Separator having electrode adhesive layer and electrochemical device including the same
Disclosed are a separator having an electrode adhesive layer and an electrochemical device including the same. The electrode adhesive layer includes organic particles and an acrylic resin binder. Preferably, the acrylic resin binder is present in an amount of 30 wt % or more, so that a film-shaped electrode adhesive layer can be formed even when the organic particles have a particle diameter smaller than that of the pores of the underlying substrate or voids of the underlying porous coating layer.
1. A separator for an electrochemical device comprising: a porous polymer substrate; a porous coating layer formed on at least one surface of the porous polymer substrate and including inorganic particles and a binder polymer said porous coating layer being present between the porous polymer substrate and an electrode adhesive layer, which electrode adhesive layer is formed on the outermost surface of the separator and comprises organic particles and a vitrified acrylic resin binder,
wherein vitrified acrylic resin fixes and binds organic particles to form a film-shaped electrode adhesive layer,
wherein the vitrified acrylic resin binder is present in an amount of 30-80 wt % based on a combined weight of the organic particles and vitrified acrylic resin binder,
wherein the vitrified acrylic resin binder is any one or at least two selected from the group consisting of ethyl acrylate-acrylic acid-N,N-dimethylacrylamide copolymer, ethyl acrylate-acrylic acid-2-(dimethylamino)ethyl acrylate copolymer, ethyl acrylate-acrylic acid-N,N-diethylacrylamide copolymer and ethyl acrylate-acrylic acid-2-(diethylamino)ethyl acrylate copolymer,
wherein the organic particles have an average diameter smaller than that of the pores formed in the porous coating layer located directly under the electrode adhesive layer,
wherein the organic particles are not introduced into the pores of the porous coating layer but are located on the surface to form the electrode adhesive layer, and
wherein the electrode adhesive layer has voids formed among the organic particles.
2. The separator for an electrochemical device according to claim 1 , wherein the organic particles are any one or at least two polymers or copolymers selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyethylene-co-vinyl acetate, polyimide and polyethylene oxide.
3. The separator for an electrochemical device according to claim 1 , wherein the organic particles have an average particle diameter of 0.05-0.5 μm.
4. The separator for an electrochemical device according to claim 1 , wherein the vitrified acrylic resin binder has a glass transition temperature of −50 to 60° C.
5. The separator for an electrochemical device according to claim 1 , wherein the electrode adhesive layer is formed in a film shape in at least 20% of the surface area of the separator.
6. The separator for an electrochemical device according to claim 1 , wherein the electrode adhesive layer has a thickness of 0.01-1.0 μm.
7. The separator for an electrochemical device according to claim 1 , wherein the electrode adhesive layer is formed in at least 20% and 80% or less of the surface area of the separator.
8. An electrochemical device comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, wherein the separator is the separator as defined in claim 1 .
9. The electrochemical device according to claim 8 , which is a lithium secondary battery.