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

Patent metadata

Field	Value
Publication number	US-2020161706-A1
Application number	US-201916688929-A
Country	US
Kind code	A1
Filing date	Nov 19, 2019
Priority date	Nov 21, 2018
Publication date	May 21, 2020
Grant date	—

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.

First claim

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 diluent comprising a fluorinated orthoformate, wherein the active salt has a solubility in the diluent at least 10 times less than a solubility of the active salt in the solvent.

2 . 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.

3 . 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 (i.e. methylene ethylene carbonate (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.

4 . The electrolyte of claim 1 , wherein the solvent comprises a flame retardant compound, and the electrolyte comprises at least 5 wt % of the flame retardant compound.

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 5 , wherein the flame retardant compound comprises trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) methyl phosphate; trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite; dimethyl methylphosphonate, diethyl ethylphosphonate, diethyl phenylphosphonate, bis(2,2,2-trifluoroethyl) methylphosphonate; hexamethylphosphoramide; hexamethoxyphosphazene, hexafluorophosphazene, or any combination thereof.

7 . 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.

8 . 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.

9 . The electrolyte of claim 1 , wherein:
(i) the active salt has a molar concentration in the electrolyte within a range of from 0.1 M to 3M; or (ii) the active salt has a molar concentration in the electrolyte of greater than 3 moles of active salt per liter of the solvent; or (iii) the molar concentration of the active salt in the electrolyte is at least 20% less than a molar concentration of the active salt in the solvent in the absence of the diluent; or (iv) a molar ratio of the active salt to the solvent is within a range of from 0.1 to 5; or (v) a molar ratio of the solvent to the diluent is within a range of from 0.1 to 5; or (vi) any combination of (i), (ii), (iii), (iv), and (v).

10 . The electrolyte of claim 1 , wherein the diluent further comprises a linear fluoroalkyl ether.

11 . The electrolyte of claim 1 , wherein the solvent and the diluent are immiscible, the electrolyte further comprising a bridge solvent having a different composition than the solvent and a different composition than the diluent, wherein the bridge solvent is miscible with the solvent and with the diluent.

12 . The electrolyte of claim 11 , wherein the bridge solvent comprises acetonitrile, dimethyl carbonate, diethyl carbonate, propylene carbonate, dimethyl sulfoxide, 1,3-dioxolane, 1,2-dimethoxyethane, diglyme (bis(2-methoxyethyl) ether), triglyme (triethylene glycol dimethyl ether), tetraglyme (tetraethylene glycol dimethyl ether), or any combination thereof.

13 . The electrolyte of claim 1 , wherein:
the active salt is (i) LiFSI, LiTFSI, or a combination thereof, or (ii) NaFSI, NaTFSI, or a combination thereof; the solvent comprises an ether, a flame retardant compound comprising an organic phosphate, or a combination thereof; and the diluent comprises TFEO, TDFEO, or TFEO and TDFEO.

14 . A battery, comprising:
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,
a diluent comprising a fluorinated orthoformate, wherein the active salt has a solubility in the diluent at least 10 times less than a solubility of the active salt in the solvent, and the active salt has a concentration in the electrolyte within a range of 0.1 to 3 M;
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, wherein the battery has a coulombic efficiency 95%.

15 . The battery of claim 14 , wherein the fluorinated orthoformate comprises 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.

16 . The battery of claim 14 , wherein the electrolyte comprises at least 5 wt % of a flame retardant compound.

17 . The battery of claim 14 , wherein the solvent further comprises a flame retardant compound comprising triethyl phosphate, trimethyl phosphate, or a combination thereof;

18 . The battery of claim 14 , wherein:
the active salt comprises LiFSI, LiTFSI, LiFTFSI, LiBETI, LiPF 6 , LiAsF 6 , LiBF 4 , LiCF 3 SO 3 , LiClO 4 , LiBOB, LiDFOB, LiI, LiBr, LiCl, LiSCN, LiNO 3 , LiNO 2 , Li 2 SO 4 , or any combination thereof; the solvent comprises an ether, an organic phosphate, an organic phosphite, DMC, EC, EMC, DEC, PC, MFEC, VC, FEC, DFEC, TFEC, VEC, MEC, ethylene sulfite, ethylene sulfate, EVS, water, or any combination thereof; the diluent comprises TFEO, THFiP

Assignees

• Battelle Memorial Institute

Inventors

• Cao Xia
• Zhang Ji-Guang
• Xu Wu

Classifications

• H01M10/0567 Primary

  characterised by the additives · CPC title

• H01M10/0568

  characterised by the solutes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M10/0569

  characterised by the solvents · CPC title

• H01M2300/0025

  Organic electrolyte · CPC title