ELECTROCHEMICAL CELLS WITH IONIC LIQUID ELECTROLYTE
The present invention provides a lithium-ion electrochemical cell comprising an ionic liquid electrolyte solution and a positive electrode having a carbon sheet current collector.
1 . A lithium-ion electrochemical cell comprising:
a positive electrode comprising a positive electrode active material and a free-standing carbon sheet current collector in electronically conductive contact with the positive electrode material, wherein the carbon sheet current collector has a purity of greater than 95% and an in-plane electronic conductivity of at least 1000 S/cm;
a negative electrode comprising a negative electrode active material and a current collector in electronically conductive contact with the negative electrode material;
an ion permeable separator; and
an electrolyte solution in ionically conductive contact with said negative electrode and positive electrode, wherein the electrolyte solution comprises a lithium compound and a solvent selected from an ionic liquid of formula (I) or a mixture of an organic solvent and an ionic liquid of formula (I):
Q + E − (I)
wherein
Q + is a cation selected from the group consisting of dialkylammonium, trialkylammonium, tetraalkylammonium, dialkylphosphonium, trialkylphosphonium, tetraalkylphosphonium, trialkylsulfonium, (R f ) 4 N + and an N-alkyl or N-hydrogen cation of a 5-or 6-membered heterocycloalkyl or heteroaryl ring having from 1-3 heteroatoms as ring members selected from N, O or S, wherein the heterocycloalkyl or heteroaryl ring is optionally substituted with from 1-5 optionally substituted alkyls;
E − is an anion selected from the group consisting of R 1 —X − R 2 (R 3 ) m , NC—S − , BF 4 − , PF 6 − , R a SO 3 − , R a P − F 3 , R a CO 2 − , I − , ClO 4 − , (FSO 2 ) 2 N−, AsF 6 − , SO 4 − and bis[oxalate(2-)-O,O′]borate, wherein
m is 0 or 1;
X is N when m is 0;
X is C when m is 1;
R 1 , R 2 and R 3 are each independently an electron-withdrawing group selected from the group consisting of halogen, —CN, —SO 2 R b , —SO 2 —L a —SO 2 N − Li + SO 2 R b , —P(O)(OR b ) 2 , —P(O)(R b ) 2 , —CO 2 R b , —C(O)R b and —H; with the proviso that R 1 and R 2 are other than hydrogen when m=0, and no more than one of R 1 , R 2 and R 3 is hydrogen when m=1;
each R a is independently C 1-8 perfluoroalkyl;
each R b is independently selected from the group consisting of C 1-8 alkyl, C 1-8 haloalkyl, C 1-8 perfluoroalkyl, perfluorophenyl, aryl, optionally substituted barbituric acid and optionally substituted thiobarbituric acid;
each R f is independently alkyl or alkoxyalkyl; and
wherein at least one carbon-carbon bond of the alkyl or perfluoroalkyl are optionally substituted with a member selected from —O— or —S— to form an ether or a thioether linkage and the aryl is optionally substituted with from 1-5 members selected from the group consisting of halogen, C 1-4 haloalkyl, C 1-4 perfluoroalkyl, —CN, —SO 2 R c , —P(O)(OR c ) 2 , —P(O)(R c ) 2 , —CO 2 R c and —C(O)R c , wherein R c is independently C 1-8 alkyl, C 1-8 perfluoroalkyl or perfluorophenyl and L a is C 1-4 perfluoroalkylene.
2 . The cell of claim 1 , wherein the organic solvent is a carbonate, a lactone or a mixture thereof.
3 . The cell of claim 1 , wherein solvent is a mixture of an organic solvent and an ionic liquid and wherein the organic solvent and the ionic liquid has a volume ratio from about 1:10 to about 10:1 solvent is a mixture of an organic solvent and an ionic liquid.
4 . The cell of claim 1 , wherein the anion is CF 3 SO 2 X − R 2 (R 3 ) m .
5 . The cell of claim 1 , wherein the anion is selected from the group consisting of (CF 3 SO 2 ) 3 C − , (CF 3 SO 2 ) 2 CH − , CF 3 (CH 2 ) 3 SO 3 − , (CH 3 SO 2 ) 2 N − , (CN) 2 N − , SO 4 − , CF 3 SO 3 − , NC—S − , BF 4 − , PF 6 − , ClO 4 − , (CF 3 CF 2 ) 3 P − R 3 , CH 3 CO 2 − , I − , SO 4 − and bis[oxalate(2-)-O,O′]borate.
6 . The cell of claim 1 , wherein the positive electrode active material comprises phosphates, sulfates or a lithium insertion transition metal oxide selected from the group consisting of LiCoO 2 , spinel LiMn 2 O 4 , chromium-doped spinel lithium manganese oxide, layered LiMnO 2 , LiNiO 2 , LiNi x Co 1−x O 2 , vanadium oxide, LiFePO 4 , LiFeTi(SO 4 ) 3 , Li 1+x A y M 2−y O 4 and LiMXO 4 ,
wherein:
the subscript x is a real number between about 0 and 1;
the subscript y is a real number between about 0 and 1;
M and A are each independently Fe, Mn, Co, Ni or a combination thereof; and
X is P, V, S, Si or a combination thereof.
7 . The cell of claim 6 , wherein the positive electrode active material comprises LiNi 0.5 Mn 1.5 O 4 .
8 . The cell of claim 1 , wherein the negative electrode active material comprises lithium-intercalated carbon, lithium metal nitride, metallic lithium alloy, metal oxide, carbon microbeads, a natural graphite, a carbon fiber, a graphite microbead, a carbon nanotube, hard carbon or a graphite flake or a combination thereof.
9 . The cell of any of claim 1 , wherein the current collector is a conductive carbon sheet selected from the group consisting of a graphite sheet, a carbon fiber sheet, a carbon foam and a carbon nanotube film and/or a mixture thereof.
10 . The cell of claim 9 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 2000 S/cm.
11 . The cell of claim 9 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 3000 S/cm.
12 . The cell of claim 1 , wherein the lithium compound has formula: Li + E − .
13 . The cell of claim 12 , wherein the lithium compound is LiPF 6 , LiBF 4 , LiClO 4 , (FSO 2 ) 2 N − Li + or AsF 6 − .
14 . The cell of claim 1 , wherein the lithium compound has formula (II):
R 1 —X − (Li + )R 2 (R 3 ) n II
wherein:
n is 0 or 1;
X is N when n is 0;
X is C when n is 1;
R 1 , R 2 and R 3 are each independently an electron-withdrawing group selected from the group consisting of halogen, —CN, —SO 2 R b , —SO 2 (—R b —SO 2 Li + )SO 2 —R b , —P(O)(OR b ) 2 , —P(O)(R b ) 2 , —CO 2 R b , —C(O)R b and —H; with the proviso that R 1 and R 2 are other than hydrogen when n=0, and no more than one of R 1 , R 2 and R 3 is hydrogen when n=1; and
wherein each R b is independently selected from the group consisting of C 1-8 alkyl, C 1-8 haloalkyl, C 1-8 perfluoroalkyl, perfluorophenyl, aryl, optionally substituted barbituric acid and optionally substituted thiobarbituric acid, wherein at least one carbon-carbon bond of the alkyl or perfluoroalkyl are optionally substituted with a member selected from —O— or —S— to form an ether or a thioether linkage and the aryl is optionally substituted with from 1-5 members selected from the group consisting of halogen, C 1-4 haloalkyl, C 1-4 perfluoroalkyl, —CN, —SO 2 R c , —P(O)(OR c ) 2 , —P(O)(R c ) 2 , —CO 2 R c and —C(O)R c , wherein R c is C 1-8 alkyl, perfluorophenyl or C 1-8 perfluoroalkyl, wherein the compound has an oxidation potential above the recharged potential of the positive electrode.
15 . The cell of claim 14 , wherein the lithium compound having the formula: CF 3 SO 2 N − (Li + )SO 2 CF 3 .
16 . The cell of claim 1 , wherein Q + is a cation having formula (Ia):
wherein
R 4 is —H, C 1-20 alkyl or C 1-20 alkoxyalkyl, optionally substituted with from 1-3 members selected from the group consisting of halogen and C 1-4 perfluoroalkyl;
Y 1 and Y 3 are each independently selected from the group consisting of ═N— and ═CR d —;
Y 2 and Y 4 are each independently selected from the group consisting of ═N—, —O—, —S—, —NR d — and ═CR d —, with the proviso that Y 2 and Y 4 are not simultaneously a member selected from the group consisting of —NR d — and ═CR d —, or simultaneously a member selected from the group consisting of —O—, —NR d — and —S—;
wherein each R d is independently —H, alkyl or alkoxyalkyl.
17 . The cell of claim 16 , wherein Q + is a cation having formula Ia-1:
18 . The cell of claim 17 , wherein Y 1 is ═N— or ═CR d —.
19 . The cell of claim 18 , wherein Y 1 is ═CR d —.
20 . The cell of claim 17 , wherein Y 4 is —O—.
21 . (canceled)
22 . The cell of claim 17 , wherein Y 1 , Y 3 and Y 4 are ═CH—, R 4 is methyl and R d is C 1-8 alkyl or C 1-8 alkoxyalkyl.
23 . The cell of claim 1 , wherein Q + is a cation having formula (Ib):
wherein
R 5 is —H, alkoxyalkyl or C 1-20 alkyl, optionally substituted with from 1-3 members selected from the group consisting of halogen and C 1-4 perfluoroalkyl; and
Z 1 , Z 2 , Z 3 , Z 4 and Z 5 are each independently selected from the group consisting of ═N— and ═CR e —, wherein each R e is independently selected from the group consisting of —H, alkyl and alkoxyalkyl, or optionally the R e substituents on the adjacent carbons are combined with the atoms to which they are attached form a 5- or 6-membered ring having from 0-2 addition heteroatoms as ring members selected from O, N or S.
24 . The cell of claim 23 , wherein Z 1 is ═N—.
25 . The cell of claim 24 , wherein Z 2 , Z 3 , Z 4 and Z 5 are ═CR e —.
26 . The cell of claim 23 , wherein Z 2 is ═N—.
27 . The cell of claim 26 , wherein Z 1 , Z 3 , Z 4 and Z 5 are ═CR e —.
28 . The cell of claim 23 , wherein Z 3 is ═N—.
29 . The cell of claim 28 , wherein Z 1 , Z 2 , Z 4 and Z 5 are ═CR e —.
30 . (canceled)
31 . The cell of claim 1 , wherein Q + is a cation having formula (Ic):
wherein
the subscript p is 1 or 2; and
R 6 and R 7 are each independently H or an optionally substituted C 1-8 alkyl.
32 . The cell of claim 31 , wherein p is 1 and R 6 and R 7 are each independently an optionally substituted C 1-8 alkyl.
33 . The cell of claim 32 , wherein R 6 and R 7 are each independently a C 1-8 alkyl.
34 . The cell of claim 33 , wherein p is 1, R 6 is methyl and R 7 is C 1-8 alkyl.
35 . (canceled)
36 . A battery pack comprising a plurality of cells, wherein each cell comprises:
an ionic liquid of formula (I):
Q + E −(I)
wherein
Q + is a cation selected from the group consisting of dialkylammonium, trialkylammonium, tetraalkylammonium, dialkylphosphonium, trialkylphosphonium, tetraalkylphosphonium, trialkylsulfonium, (R f ) 4 N + and an N-alkyl or N-hydrogen cation of a 5- or 6-membered heterocycloalkyl or heteroaryl ring having from 1-3 heteroatoms as ring members selected from N, O or S, wherein the heterocycloalkyl or heteroaryl ring is optionally substituted with from 1-5 optionally substituted alkyls;
E − is an anion selected from the group consisting of R 1 —X − R 2 (R 3 ) m , NC—S − , BF 4 − , PF 6 − , R a SO 3 − , R a P − F 3 , R a CO 2 − , I − , ClO 4 − , (FSO 2 ) 2 N—, AsF 6 − , SO 4 − and bis[oxalate(2-)O,O′]borate, wherein
m is 0 or 1;
X is N when m is 0;
X is C when m is 1;
R 1 , R 2 and R 3 are each independently an electron-withdrawing group selected from the group consisting of halogen, —CN, —SO 2 R b , —SO 2 -L a -SO 2 N − Li + SO 2 R b , —P(O)(OR b ) 2 , —P(O)(R b ) 2 , —CO 2 R b , —C(O)R b and —H; with the proviso that R 1 and R 2 are other than hydrogen when m=0, and no more than one of R 1 , R 2 and R 3 is hydrogen when m=1;
each R a is independently C 1-8 perfluoroalkyl;
each R b is independently selected from the group consisting of C 1-8 alkyl, C 1-8 haloalkyl, C 1-8 perfluoroalkyl, perfluorophenyl, aryl, optionally substituted barbituric acid and optionally substituted thiobarbituric acid;
each R f is independently alkyl or alkoxyalkyl; and
wherein at least one carbon-carbon bond of the alkyl or perfluoroalkyl are optionally substituted with a member selected from —O— or —S— to form an ether or a thioether linkage and the aryl is optionally substituted with from 1-5 members selected from the group consisting of halogen, C 1-4 haloalkyl, C 1-4 perfluoroalkyl, —CN, —SO 2 R c , —P(O)(OR c ) 2 , —P(O)(R c ) 2 , —CO 2 R c and —C(O)R c , wherein R c is independently C 1-8 alkyl, C 1-8 perfluoroalkyl or perfluorophenyl and L a is C 1-4 perfluoroalkylene; and
a positive electrode comprising a positive electrode active material and a free-standing carbon sheet current collector in electronically conductive contact with the positive electrode material, wherein the carbon sheet current collector has a purity of greater than 95% and an in-plane electronic conductivity of at least 1000 S/cm.
37 . A lithium-ion electrochemical cell comprising:
a positive electrode comprising a positive electrode active material and a free-standing carbon sheet current collector in electronically conductive contact with the positive electrode material, wherein the carbon sheet current collector has a purity of greater than 95% and an in-plane electronic conductivity of at least 1000 S/cm;
a negative electrode comprising a negative electrode active material and a current collector in electronically conductive contact with the negative electrode material;
at least one positive electrode tab having a first attachment end and a second attachment end, wherein the first attachment end of said at least one positive electrode tab is connected to said positive electrode carbon sheet current collector;
at least one negative electrode tab having a first attachment end and a second attachment end, wherein said first attachment end of said at least one negative electrode tab is connected to said negative electrode current collector;
an ion permeable separator; and
an electrolyte solution in ionically conductive contact with said negative electrode and positive electrode, wherein the electrolyte solution comprises a lithium compound and a solvent selected from an ionic liquid of formula (I) or a mixture of an organic solvent and an ionic liquid of formula (I):
Q + E − (I)
wherein
Q + is a cation selected from the group consisting of dialkylammonium, trialkylammonium, tetraalkylammonium, dialkylphosphonium, trialkylphosphonium, tetraalkylphosphonium, trialkylsulfonium, (R f ) 4 N + and an N-alkyl or N-hydrogen cation of a 5- or 6-membered heterocycloalkyl or heteroaryl ring having from 1-3 heteroatoms as ring members selected from N, O or S, wherein the heterocycloalkyl or heteroaryl ring is optionally substituted with from 1-5 optionally substituted alkyls;
E − is an anion selected from the group consisting of R 1 —X − R 2 (R 3 ) m , NC—S − , BF 4 − , PF 6 − , R a SO 3 − , R a P − F 3 , R a CO 2 − , I − , ClO 4 − , (FSO 2 ) 2 N—, AsF 6 − , SO 4 − and bis[oxalate(2-)-O,O′]borate, wherein
m is 0 or 1;
X is N when m is 0;
X is C when m is 1;
R 1 , R 2 and R 3 are each independently an electron-withdrawing group selected from the group consisting of halogen, —CN, —SO 2 R b , —SO 2 -L a -SO 2 N − Li + SO 2 R b , —P(O)(OR b ) 2 , —P(O)(R b ) 2 , —CO 2 R b , —C(O)R b and —H; with the proviso that R 1 and R 2 are other than hydrogen when m=0, and no more than one of R 1 , R 2 and R 3 is hydrogen when m=1;
each R a is independently C 1-8 perfluoroalkyl;
each R b is independently selected from the group consisting of C 1-8 alkyl, C 1-8 haloalkyl, C 1-8 perfluoroalkyl, perfluorophenyl, aryl, optionally substituted barbituric acid and optionally substituted thiobarbituric acid;
each R f is independently alkyl or alkoxyalkyl; and
wherein at least one carbon-carbon bond of the alkyl or perfluoroalkyl are optionally substituted with a member selected from —O— or —S— to form an ether or a thioether linkage and the aryl is optionally substituted with from 1-5 members selected from the group consisting of halogen, C 1-4 haloalkyl, C 1-4 perfluoroalkyl, —CN, —SO 2 R c , —P(O)(OR c ) 2 , —P(O)(OR c ) 2 , —P(O)(R c ) 2 , —CO 2 R c and —C(O)R c , wherein R c is independently C 1-8 alkyl, C 1-8 perfluoroalkyl or perfluorophenyl and L a is C 1-4 perfluoroalkylene.
38 . The cell of claim 37 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 2000 S/cm.
39 . The cell of claim 37 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 3000 S/cm.