Binder, separator, and lithium-ion battery using such separator
This application relates to the field of lithium battery technologies, and in particular, to a binder, a separator, and a lithium-ion battery using such separator, where the binder includes a terpolymer formed by copolymerization of a first monomer unit, a second monomer unit, and a third monomer unit that are specified.
1 . A separator comprising a base layer and a binding layer stacked sequentially;
wherein the binding layer comprises a binder,
the binder consisting of a terpolymer, thermally expandable microspheres, and ceramic particles, wherein monomer units of the terpolymer consist of a first monomer unit, a second monomer unit, and a third monomer unit; wherein the first monomer unit is selected from methyl acrylate, n-butyl acrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate; the second monomer unit is selected from at least one of acrylonitrile and methacrylonitrile; the third monomer unit is selected from at least one of acrylamide, N-hydroxymethyl acrylamide, and N-butoxymethyl acrylamide; and a molar ratio of the first monomer unit, the second monomer unit, and the third monomer unit is 50-58:40-44:2-6,
a weight-average molecular weight Mw of the terpolymer is 60000-120000 g/mol;
a mass ratio of the binder, the thermally expandable microspheres, and the ceramic particles in the binding layer is 25-30:10-20:50-65.
2 . The separator according to claim 1 , wherein a glass transition temperature Tg of the terpolymer is −20° C. to 40° C.
3 . The separator according to claim 1 , wherein a glass transition temperature of the thermally expandable microspheres is 40-100° C.
4 . The separator according to claim 3 , wherein a median particle size D v 50 of the thermally expandable microspheres is 0.1 μm-2 μm.
5 . The separator according to claim 1 , wherein the ceramic particles are at least one of alumina, boehmite, silica, and titanium dioxide, with a median particle size D v 50 of 0.5 μm-5 μm.
6 . The separator according to claim 1 , wherein the first monomer unit is methyl acrylate, the second monomer unit is acrylonitrile, the third monomer unit is acrylamide.
7 . The separator according to claim 1 , wherein the first monomer unit is n-butyl acrylate, the second monomer unit is acrylonitrile, the third monomer unit is N-hydroxymethyl acrylamide.
8 . The separator according to claim 1 , wherein the first monomer unit is ethyl methacrylate, the second monomer unit is acrylonitrile, the third monomer unit is N-hydroxymethyl acrylamide.
9 . The separator according to claim 1 , wherein the first monomer unit is 2-hydroxyethyl methacrylate, the second monomer unit is methacrylonitrile, the third monomer unit is N-butoxymethyl acrylamide.
10 . A lithium-ion battery, comprising the separator according to claim 1 .
11 . A battery pack, comprising the lithium-ion battery according to claim 10 .
12 . An electric apparatus, comprising the battery according to claim 11 .