Solid polymer electrolyte composition
A polymer electrolyte composition includes a hard polymer segment covalently bound to an ionically-conducting segment, and a salt that includes an element M selected from an alkali metal, an alkaline earth metal, zinc, and aluminum. The hard polymer segment has a glass transition temperature (T g ) greater than or equal to 110° C., or a melting temperature (T m ) greater than 110° C. The ionically-conducting segment has a molecular weight of 800 to 10,000 g/mol. The polymer electrolyte composition has an ionic conductivity for an M ion greater than or equal to 1×10 −8 S/cm at 25° C. Methods for the preparation of the polymer electrolyte composition are also provided, as are articles (e.g., electrochemical cells and energy storage devices) that contain the polymer electrolyte composition.
1. A polymer electrolyte composition comprising:
a plurality of hard polymer segments having:
(a) a glass transition temperature (T g ) greater than or equal to 110° C.; or
(b) a melting temperature (T m ) greater than 110° C.;
an ionically-conducting segment, said ionically-conducting segment having a molecular weight of 800 to 10,000 g/mol; and
a salt comprising an element M, wherein M is selected from an alkali metal, an alkaline earth metal, zinc, and aluminum,
wherein:
at least one of the hard polymer segments is covalently bound to the ionically-conducting segment;
the ionically-conducting segment comprises a structural unit having the formula:
wherein a represents a number from 40 to 130; and
said polymer electrolyte composition has an ionic conductivity for an M ion greater than or equal to 1×10 −8 S/cm at 25° C.
2. The polymer electrolyte composition according to claim 1 , said polymer electrolyte composition having an ionic conductivity for M ion greater than 1×10 −5 S/cm at 25° C.
3. The polymer electrolyte composition according to claim 1 , further comprising a plasticizer.
4. The polymer electrolyte composition according to claim 3 , wherein the plasticizer comprises polyethylene glycol dimethyl ether.
5. The polymer electrolyte composition according to claim 1 , wherein M is selected from an alkali metal and an alkaline earth metal.
6. The polymer electrolyte composition according to claim 1 , wherein at least one of the hard polymer segment comprises a C 15 to C 80 alkyl group.
7. The polymer electrolyte composition according to claim 1 , wherein at least one of the hard polymer segments comprises polyethylene.
8. The polymer electrolyte composition according to claim 1 , wherein a represents a number from 70 to 90.
9. The polymer electrolyte composition according to claim 1 , wherein the ionically-conducting segment comprises a residue from a precursor compound of the formula (I):
wherein a represents a number from 40 to 130.
10. The polymer electrolyte composition according to claim 1 , wherein:
M is lithium;
said polymer electrolyte composition has an ionic conductivity for Li + greater than or equal to 1×10 −6 S/cm at 25° C.; and
said polymer electrolyte composition has a lithium dendrite growth resistance (C d ) value greater than or equal to 1000 C/cm 2 at current density (J) value of 0.26 mA/cm 2 and 90° C.
11. The polymer electrolyte composition according to claim 10 , wherein a represents a number from 70 to 90.
12. The polymer electrolyte composition according to claim 1 , wherein:
at least one of the hard polymer segments comprises polyethylene; and
the salt is a lithium salt.
13. The polymer electrolyte composition according to claim 12 , wherein a represents a number from 70 to 90.
14. The polymer electrolyte composition according to claim 12 , wherein the ionically-conducting segment comprises a residue from a precursor compound of the formula (I):
wherein a represents a number from 40 to 130.
15. The polymer electrolyte composition according to claim 12 , wherein the lithium salt is selected from the group consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTF SI), lithium hexafluorophosphate (LiPF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO3), lithium perchlorate (LiCIO 4 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(trifluoromethanesulfonimide) (LiN(CF 3 SO 2 ) 2 ), lithium bis(perfluoroethylsulfonylimide) (LiN(C 2 F 5 SO 2 ) 2 ), lithium thiocyanate (Li SCN), lithium dicyanamide (LiN(CN) 2 ), lithium tris (trifluoromethanesulphonyl)methyl (LiC(CF 3 SO 2 ) 3 ), lithium bisoxalatoborate (LiB(C 2 O 4 ) 2 ), lithium oxalatoborates, lithium bis(chelato)borate, lithium alkyl fluorophosphates, LiPF 3 (C 2 F 5 ) 3 , and LiPF 3 (CF 3 ) 3 .
16. The polymer electrolyte composition according to claim 15 , wherein the lithium salt is LiTFSI.
17. An electrochemical cell comprising a separator, said separator comprising the polymer electrolyte composition according to claim 1 .
18. An energy storage device comprising a plurality of electrochemical cells, wherein at least one of the plurality of electrochemical cells is an electrochemical cell according to claim 17 .
19. The polymer electrolyte composition according to claim 1 , having a polymer framework that is crosslinked, wherein at least two hard polymer segments are covalently bound to the ionically-conducting segment.