Separator having an inorganic layer including a low-density binder with improved adhesive force for secondary batteries
A separator for a secondary battery having improved force of binding to an electrode, and more particularly a separator for a secondary battery including a porous polymer separator substrate and an inorganic layer on at least one surface of the separator substrate. The inorganic layer includes an inorganic material particles and a binder. The binder is a hollow type binder.
1 . A separator for a secondary battery, the separator comprising
a porous polymer separator substrate; and
an inorganic layer on at least one surface of the separator substrate,
wherein the inorganic layer comprises inorganic material particles and a binder, and
wherein the binder is a hollow binder having a density of less than 0.9 g/mL.
2 . The separator according to claim 1 ,
wherein the hollow binder has a particle form, and has a particle size of 550 pm or less.
3 . The separator according to claim 1 , wherein a percentage of the binder present in the inorganic layer is 20 weight % or less.
4 . The separator according to claim 1 , wherein the density of the hollow binder is 0.8453 g/mL or less.
5 . The separator according to claim 1 , wherein the density of the hollow binder is in a range of 0.7268 g/mL to 0.8453 g/mL.
6 . The separator according to claim 1 , wherein the acrylic-containing binder comprises acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile.
7 . The separator according to claim 1 , wherein the hollow binder is an aqueous emulsion binder.
8 . The separator according to claim 7 , wherein the aqueous emulsion binder is an acrylic-containing binder.
9 . The separator according to claim 8 , wherein the acrylic-containing binder is at least one selected from a group consisting of acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile.
10 . A battery cell, comprising an electrode assembly comprising the separator for the secondary battery according to claim 1 interposed between a positive electrode and a negative electrode.
11 . A method of manufacturing the separator for a secondary battery according to claim 1 , the method comprising:
(S 1 ) manufacturing a slurry having a weight ratio of an organic material to the hollow binder of 8:2 and an amount of solids in the slurry is 30% by weight;
(S 2 ) fixing the separator substrate using a bar coater;
(S 3 ) applying the slurry manufactured in step (S 1 ) to at least one edge of the separator substrate in a straight line using a pipette;
(S 4 ) operating a bar to coat the slurry on the at least one edge of the separator substrate; and
(S 5 ) drying the coated slurry.
12 . The method according to claim 11 , wherein the hollow binder has a particle form, and has a particle size of 550 μm or less.
13 . The method according to claim 11 , wherein the hollow binder is at least one selected from a group consisting of acrylamide, ethylene glycol dimethacrylate, and azobisisobutyronitrile.
14 . The method according to claim 11 , further comprising manufacturing the hollow binder before step (S 1 ).