesium salt is dissolved, the mixed ether solvent having viscosity less than one centipoise (cP), and comprising:

a first ether solvent; and

a second ether solvent that is different from the first ether solvent;

wherein the carboranyl magnesium salt is present at a concentration of at least 0.25 molal;

and wherein the electrolyte has an ionic conductivity greater than 3 mS/cm.

2. The electrochemical device as recited in claim 1 , wherein the carboranyl magnesium salt has a formula selected from the group consisting of:

Mg(CB i H [(i+1)−j−k] X j R k ) 2 ,

Mg(C 2 B (i−1) H (i−j−k) X j R k ) 2 ,

Mg(CB i H [(i+1)−j−k] X j R k )X,

Mg(C 2 B (i−1) H (i−j−k) X j R k )X, or

a combination of at least two of the foregoing, wherein i is an integer within a range of 5 through 11, inclusive; j is an integer within a range of 0 through i inclusive; k is an integer between 0 and i inclusive; each X, independently of each other X, is fluorine, chlorine, bromine, or iodine; and each R, independently of each other R, is an alkyl, aryl, alkoxy, aryloxy, their partially or completely fluorinated analogues, or a moiety combining the aforementioned functionalities.

3. The electrochemical device as recited in claim 1 , wherein an anion of the carboranyl magnesium salt is an icosahedral closo-carboranyl anion.

4. The electrochemical device as recited in claim 1 , wherein the electrolyte is stable at an electrical potential of at least 3.0 V.

5. The electrochemical device as recited in claim 1 , wherein the cathode comprises an organic cathode material.

6. The electrochemical device as recited in claim 1 , wherein the carboranyl magnesium salt is present at a concentration of at least 0.8 molal.

7. The electrochemical device as recited in claim 1 , wherein the first ether solvent is selected from tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME).

8. The electrochemical device as recited in claim 1 , wherein the second ether solvent is selected from DME, bis(2-methoxyethyl) ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme).

9. The electrochemical device as recited in claim 1 , wherein the second ether solvent is selected from bis(2-methoxyethyl) ether (diglyme), triethylene glycol dimethyl ether (triglyme), and tetraethylene glycol dimethyl ether (tetraglyme).

10. The electrochemical device as recited in claim 1 , wherein the carboranyl magnesium salt is Mg(CB 11 H 12 ) 2 and wherein the first ether solvent is THF and second ether solvent is diglyme.

11. The electrochemical device as recited in claim 1 , wherein the carboranyl magnesium salt is Mg(CB 11 H 12 ) 2 and wherein the first ether solvent is DME and second ether solvent is diglyme.

12. The electrochemical device as recited in claim 1 , wherein the carboranyl magnesium salt has a formula selected from the group consisting of:

Mg(CB i H [(i+1)−j−k] X j R k ) 2 ,

Mg(C 2 B (i−1) H (i−j−k) X j R k ) 2 ,

Mg(CB i H [(i+1)−j−k] X j R k )X,

Mg(C 2 B (i−1) H (i−j−k) X j R k )X, or

a combination of at least two of the foregoing, wherein i is 11; j is 1; k is 0; and X is fluorine, chlorine, bromine, or iodine and each R, independently of each other R, is an alkyl, aryl, alkoxy, aryloxy, their partially or completely fluorinated analogues, or a moiety combining the aforementioned functionalities.

13. A process for preparing an electrochemical device, comprising:

contacting an anode and a cathode with an electrolyte comprising:

a carboranyl magnesium salt present at a concentration of at least 0.25 molal and having a Mg′ cation and a carboranyl anion; and

a mixed ether solvent having viscosity less than one centipoise (cP) in which the carboranyl magnesium salt is dissolved, the mixed ether solvent comprising:

a first ether solvent; and

a second ether solvent that is different from the first ether solvent.

14. The process as recited in claim 13 , wherein the carboranyl magnesium salt has a formula selected from the group consisting of:

Mg(CB i H [(i+1)−j−k] X j R k ) 2 ,

Mg(C 2 B (i−1) H (i−j−k) X j R k ) 2 ,

Mg(CB i H [(i+1)−j−k] X j R k )X,

Mg(C 2 B (i−1) H (i−j−k) X j R k )X, or

a combination of at least two of the foregoing, wherein i is an integer within a range of 5 through 11, inclusive; j is an integer within a range of 0 through i inclusive; k is an integer between 0 and i inclusive; each X, independently of each other X, is fluorine, chlorine, bromine, or iodine; and each R, independently of each other R, is an alkyl, aryl, alkoxy, aryloxy, their partially or completely fluorinated analogues, or a moiety combining the aforementioned functionalities.

15. The process as recited in claim 13 , wherein the carboranyl magnesium salt comprises an icosahedral closo-carhoranyl anion.

16. The process as recited in claim 13 , wherein the electrolyte is stable at an electrical potential of at least 3.0 V.