Electrolyte for stable cycling of rechargeable alkali metal and alkali ion batteries

Abstract

Localized superconcentrated electrolytes (LSEs) and electrochemical devices including the LSEs are disclosed. The LSE includes an active salt, a solvent in which the active salt is soluble, and a diluent in which the active salt is insoluble or poorly soluble, wherein the diluent includes a fluorinated orthoformate.

We claim: 
     
         1 . An electrolyte, comprising:
 an active salt;   a solvent comprising an ether, a carbonate, a sulfone, an aliphatic ester, a lactone, a sulfoxide, water, a flame retardant compound, a nitrile, or any combination thereof, wherein the active salt is soluble in the solvent; and   a fluorinated orthoformate, wherein the active salt has a solubility in the fluorinated orthoformate at least 10 times less than a solubility of the active salt in the solvent, and wherein a molar concentration of the active salt in the electrolyte is 20% less than to 80% less than a molar concentration of the active salt in the solvent in the absence of the fluorinated orthoformate.   
     
     
         2 . The electrolyte of  claim 1 , wherein:
 (i) the solubility of the active salt in the solvent is greater than 3 moles of active salt per liter of the solvent; or   (ii) the active salt has a concentration in the electrolyte of 0.1 M to 3 M; or   (iii) a molar ratio of the active salt to the solvent is 0.1 to 5; or   (iv) any combination of two or more of (i), (ii), and (iii).   
     
     
         3 . The electrolyte of  claim 1 , wherein the fluorinated orthoformate is tris(2,2,2-trifluoroethyl)orthoformate (TFEO), tris(hexafluoroisopropyl)orthoformate (THFiPO), tris(2,2-difluoroethyl)orthoformate (TDFEO), bis(2,2,2-trifluoroethyl) methyl orthoformate (BTFEMO), tris(2,2,3,3,3-pentafluoropropyl)orthoformate (TPFPO), tris(2,2,3,3-tetrafluoropropyl)orthoformate (TTPO), or any combination thereof. 
     
     
         4 . The electrolyte of  claim 1 , wherein the solvent comprises 1,2-dimethoxyethane (DME), 1,3-dioxolane (DOL), allyl ether, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), 4-vinyl-1,3-dioxolan-2-one (VEC), 4-methylene-1,3-dioxolan-2-one (MEC), 4,5-dimethylene-1,3-dioxolan-2-one, dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS), methyl butyrate, ethyl propionate, trimethyl phosphate, triethyl phosphate, gamma-butyrolactone, dimethyl sulfoxide (DMSO), triallyl amine, triallyl cyanurate, triallyl isocyanurate, water, acetonitrile, or any combination thereof. 
     
     
         5 . The electrolyte of  claim 1 , wherein the flame retardant compound comprises an organic phosphate, an organic phosphite, an organic phosphonate, an organic phosphoramide, a phosphazene, or any combination thereof. 
     
     
         6 . The electrolyte of  claim 1 , wherein the active salt comprises a lithium salt or lithium salts mixture, a sodium salt or sodium salts mixture, a potassium salt or potassium salts mixture, or a magnesium salt or magnesium salts mixture. 
     
     
         7 . The electrolyte of  claim 1 , wherein the active salt comprises lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl trifluoromethanesulfonyl)imide (LiFTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(oxalato)borate (LiBOB), LiPF 6 , LiAsF 6 , LiBF 4 , LiCF 3 SO 3 , LiClO 4 , lithium difluoro oxalato borate anion (LiDFOB), LiI, LiBr, LiCl, LiSCN, LiNO 3 , LiNO 2 , Li 2 SO 4 , sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium bis(pentafluoroethanesulfonyl)imide (NaBETI), NaPF 6 , NaAsF 6 , NaBF 4 , NaCF 3 SO 3 , NaClO 4 , sodium bis(oxalato)borate (NaBOB), sodium difluoro oxalato borate anion (NaDFOB), or any combination thereof. 
     
     
         8 . The electrolyte of  claim 1 , further comprising a linear fluoroalkyl ether. 
     
     
         9 . The electrolyte of  claim 8 , wherein the linear fluoroalkyl ether comprises 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2,-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE), methoxynonafluorobutane (MOFB), ethoxynonafluorobutane (EOFB), or any combination thereof. 
     
     
         10 . A battery, comprising:
 an electrolyte according to  claim 1 ;   an anode comprising an alkali metal, carbon, silicon, a carbon/silicon composite, tin, or antimony, or an anode current collector in the absence of an anode; and   a cathode.   
     
     
         11 . An electrolyte, comprising:
 an active salt;   a solvent comprising an ether, a carbonate, a sulfone, an aliphatic ester, a lactone, a sulfoxide, water, a flame retardant compound, a nitrile, or any combination thereof, wherein the active salt is soluble in the solvent; and   a fluorinated orthoformate, wherein the active salt has a solubility in the fluorinated orthoformate at least 10 times less than a solubility of the active salt in the solvent, and wherein a volumetric ratio of the solvent to the fluorinated orthoformate is from 0.2 to 5.   
     
     
         12 . The electrolyte of  claim 11 , wherein:
 (i) the solubility of the active salt in the solvent is greater than 3 moles of active salt per liter of the solvent; or   (ii) the active salt has a concentration in the electrolyte of 0.1 M to 3 M; or   (iii) a molar ratio of the active salt to the solvent is within a range of from 0.1 to 5; or   (iv) any combination of two or more of (i), (ii), and (iii).   
     
     
         13 . The electrolyte of  claim 11 , wherein the fluorinated orthoformate is tris(2,2,2-trifluoroethyl)orthoformate (TFEO), tris(hexafluoroisopropyl)orthoformate (THFiPO), tris(2,2-difluoroethyl)orthoformate (TDFEO), bis(2,2,2-trifluoroethyl) methyl orthoformate (BTFEMO), tris(2,2,3,3,3-pentafluoropropyl)orthoformate (TPFPO), tris(2,2,3,3-tetrafluoropropyl)orthoformate (TTPO), or any combination thereof. 
     
     
         14 . The electrolyte of  claim 11 , wherein the solvent comprises 1,2-dimethoxyethane (DME), 1,3-dioxolane (DOL), allyl ether, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), 4-vinyl-1,3-dioxolan-2-one (VEC), 4-methylene-1,3-dioxolan-2-one (MEC), 4,5-dimethylene-1,3-dioxolan-2-one, dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS), methyl butyrate, ethyl propionate, trimethyl phosphate, triethyl phosphate, gamma-butyrolactone, dimethyl sulfoxide (DMSO), triallyl amine, triallyl cyanurate, triallyl isocyanurate, water, acetonitrile, or any combination thereof. 
     
     
         15 . The electrolyte of  claim 11 , wherein the flame retardant compound comprises an organic phosphate, an organic phosphite, an organic phosphonate, an organic phosphoramide, a phosphazene, or any combination thereof. 
     
     
         16 . The electrolyte of  claim 11 , wherein the active salt comprises a lithium salt or lithium salts mixture, a sodium salt or sodium salts mixture, a potassium salt or potassium salts mixture, or a magnesium salt or magnesium salts mixture. 
     
     
         17 . The electrolyte of  claim 11 , wherein the active salt comprises lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl trifluoromethanesulfonyl)imide (LiFTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(oxalato)borate (LiBOB), LiPF 6 , LiAsF 6 , LiBF 4 , LiCF 3 SO 3 , LiClO 4 , lithium difluoro oxalato borate anion (LiDFOB), LiI, LiBr, LiCl, LiSCN, LiNO 3 , LiNO 2 , Li 2 SO 4 , sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium bis(pentafluoroethanesulfonyl)imide (NaBETI), NaPF 6 , NaAsF 6 , NaBF 4 , NaCF 3 SO 3 , NaClO 4 , sodium bis(oxalato)borate (NaBOB), sodium difluoro oxalato borate anion (NaDFOB), or any combination thereof. 
     
     
         18 . The electrolyte of  claim 11 , further comprising a linear fluoroalkyl ether. 
     
     
         19 . The electrolyte of  claim 18 , wherein the linear fluoroalkyl ether comprises 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), bis(2,2,2-trifluoroethyl) ether (BTFE),  1 , 1 , 2 , 2 ,-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE), methoxynonafluorobutane (MOFB), ethoxynonafluorobutane (EOFB), or any combination thereof. 
     
     
         20 . A battery, comprising:
 an electrolyte according to  claim 11 ;   an anode comprising an alkali metal, carbon, silicon, a carbon/silicon composite, tin, or antimony, or an anode current collector in the absence of an anode; and   a cathode.