Separators, articles and methods of making thereof

1. A separator 104 , comprising

a porous polyetherimide membrane comprising a plurality of pores,

wherein at least a portion of the pores comprise an electrolyte composition comprising an ionic liquid; wherein the ionic liquid is in a liquid state at a temperature of below 100° C.

2. The separator of claim 1 , wherein the separator has one or more of the following properties:

an ionic liquid contact angle of less than or equal to 50°;

a thickness of 5 micrometers to 200 micrometers;

a basis weight of 2 to 40 g/m 2 ;

a porosity of 10% to 90%;

an average pore size is 2 nm to 2000 nm;

a Gurley air permeability of 10 to 1000 s/100 cc;

a dimensional stability of >120° C.; or

a normalized dry weight of greater than or equal to 90% after 7 days at 55° C. in the ionic liquid.

3. The separator of claim 1 , wherein the polyetherimide comprises repeating units of the formula

wherein

each R is independently a substituted or unsubstituted C 6-20 aromatic hydrocarbon group, a substituted or unsubstituted, straight or branched chain C 4-20 alkylene group, a substituted or unsubstituted C 3-8 cycloalkylene group, or a combination comprising at least one of the foregoing; and

each Z is independently an aromatic C 6-24 monocyclic or polycyclic group optionally substituted with 1 to 6 C 1-8 alkyl groups, 1 to 8 halogen atoms, or a combination comprising at least one of the foregoing.

4. The separator of claim 3 , wherein

R is a divalent group of the formula

wherein Q 1 is —O—, —S—, —C(O)—, —SO 2 —, —SO—, —P(R a )(═O)— wherein R a is a C 1-8 alkyl or C 6-12 aryl, —C y H 2y — wherein y is an integer from 1 to 5 or a halogenated derivative thereof (which includes perfluoroalkylene groups), or —(C 6 H 10 ) z — wherein z is an integer from 1 to 4; and

Z is a group derived from a dihydroxy compound of the formula (3)

wherein

R a and R b are each independently a halogen atom or a monovalent C 1-6 alkyl group;

p and q are each independently integers of 0 to 4;

c is 0 to 4; and

X a is a single bond, —O—, —S—, —S(O)—, —SO 2 —, —C(O)—, or a C 1-18 organic bridging group.

5. The separator of claim 3 , wherein each R is independently meta-phenylene, para-phenylene, bis(4,4′-phenylene)sulfone, bis(3,4′-phenylene)sulfone, bis(3,3′-phenylene)sulfone, or a combination comprising at least one of the foregoing, and each Z is 4,4′-diphenylene isopropylidene.

6. The separator of claim 5 , wherein at least 50 mole percent of the R groups are bis(3,4′-phenylene)sulfone, bis(3,3′-phenylene)sulfone, or a combination comprising at least one of the foregoing.

7. The separator of claim 3 , wherein each R is meta-phenylene, bis(4,4′-phenylene)sulfone, bis(3,4′-phenylene)sulfone, bis(3,3′-phenylene)sulfone, or a combination comprising at least one of the foregoing.

8. The separator of claim 1 , wherein the polyetherimide further comprises siloxane blocks of the formula

wherein E has an average value of 2 to 100, and each R′ is independently a C 1-13 monovalent hydrocarbyl group,

preferably wherein the poly(siloxane-etherimide) has units of the formula

wherein

E has an average value of 2 to 100,

each R′ is independently a methyl group,

R 4 is a C 2 -C 20 alkylene group, and

n is an integer from 5 to 100.

9. The separator of claim 1 , wherein the ionic liquid comprises

an imidazolium cation, an isoquinolinium cation, a sulfonium cation, an ammonium cation, a pyridinium cation, a phosphonium cation, a pyrrazolium cation, a pyrrolidinium cation, a piperidinium cation, a dicationic species, or a combination comprising at least one of the foregoing; and

a bis(fluorosulfonyl)imide anion, a bis(trifluoromethane)sulfonimide anion, a bis(pentafluoroethylsulfonyl)amide anion, a (fluorosulfonyl)(trifluoromethylsulfonyl)amide anion, a tetrafluoroborate anion, a hexafluorophosphate anion, a bis(fluorosulfonyl)imide anion; a bis(perfluoroethylsulfonyl)imide anion, a bis(trifluoromethanesulfonyl)imide anion, a triflate anion, a tetrachloroaluminate anion, 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide, aluminum chloride, Cl − , F − , S 2− , or a combination comprising at least one of the foregoing.

10. The separator of claim 1 , wherein the electrolyte further comprises a lithium salt.

11. The separator of claim 1 , wherein the separator 104 comprises a multilayer structure.

12. The separator of claim 11 , wherein the porous polyetherimide membrane is in the form of a coating disposed on at least a portion of a porous substrate.

13. A method of preparing the separator 104 of claim 1 , comprising

dissolving a polyetherimide in a solvent at room temperature to 210° C., to form a solution,

casting the solution at a temperature of 20 to 50° C. to form a thin film,

coagulating the thin film in a coagulating bath comprising a nonsolvent for the polyetherimide, and optionally a solvent for the polyetherimide to provide the porous polyetherimide membrane, and

contacting the porous polyetherimide membrane with the electrolyte composition to fill at least a portion of the plurality of pores to provide the separator.

14. The method of claim 13 , wherein casting the solution at a temperature of 20 to 50° C. to form the thin film comprises casting the solution on at least a portion of a porous polyolefin substrate to provide a coating on the porous polyolefin substrate.

15. The method of claim 13 , wherein the solvent is 2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-cyclohexyl-2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, 1-octyl-2-pyrrolidone, 1-N-ethoxycarbonyl-3-pyrrolidone, N-methyl-2-pyrrolidone, 1-vinyl-2-pyrrolidone, dimethylformamide, dimethylacetamide or a combination comprising at least one of the foregoing.

16. The method of claim 13 , wherein the solvent is 4-chloro-3-methyl-phenol, 4-chloro-2-methyl-phenol, 2,4-dichloro-6-methyl-phenol, 2,4-dichloro-phenol, 2,6-dichloro-phenol, 4-chloro-phenol, 2-chloro-phenol, o-cresol, m-cresol, p-cresol, 4-methoxy-phenol, catechol, benzoquinone, 2,3-xylenol, 2,6-xylenol, resorcinol, or a combination comprising at least one of the foregoing.

17. A system comprising

an anode 102 ,

a cathode 100 ,

the separator 104 of claim 1 disposed between the anode 102 and the cathode 100 , and

the electrolyte comprising the ionic liquid 108 in contact with the anode 102 , the cathode 100 , and the separator 104 .

18. The system of claim 17 , in the form of an electrochemical cell.

19. The system of claim 18 , wherein the electrochemical cell is a lithium-ion battery.