Poly(alkylene oxide) siloxane-based electrolytes for rechargeable batteries

1. An electrochemical device comprising:

a cathode comprising elemental selenium, elemental sulfur, or a selenium-sulfur composite of formula S x Se y , wherein 0.1<x/y<50;

a negative electrode;

a separator; and

an electrolyte comprising:

a poly(alkyleneoxide) siloxane; and

a salt;

wherein:

a concentration of the salt in the electrolyte is from greater than 2 M to 10 M, and the molarity is determined as moles of salt divided by the volume of the electrolyte, without considering the volume change of the electrolyte composition due to dissolution of the salt and is sufficient to prevent or suppress dissolution of polysulfides/polyselenides formed during cycling of the device.

2. The electrochemical device of claim 1 , wherein the concentration of the salt in the electrolyte is from about 5 M to 10 M, and the molarity is determined as moles of salt divided by the volume of the electrolyte, without considering the volume change of the electrolyte composition due to dissolution of the salt.

3. The electrochemical device of claim 1 , wherein the poly(alkyleneoxide) siloxane is a compound having at least one poly(alkylene oxide) (“PAO”) moiety on a silicon atom.

4. The electrochemical device of claim 1 , wherein:

the poly(alkyleneoxide) siloxane is a compound of Formula I:

SiR 1 (4-x) (PAO) x ;

x is 1, 2, or 3; and

PAO is a poly(alkyleneoxide) group;

each R 1 is independently hydrogen, a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to 12 carbon atoms, or a further siloxane group of Formula II:

—OSiR 2 (3-x′) (PAO) x′ ;

each R 2 is independently hydrogen, a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to 12 carbon atoms, or a further siloxane group of formula —OSiR 2 (3-x′) (PAO) x′ ; and

x′ is 0, 1, 2, or 3.

5. The electrochemical device of claim 4 , wherein the PAO is a group of Formula III:

—(CH 2 ) p [O(CH 2 ) n ] q (O) q ·R 3 ; and

wherein:

R 3 is H, alkyl, or a group of Formula IV

n is an integer from 1 to 12;

p is an integer from 0 to 12;

q represents a polymeric repeat unit;

q′ is 0 or 1; and

R 4 is H, alkyl, or alkenyl.

6. The electrochemical device of claim 5 , wherein q is from 1 to 1000.

7. The electrochemical device of claim 5 , wherein q is from 1 to 10.

8. The electrochemical device of claim 5 , wherein R 3 is H or a C 1 -C 12 alkyl.

9. The electrochemical device of claim 5 , wherein n is 1, 2, or 3.

10. The electrochemical device of claim 5 , wherein p is 0, 1, 2, or 3.

11. The electrochemical device of claim 5 , wherein R 4 is H, C 1 -C 10 alkyl, or C 1 -C 10 alkenyl.

12. The electrochemical device of claim 5 , wherein the PAO is a poly(ethylene oxide) or poly(propylene oxide) group.

13. The electrochemical device of claim 5 , wherein the poly(alkyleneoxide) siloxane is (CH 3 ) 3 SiO(CH 2 CH 2 O) n CH 3 , (CH 3 ) 3 SiCH 2 O(CH 2 CH 2 O) n CH 3 , Si[O(CH 2 CH 2 O) p′ CH 3 ] 4 , (CH 3 ) 3 Si(CH 2 ) 3 O(CH 2 CH 2 O) n CH 3 , (CH 3 ) 2 Si[O(CH 2 CH 2 O) n CH 3 ] 2 , CH 3 SiOR 3 , CH 3 Si[O(CH 2 CH 2 O) p CH 3 ] 3 , (CH 3 ) 2 Si[O(CH 2 CH 2 O) n CH 3 ][(CH 2 ) 3 —O—(CH 2 CH 2 O) n CH 3 ], (CH 3 ) 3 Si(CH 2 ) 3 OR 3 , CH 3 O(CH 2 CH 2 O) n SiO(CH 3 ) 2 O(CH 3 ) 2 SiO(CH 2 CH 2 O) n CH 3 , CH 3 O(CH 2 CH 2 O) n Si(CH 3 ) 2 O(CH 3 ) 2 SiO(CH 2 CH 2 O) n CH 3 , CH 3 O(CH 2 CH 2 O) n CH 2 Si(CH 3 ) 2 O(CH 3 ) 2 SiCH 2 O(CH 2 CH 2 O) n CH 3 , CH 3 O(CH 2 CH 2 O) n (CH 2 ) 3 Si(CH 3 ) 2 O(CH 3 ) 2 Si(CH 2 ) 3 O(CH 2 CH 2 O) n CH 3 , (CH 3 ) 3 SiO(CH 3 ) 2 Si(CH 2 ) 3 O(CH 2 CH 2 O) n CH 3 , (CH 3 ) 3 SiO(CH 3 ) 2 Si(CH 2 ) 2 O(CH 2 CH 2 O) n CH 3 , (CH 3 ) 3 SiO(CH 3 ) 2 SiO(CH 2 CH 2 O) n CH 3 , (CH 3 ) 3 SiO(CH 3 ) 2 SiOR 3 , R 3 OSi(CH 3 ) 2 O(CH 3 ) 2 SiOR 3 , (CH 3 ) 3 SiO(CH 3 ) 2 Si(CH 2 ) 3 OR 3 , R 3 O(CH 2 ) 3 Si(CH 3 ) 2 O(CH 3 ) 2 Si(CH 2 ) 3 OR 3 , CH 3 O(CH 2 CH 2 O) n Si(CH 3 ) 2 OSi(CH 3 ) 2 O(CH 3 ) 2 SiO(CH 2 CH 2 O) n CH 3 , CH 3 O(CH 2 CH 2 O) n′ (CH 2 ) 3 Si(CH 3 ) 2 OSi(CH 3 ) 2 O (CH 3 ) 2 Si(CH 2 ) 3 O(CH 3 ) 2 SiO(CH 2 CH 2 O) n′ CH 3 , [(CH 3 ) 3 SiO] 2 Si(CH 3 )O(CH 2 CH 2 O) n CH 3 , [(CH 3 ) 3 SiO] 2 Si(CH 3 )(CH 2 ) 3 O(CH 2 CH 2 O) n CH 3 , [(CH 3 ) 3 SiO] 2 Si(CH 3 )O(CH 2 CH 2 O) n CH 3 Si[OSi(CH 3 ) 3 ] 2 , R 3 OSi(CH 3 ) 2 OSi(CH 3 ) 2 O(CH 3 ) 2 SiOR 3 , R 3 OSi(CH 3 ) 2 OSi(CH 3 ) 2 OSi(CH 3 ) 3 , R 3 O(CH 2 ) 3 Si(CH 3 ) 2 OSi(CH 3 ) 2 O(CH 3 ) 2 Si(CH 2 ) 3 OR 3 , R 3 O(CH 2 ) 3 Si(CH 3 ) 2 OSi(CH 3 ) 2 OSi(CH 3 ) 3 , R 3 OSi(CH 3 ) 2 OSi(CH 3 ) 2 O(CH 3 ) 2 SiO(CH 2 CH 2 O) n CH 3 , R 3 O(CH 2 ) 3 Si(CH 3 ) 2 OSi(CH 3 ) 2 O(CH 3 ) 2 Si(CH 2 ) 3 O(CH 2 CH 2 ) n CH 3 , or a mixture of any two or more such poly(ethyleneoxide) siloxanes, wherein R 3 is a carbonate group of Formula IV; n is 2, 3, 4, 5, 6, or 7; n′ is 2, 3, 4, or 5; p is 2, 3, or 4; and p′ is 2 or 3.

14. The electrochemical device of claim 1 , wherein the poly(alkyleneoxide) siloxane is 2,2-dimethyl-3,6,9-trioxa-2-siladecane (CH 3 (OCH 2 CH 2 ) 2 OSi(CH 3 ) 3 ) or is:

wherein: p is 2, 3, or 4, and q is 1.

15. The electrochemical device of claim 1 , wherein the electrolyte further comprises a co-solvent.

16. The electrochemical device of claim 15 , wherein the co-solvent comprises ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, fluorinated carbonate, 1,3-dioxolane (“DOL”), dimethoxyethane (“DME”), di(ethylene glycol) dimethyl ether, tri(ethylene glycol) dimethyl ether, tetra(ethylene glycol) dimethyl ether (“TEGDME”), 1,4-dioxane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether; 1,1,2,2-tetrafluoroethyl-2,2,3,3,3-pentafluoropropyl ether; 2,2,2-trisfluoroethyl-1,1,2,3,3,3-hexafluoropropyl ether; ethyl-1,1,2,3,3,3-hexafluoropropyl ether; difluoromethyl-2,2,3,3,3-pentafluoropropyl ether; difluoromethyl-2,2,3,3-tetrafluoropropyl ether; 2-fluoro-1,3-dioxolane; 2,2-difluoro-1,3-dioxolane; 2-trifluoromethyl-1,3-dioxolane; 2,2-bis(trifluoromethyl)-1,3-dioxolane; 4-fluoro-1,3-dioxolane; 4,5-difluoro-1,3-dioxolane, dimethyl sulfoxide, sulfone, tetrahydrofuran, ionic liquids, or a mixture of any two or more thereof.

17. The electrochemical device of claim 1 that is a lithium battery and the salt is LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiB(C 2 O 4 ) 2 (“LiBOB”), LiBF 2 (C 2 O 4 ) (“LiODFB”), LiCF 3 SO 3 , LiN(SO 2 F) 2 (“LiFSI”), LiPF 3 (C 2 F 5 ) 3 (“LiFAP”), LiPF 4 (CF 3 ) 2 , LiPF 3 (CF 3 ) 3 , LiN(SO 2 CF 3 ), LiCF 3 CO 2 , LiC 2 F 5 CO 2 , LiPF 2 (C 2 O 4 ) 2 , LiPF 4 C 2 O 4 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiN(SO 2 C 2 F 5 ) 2 , lithium alkyl fluorophosphates, Li(C 2 O 4 ) 2 , LiBF 2 C 2 O 4 , Li 2 B 12 X 12-p H p , Li 2 B 10 X 10-y H y , or a mixture of any two or more thereof.

18. The electrochemical device of claim 1 that is a sodium battery, wherein the salt is NaClO 4 , NaPF 6 , NaAsF 6 , NaSbF 6 , NaAlCl 4 , NaBF 4 , NaCF 3 SO 3 , NaN(SO 2 CF 3 ) 2 , or a mixture of any two or more thereof.

19. The electrochemical device of claim 1 , wherein the concentration of the salt in the electrolyte is from about 2.5 M to 10 M, and the molarity is determined as moles of salt divided by the volume of the electrolyte, without considering the volume change of the electrolyte composition due to dissolution of the salt.

20. The electrochemical device of claim 1 , wherein the concentration of the salt in the electrolyte is from about 3 M to 10 M, and the molarity is determined as moles of salt divided by the volume of the electrolyte, without considering the volume change of the electrolyte composition due to dissolution of the salt.