Hybrid Electrolytes for Group 2 Cation-based Electrochemical Energy Storage Device

Abstract

This invention relates to the field of energy storage devices, and especially electrochemical energy storage devices including electrolytes comprising an ionic liquid, one or more solvents, and one or more salts of a Group 2 element. Effects on electrochemical performance of the electrolyte of each of the components of the electrolyte were systematically determined. In addition, interactions between the electrolytes and separator films were dissected to optimize electrochemical performance of coin cell batteries.

1 . An electrolytic composition comprising an ionic liquid, one or more solvents, wherein at least one of the one or more solvents is chosen from the group consisting of ethers and nitriles, and a Group 2 salt. 
     
     
         2 .- 4 . (canceled) 
     
     
         5 . An electrolytic composition of  claim 1 , wherein the solvent is a nitrile. 
     
     
         6 . The electrolytic composition of  claim 5 , wherein the solvent is acetonitrile. 
     
     
         7 . The electrolytic composition of  claim 1 , wherein a cationic component of the ionic liquid is piperidinium-based, pyrrolidinium-based, imidazolium-based, or pyridinium-based. 
     
     
         8 . The electrolytic composition of  claim 1 , wherein an anionic component of the ionic liquid is bis(trifluoromethylsulfonyl)imide. 
     
     
         9 . The electrolytic composition of  claim 1 , wherein the ionic liquid is selected from the group consisting of 1-ethyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide, 1-methyl-3-propylimidazoliumbis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazoliumtetrafluoroborate, 1-methyl-3-propylimidazoliumtetrafluoroborate, 1-butyl-3-methylimidazoliumtetrafluoroborate, 1-ethyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-propyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylpyridiniumbis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylpyridiniumtetrafluoroborate, 1-methyl-1-propylpiperidinium-bis(trifluoromethylsulfonyl)imide, 1-butyl-1-methylpiperidinium-bis(trifluoromethylsulfonyl)imide, 1-ethyl-1-methylpyrrolidinium-tetrafluoroborate, 1-methyl-1-propylpyrrolidinium-tetrafluoroborate, 1-butyl-1-methylpyrrolidinium-tetrafluoroborate, 1-ethyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide, 1-methyl-1-propylpyrrolidinium-bis(trifluoromethylsulfonyl)imide, and 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide. 
     
     
         10 . The electrolytic composition of  claim 1 , wherein the ratio of the solvent to ionic liquid is from about 40%:60% to about 80%:20% by volume. 
     
     
         11 . The electrolytic composition of  claim 1 , wherein the salt is a magnesium salt. 
     
     
         12 . The electrolytic composition of  claim 11 , wherein the salt is selected from the group consisting of magnesium bis(trifluoromethylsulfonyl)imide, magnesium bis(fluorosulfonyl)imide, and magnesium perchlorate. 
     
     
         13 . The electrolytic composition of  claim 1 , wherein at least one of the solvents exhibits a dissociation energy for Group 2 cations less than 600 kJ/mol. 
     
     
         14 . The electrolytic composition of  claim 1 , wherein the electrolytic composition exhibits a viscosity of 40 mPa·s to 165 mPa·s. 
     
     
         15 . The electrolytic composition of  claim 1  wherein the ionic liquid and the solvent form a blend, wherein the blend is an electrolyte. 
     
     
         16 . An electrochemical storage device comprising an electrolyte, an anode comprising magnesium and a cathode, wherein the electrolyte is an electrolytic composition comprising a blend of an ionic liquid and one or more solvents chosen from the group consisting of ethers and nitriles, and a Group 2 salt, an anode and a cathode. 
     
     
         17 . The electrochemical storage device of  claim 16 , wherein the anode comprises magnesium. 
     
     
         18 . The electrochemical storage device of  claim 17 , wherein the magnesium is in the form of a magnesium alloy or magnesium intermetallic. 
     
     
         19 . The electrochemical storage device of  claim 17 , wherein the magnesium is in the form of magnesium metal. 
     
     
         20 . The electrochemical storage device of  claim 16 , wherein the cathode comprises a metal oxide. 
     
     
         21 . The electrochemical storage device of  claim 16 , wherein the cathode comprises a metal sulfide. 
     
     
         22 . The electrochemical storage device of  claim 16 , wherein the cathode comprises a metal selenide. 
     
     
         23 . The electrochemical storage device of  claim 16 , wherein the cathode comprises a metal phosphate. 
     
     
         24 . The electrochemical storage device of  claim 16 , further comprising:
 a separator film, the separator film positioned in between the anode and the cathode; and   wherein the electrolyte exhibits a contact angle on the separator film of less than 100°.   
     
     
         25 . The electrochemical storage device of  claim 24 , wherein the electrolyte exhibits a contact angle on the separator film of less than 54°. 
     
     
         26 . The electrolytic composition of  claim 1 , wherein the salt is chosen from the group consisting of a magnesium bis(fluorosulfonyl)imide salt and a magnesium perchlorate salt. 
     
     
         27 . The electrolytic composition of  claim 26 , wherein the salt is a magnesium bis(fluorosulfonyl)imide salt. 
     
     
         28 . The electrolytic composition of  claim 26 , wherein the salt is a magnesium perchlorate salt. 
     
     
         29 . The electrochemical storage device of  claim 24 , wherein the separator film comprises polyethylene. 
     
     
         30 . The electrochemical storage device of  claim 24 , wherein the separator film comprises polypropylene.