MULTI-LITHIUM SALT ELECTROLYTE AND LITHIUM-BASED BATTERY COMPRISING THE SAME
A lithium-based battery including an electrolyte having at least two lithium salts selected from LiPF 6 , LiTFSI, LiFSI or LiBF 4 , along with a further lithium salt additive. Through the selection of particular lithium salt combinations, a high lithium ion concentration in the electrolyte is maintained. The battery includes a cathode, an anode, and a porous polymer separator. The lithium-based battery has reliable capacity retention at high discharge rates, such as 10C to 15C.
1 . A lithium-based battery comprising:
a cathode selected from lithium manganese oxide, lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium iron phosphate or combinations thereof;
an electrolyte including a lithium hexafluorophosphate first salt and at least one second lithium salt selected from lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide or lithium tetrafluoroborate;
wherein the molar ratio of lithium hexafluorophosphate to the second lithium salt ranges from 15:1 to 1:6 and a concentration in the electrolyte of the first salt and the at least one second salt is from approximately 1.5M to approximately 5M;
wherein the electrolyte further comprises a lithium salt additive in an amount from 0.1% to 5% of a total weight of the electrolyte;
an anode selected from silicon, silicon oxide, carbon nanotubes, lithium metal, graphene, graphite or combinations thereof; and
a porous polymer separator.
2 . The lithium-based battery of claim 1 , wherein the electrolyte has a lithium hexafluorophosphate concentration of 0.5M to 1.5M.
3 . The lithium-based battery of claim 2 , wherein the electrolyte has a lithium bis(trifluoromethanesulfonyl)imide concentration and/or lithium bis(fluorosulfonyl)imide concentration and/or lithium tetrafluoroborate concentration of 0.1M to 3.0M.
4 . The lithium-based battery of claim 1 , wherein the lithium salt additive is lithium difluoro(oxalato)borate lithium bis(oxalate) borate, lithium difluoro(bisoxalato)phosphate, or lithium difluorophosphate.
5 . The lithium-based battery of claim 1 , wherein the molar ratio of lithium hexafluorophosphate to the one or more second lithium salt ranges from 2:1 to 2:3.
6 . The lithium-based battery of claim 1 , wherein the electrolyte further comprises a solvent selected from ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate or combinations thereof.
7 . The lithium-based battery of claim 6 , wherein ethylene carbonate has a volume percentage of 20% to 70% based on the volume of the solvent.
8 . The lithium-based battery of claim 6 , wherein diethyl carbonate has a volume percentage of 2% to 50% based on the volume of the solvent.
9 . The lithium-based battery of claim 6 , wherein ethyl methyl carbonate has a volume percentage of 2% to 60% based on the volume of the solvent.
10 . The lithium-based battery of claim 6 , wherein dimethyl carbonate has a volume percentage of 2% to 60% based on the volume of the solvent.
11 . The lithium-based battery of claim 1 , wherein the electrolyte further comprises an additive selected from fluoroethylene carbonate, vinylene carbonate, 1,3-propane sultone, propylene carbonate, or combinations thereof.
12 . The lithium-based battery of claim 1 , wherein the additive is fluoroethylene carbonate in an amount of 0.1 to 5 wt % based on the electrolyte.
13 . The lithium-based battery of claim 1 , wherein the additive is vinylene carbonate in an amount of 0.1 to 5 wt % based on the electrolyte.
14 . The lithium-based battery of claim 1 , wherein the additive is 1,3-propane sultone in an amount of 0.1 to 5 wt % based on the electrolyte.
15 . The lithium-based battery of claim 1 , wherein the additive is propylene carbonate in an amount of 0.1 to 10 wt % or less based on the electrolyte.
16 . The lithium-based battery of claim 1 , wherein the porous polymer separator has a porosity of about 30% to 90%.