Separator and electrochemical device comprising same
A separator which includes: a porous polymer substrate having a plurality of pores; a separator base including a porous coating layer formed on at least one surface of the porous polymer substrate; and an adhesive layer formed on at least one surface of the separator base, said adhesive layer comprising a plurality of second inorganic particles and adhesive resin particles, wherein the weight ratio of the second inorganic particles to the adhesive resin particles is 5:95-60:40, and the diameter of the adhesive resin particles is 1.1-3.5 times the diameter of the second inorganic particles. An electrochemical device including the separator is also disclosed. The separator shows improved adhesion between an electrode and the separator, maintains the pores of the adhesive layer even after a process of electrode lamination, and improves the resistance of an electrochemical device.
1. A separator comprising:
a porous polymer substrate having a plurality of pores;
a separator base formed on at least one surface of the porous polymer substrate, said separator base comprising a porous coating layer comprising a plurality of first inorganic particles and a binder polymer positioned on a whole or a part of a surface of the first inorganic particles to connect and fix the first inorganic particles with each other; and
an adhesive layer formed on at least one surface of the separator base, said adhesive layer comprising a plurality of second inorganic particles and adhesive resin particles,
wherein a weight ratio of the second inorganic particles to the adhesive resin particles is 5:95-60:40, and
a diameter of the adhesive resin particles is 1.2-1.3 times a diameter of the second inorganic particles.
2. The separator according to claim 1 , wherein the second inorganic particles have an average particle diameter of 100 nm to 700 nm.
3. The separator according to claim 1 , wherein a weight ratio of the first inorganic particles to the binder polymer is 90:10-99:1.
4. The separator according to claim 1 , wherein the weight ratio of the second inorganic particles to the adhesive resin particles is 10:90-50:50.
5. The separator according to claim 1 , wherein the binder polymer is any one selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polymethyl methacrylate-co-ethylhexyl acrylate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalchol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan and carboxymethyl cellulose, or a combination of two or more of them.
6. The separator according to claim 1 , wherein the adhesive resin particle is any one selected from the group consisting of styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, polybutyl acrylate-co-methyl methacrylate, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, polyvinylalcohol, styrene and polycyanoacrylate or a combination of two or more of them.
7. The separator according to claim 1 , wherein the porous coating layer has a thickness of 1 μm to 10 μm and the adhesive layer has a thickness of 0.5 μm to 4 μm.
8. The separator according to claim 1 , wherein the porous polymer substrate is a polyolefin-based porous polymer substrate.
9. An electrochemical device comprising:
a cathode;
an anode; and
a separator interposed between the cathode and the anode,
wherein the separator is the separator as defined in claim 1 .
10. The electrochemical device according to claim 9 , wherein the electrochemical device is a lithium secondary battery.