Electrolyte comprising a phosphite as an additive or co-solvent, lithium rechargeable battery comprising said electrolyte, and method for producing the phosphite
An electrolyte includes at least one lithium salt, at least one first organic solvent having a dielectric constant of >90 at 40° C., at least one second organic solvent having a boiling point of <110° C., and at least one phosphite having the formula (I) R 1 is selected from an n-propoxy group, an iso-propoxy group, a tert-butoxy group, an n-pentafluoropropoxy group, an n-trifluoropropoxy group, an iso-hexafluoropropoxy group, or a tert-nonafluorobutoxy group. R 2 , R 3 , R 4 , and R 5 are each selected, independently of one another, from H, a trifluoromethyl group, or a C 2 -C 6 -alkyl group which is substituted with a trifluoromethyl group.
1. An electrolyte comprising:
at least one lithium salt;
at least one first organic solvent having a dielectric constant of >90 at 40° C.;
at least one second organic solvent having a boiling point of <110° C.; and
at least one phosphite having the formula (I)
wherein,
R 1 is an n-propoxy group, an iso-propoxy group, a tert-butoxy group, an n-pentafluoropropoxy group, an n-trifluoropropoxy group, an iso-hexafluoropropoxy group, or a tert-nonafluorobutoxy group, and
R 2 , R 3 , R 4 , and R 5 are each selected, independently of one another, from H, a trifluoromethyl group, or a C 2 -C 6 -alkyl group which is substituted with a trifluoromethyl group.
2. The electrolyte as recited in claim 1 , wherein R 1 is the n-propoxy group, the iso-propoxy group, or the tert-butoxy group.
3. The electrolyte as recited in claim 2 , wherein R 1 is the tert-butoxy group.
4. The electrolyte as recited in claim 1 , wherein R 1 is the n-pentafluoropropoxy group.
5. The electrolyte as recited in claim 1 , wherein,
R 2 is the trifluoromethyl group, and
R 3 , R 4 , and R 5 are each H.
6. The electrolyte as recited in claim 1 , wherein R 2 , R 3 , R 4 , and R 5 are each H.
7. The electrolyte as recited in claim 1 , wherein the electrolyte comprises 0.1 to 15 wt.-% of the at least one phosphite relative to a total weight of the at least one first organic solvent and the at least one second organic solvent.
8. A method of using an electrolyte in a rechargeable lithium battery at a voltage above 4.2 V, the method comprising:
providing the electrolyte comprising,
at least one lithium salt,
at least one first organic solvent having a dielectric constant of >90 at 40° C.,
at least one second organic solvent having a boiling point of <110° C., and
at least one phosphite having the formula (I)
wherein,
R 1 is a completely or partially halogen-substituted, linear or branched, C 2 -C 20 alkyl group, and
R 2 , R 3 , R 4 , and R 5 are each selected, independently of one other, from H, or an unsubstituted or completely or partially halogen-substituted, linear or branched, C 1 -C 20 alkyl group;
providing the electrolyte as a part of the rechargeable lithium battery; and
using the electrolyte in the rechargeable lithium battery at the voltage above 4.2 V.
9. A rechargeable lithium battery comprising:
a cathode;
an anode;
a separator; and
the electrolyte as recited in claim 1 .
10. The rechargeable lithium battery as recited in claim 9 , wherein the electrolyte comprises 0.1 to 15 wt.-% of the at least one phosphite relative to a total weight of the at least one first organic solvent and the at least one second organic solvent.