Electrolyte for lithium ion batteries
View Patent ↗A non-aqueous electrolyte usable in rechargeable lithium-ion batteries including a solution of LiPF 6 /carbonate based electrolytes with low concentrations of LiFOP such that the thermal stability is increased compared to a standard lithium battery. A method of making lithium tetrafluorophospahte (LiF 4 C 2 O 4 , LiFOP) including, reacting PF 5 with lithium oxalate, recrystallizing DMC/dichloromethane from a 1:1 mixture of to separate LiF 4 OP from LiPF 6 to form a lithium salt. An electric current producing rechargeable Li-ion cell. The rechargeable lithium ion cell includes an anode, a cathode, and a non-aqueous electrolyte comprising a solution of a lithium salt in a non-aqueous organic solvent containing lithium tetrafluorooxalatophosphate (LiPF 4 (C 2 O 4 ), LiF 4 OP).
1. A method of making lithium tetrafluorophosphate (represented by LiPF 4 C 2 O 4 , or LiF 4 OP) for use as a lithium ion battery electrolyte, said method consisting essentially of the steps of:
heating solid LiPF 6 to 200° C. to produce PF 5 gas;
reacting the PF 5 gas with lithium oxalate; and
recrystallizing from a 1:1 mixture of dimethyl carbonate (DMC)/dichloromethane to separate LiF 4 OP from LiPF 6 to form a lithium salt.
2. The method as claimed in claim 1 , wherein said lithium tetrafluorophosphate is lithium tetrafluoro oxalato phosphate (represented by LiPF 4 C 2 O 4 ).
3. The method as claimed in claim 1 , wherein the LiPF 6 is provided in a solution of LiPF 6 /carbonate based electrolytes with low concentrations of LiFOP of about 0.1-5.0% by wt.
4. The method as claimed in claim 1 , wherein the LiPF 6 is provided in a solution of LiPF 6 /carbonate based electrolytes with high concentrations of LiFOP of about 5.0-95.0% by wt.
5. The method as claimed in claim 1 , wherein said lithium ion salt is:
6. A method of making lithium tetrafluorophosphate (represented by LiPF 4 C 2 O 4 , or LiF 4 OP,) for use as a lithium ion battery electrolyte, said method consisting essentially of the steps of:
heating solid LiPF 6 to 200° C. to generate a PF 5 gas;
reacting the PF 5 gas with lithium oxalate to provide a reaction mixture;
stirring the reaction mixture; and
recrystallizing from a 1:1 mixture of dimethyl carbonate/dichloromethane to remove LiPF 6 from LiF 4 OP to form a lithium salt.
7. The method as claimed in claim 6 , wherein said steps of stirring the reaction mixture and recrystallizing from the 1:1 mixture of dimethyl carbonate/dichloromethane are repeated.
8. The method as claimed in claim 6 , wherein said step of stirring the reaction mixture is performed at a temperature of about 25° C.
9. The method as claimed in claim 6 , wherein said method further has the step of transferring the PF 5 gas via a stream of N 2 into a suspension of lithium oxalate in dimethyl carbonate.
10. The method as claimed in claim 9 , wherein said suspension of lithium oxalate in dimethyl carbonate is provided at about 25° C.