Energy storage devices having anodes containing Mg and electrolytes utilized therein
For a metal anode in a battery, the capacity fade is a significant consideration. In energy storage devices having an anode that includes Mg, the cycling stability can be improved by an electrolyte having a first salt, a second salt, and an organic solvent. Examples of the organic solvent include diglyme, triglyme, tetraglyme, or a combination thereof. The first salt can have a magnesium cation and be substantially soluble in the organic solvent. The second salt can enhance the solubility of the first salt and can have a magnesium cation or a lithium cation. The first salt, the second salt, or both have a BH 4 anion.
1. An energy storage device comprising an anode comprising Mg and an electrolyte solution, the electrolyte solution comprising:
an organic solvent selected from the group consisting of diglyme, triglyme, tetraglyme, and combinations thereof;
a first salt substantially dissolved in the organic solvent and comprising a magnesium cation; and
a second salt substantially dissolved in the organic solvent and comprising a magnesium cation or a lithium cation;
wherein one of the first salt or the second salt comprises a BH 4 anion and the other of the first salt or the second salt comprises a bis(trifluoromethanesulfonyl)imide (TFSI) anion.
2. The energy storage device of claim 1 , wherein the first salt comprises Mg(BH 4 ) 2 .
3. The energy storage device of claim 1 , wherein the first salt comprises Mg(TFSI) 2 .
4. The energy storage device of claim 1 , wherein the anode has a capacity fade less than 80% within 50 cycles.
5. The energy storage device of claim 1 , wherein the anode has a capacity fade less than 10% within 50 cycles.
6. The energy storage device of claim 1 , wherein the anode has a capacity fade less than 10% within 100 cycles.
7. The energy storage device of claim 1 , wherein the anode has no observable capacity fade within 100 cycles.
8. The energy storage device of claim 1 , wherein the device is a rechargeable energy storage device reversibly plating and stripping Mg.
9. The energy storage device of claim 1 , wherein the second salt is a solubility enhancer for the first salt.
10. A rechargeable energy storage device reversibly plating and stripping Mg, the device comprising:
an anode comprising magnesium; and
an electrolyte solution comprising an organic solvent selected from the group consisting of diglyme, triglyme, tetraglyme, and combinations thereof;
the electrolyte solution further comprising a first substantially dissolved salt comprising Mg(BH 4 ) 2 and a second substantially dissolved salt selected from the group consisting of, LiTFSI, Mg(TFSI) 2 , and combinations thereof;
the energy storage device having less than 10% anode capacity fade within 100 cycles.
11. An electrolyte solution for energy storage devices having an anode comprising magnesium, the electrolyte solution comprises:
an organic solvent comprising diglyme, triglyme, tetraglyme, or combinations thereof;
a first salt substantially soluble in the organic solvent comprising a magnesium cation; and
a second salt substantially soluble in the organic solvent and comprising a magnesium cation or a lithium cation;
wherein one of the first salt or the second salt comprises a BH 4 anion and the other of the first salt or the second salt comprises a bis(trifluoromethanesulfonyl)imide (TFSI) anion.
12. The electrolyte solution of claim 11 , wherein the first salt comprises Mg(BH 4 ) 2 .
13. The electrolyte solution of claim 11 , wherein the first salt comprises Mg(TFSI) 2 .
14. The electrolyte solution of claim 11 , wherein the anode has a capacity fade less than 10% over 100 cycles.
15. The electrolyte solution of claim 11 , wherein the anode has no observable capacity fade within 100 cycles.
16. The electrolyte solution of claim 11 , wherein the second salt is a solubility enhancer for the first salt.