FLUORINE-CONTAINING COPOLYMER AND SECONDARY BATTERY COMPRISING THE SAME
A fluorine-containing copolymer has a weight average molecular weight of 600,000 to 2,000,000, and is represented by following formula: One of R 1 and R 2 is H, or unsubstituted or non-perfluoro-substituted C1-C8 linear or branched alkyl, and the other is H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine. R 3 and R 4 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine. R 5 -R 7 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine. R 8 is perfluoro-substituted C1-C8 linear or branched alkyl. m, n, and q are molar proportions of respective repeating units in the fluorine-containing copolymer. M≥90%, 0<n<100%, and 0<q<100%.
1 . A fluorine-containing copolymer having a weight average molecular weight of 600,000 to 2,000,000 and represented by following formula:
wherein:
one of R 1 and R 2 is one selected from H and unsubstituted or non-perfluoro-substituted C1-C8 linear or branched alkyl, and another one of R 1 and R 2 is H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 3 and R 4 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 5 -R 7 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 8 is one of perfluoro-substituted C1-C8 linear or branched alkyl; and
m, n, and q are molar proportions of respective repeating units in the fluorine-containing copolymer, m≥90%, 0<n<100%, and 0<q<100%.
2 . The fluorine-containing copolymer according to claim 1 , wherein m+n=90%-99.9% and q=0.1%-10%;
3 . The fluorine-containing copolymer according to claim 1 , wherein m+n=95%-99.5% and q=0.5%-5%.
4 . The fluorine-containing copolymer according to claim 1 , wherein R 5 -R 7 are each F and R 8 is trifluoromethyl or pentafluoroethyl.
5 . The fluorine-containing copolymer according to claim 1 , wherein the fluorine-containing copolymer has a weight average molecular weight of 800,000 to 1,500,000.
6 . The fluorine-containing copolymer according to claim 1 , wherein the fluorine-containing copolymer is selected from:
7 . A positive electrode slurry comprising:
a positive electrode material; and
a binder comprising a fluorine-containing copolymer having a weight average molecular weight of 600,000 to 2,000,000 and represented by following formula:
wherein:
one of R 1 and R 2 is one selected from H and unsubstituted or non-perfluoro-substituted C1-C8 linear or branched alkyl, and another one of R 1 and R 2 is H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 3 and R 4 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 5 -R 7 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 8 is one of perfluoro-substituted C1-C8 linear or branched alkyl; and
m, n, and q are molar proportions of respective repeating units in the fluorine-containing copolymer, m≥90%, 0<n<100%, and 0<q<100%.
8 . The positive electrode slurry according to claim 7 , wherein the positive electrode material comprises a carbon-coated lithium-containing phosphate material.
9 . The positive electrode slurry according to claim 8 , wherein the positive electrode material further comprises a lithium supplement, and a pH value of the lithium supplement is greater than or equal to 10.0.
10 . The positive electrode slurry according to claim 9 , wherein the lithium supplement comprises at least one selected from Li 2 C 2 , Li 3 N, Li 2 S, Li 6 CoO 4 , Li 5 FeO 4 , Li 3 VO 4 , Li 2 MoO 3 , Li 2 RuO 3 , Li 2 MnO 2 , Li 2 NiO 2 , and Li 2 Cu x N 1-x M y O 2 , where 0<x≤1 and 0≤y<0.1, and M is at least one selected from Zn, Sn, Mg, Fe, and Mn.
11 . The positive electrode slurry according to claim 8 , wherein:
the carbon-coated lithium-containing phosphate material is a first positive electrode active material;
the positive electrode material further comprises a second positive electrode active material represented by following general formula:
Li 1+a [Ni x Co y Mn z M b ]O 2 ,
where 0.6<x<1, 0≤y<0.3, 0≤z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M is one or more selected from Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo, and B; and
a pH value of the second positive electrode active material is greater than or equal to 10.0.
12 . The positive electrode slurry according to claim 11 , wherein the positive electrode material further comprises a lithium supplement.
13 . The positive electrode slurry according to claim 8 , wherein:
the positive electrode material comprises a positive electrode active material represented by following general formula:
Li 1+a [Ni x Co y Mn z M b ]O 2 ,
where 0.8<x<1, 0≤y<0.3, 0≤z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M is one or more selected from Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo, and B; and
a pH value of the positive electrode material is greater than or equal to 10.0.
14 . The positive electrode slurry according to claim 8 , wherein the carbon-coated lithium-containing phosphate material has a volume average particle size Dv50 of 2 μm or less.
15 . The positive electrode slurry according to claim 7 , wherein:
the positive electrode material comprises a positive electrode active material represented by following general formula:
Li 1+a [Ni x Co y Mn z M b ]O 2 ,
where 0.6<x<1, 0≤y<0.3, 0≤z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M is one or more selected from Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo, and B, optionally, 0.8<x<1; and
a pH value of the positive electrode material is greater than or equal to 10.0.
16 . The positive electrode slurry according to claim 15 , wherein the positive electrode material further comprises a lithium supplement.
17 . A secondary battery comprising:
a positive electrode sheet having a positive electrode active material layer obtained by coating and drying a positive electrode slurry comprising:
a positive electrode material; and
a binder comprising a fluorine-containing copolymer having a weight average molecular weight of 600,000 to 2,000,000 and represented by following formula:
wherein:
one of R 1 and R 2 is one selected from H and unsubstituted or non-perfluoro-substituted C1-C8 linear or branched alkyl, and another one of R 1 and R 2 is H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 3 and R 4 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 5 -R 7 are each independently selected from H, F, or C1-C8 linear or branched alkyl substituted or unsubstituted with fluorine;
R 8 is one of perfluoro-substituted C1-C8 linear or branched alkyl; and
m, n, and q are molar proportions of respective repeating units in the fluorine-containing copolymer, m≥90%, 0<n<100%, and 0<q<100%.
18 . A battery module, comprising the secondary battery according to claim 17 .
19 . A battery pack, comprising the battery module according to claim 18 .
20 . An electrical apparatus, comprising the secondary battery according to claim 18 .