Complex separator for electrochemical element, comprising bonding layer, and electrochemical element comprising same
View Patent ↗The present disclosure relates to a composite separator for an electrochemical element and the electrochemical element including the same. More specifically, the present disclosure relates to a separator with excellent durability and improved formation of a bonding layer of a thin film and improved bonding force with an electrode, and a method for manufacturing the same. Further, the present disclosure pertains to an electrochemical element comprising the aforementioned separator.
1. A composite separator for electrochemical element, the separator comprising:
a porous polymeric material; and
a porous coating layer formed on at least one side surface of the porous polymeric material,
wherein the composite separator includes an electrode bonding layer formed on both surfaces or on at least one surface of outermost surfaces thereof,
the porous coating layer includes inorganic particles and binder resin, an entirety or portion of a surface of the inorganic particles being coated with the binder resin, and thus the particles are laminated by point binding and/or plane binding between the inorganic particles and stratified,
the porous coating layer has a porous structure formed by interstitial volume between the inorganic particles, and
the electrode bonding layer includes a particulate polymer having adhesive characteristics, and glass transition temperature of the particulate polymer is −110° C. to 0° C.,
wherein a melting temperature of the particulate polymer is 20° C. to 150° C.,
wherein the particulate polymer includes a homopolymer of vinylidene fluoride monomer and/or a copolymer of vinylidene fluoride monomer and a co-monomer,
wherein the copolymer is a copolymer resin of (a) vinylidene fluoride monomer and (b) one or more co-monomers selected from a group consisting of vinyl fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethyl ene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl)ether; perfluoro(1,3-dioxole); and perfluoro(2,2-dimethyl-1,3-dioxole)(PDD), and
wherein vinylidene fluoride copolymer comprises vinylidene fluoride monomer in the range of 70 parts by weight to 97 parts by weight with a weight ratio.
2. The composite separator of claim 1 , wherein the bonding layer comprises the particulate polymer including methacrylate polymer.
3. The composite separator of claim 1 , wherein the binder resin is an organic solvent-soluble binder.
4. The composite separator of claim 1 , wherein the inorganic particle does not occur oxidation and/or reduction reaction at an operating voltage range of 0 to 5 V(Li/Li + ) of the electrochemical element.
5. The composite separator of claim 4 , wherein the inorganic particle includes the inorganic particle having ion transfer capabilities and/or a high dielectricity inorganic particle having a dielectric constant of 5 or above.
6. The composite separator of claim 3 , wherein the binder resin is prepared from an organic solvent as a solvent, and the particulate polymer is prepared from a water-borne solvent as a disperse medium.
7. A method for manufacturing a composite separator for electrochemical element according to claim 1 , the method comprising:
applying a slurry including inorganic particles and binder resin of an organic solvent to a porous material and drying it to form a porous coating layer; and
applying a composition for forming an electrode bonding layer containing a particulate polymer on the porous coating layer and drying it to form a bonding layer, and
wherein the composition for forming the electrode bonding layer has a particulate polymer prepared from emulsion or suspension dispersed in a water-borne solvent.
8. The method of claim 7 , wherein the organic solvent is one or two or more types of mixture selected from aliphatic hydrocarbons, aromatic hydrocarbons, ketones, chlorine-based aliphatic hydrocarbons, esters, ethers, alcohols and amides.
9. The composite separator of claim 1 , wherein the electrode bonding layer is formed on an upper surface of the porous coating layer.
10. The composite separator of claim 1 , wherein the electrode bonding layer has a coating amount of the particulate polymer of 0.05 g/m 2 to 5 g/m 2 .
11. A composite separator for electrochemical element, the separator comprising:
a porous polymeric material; and
a porous coating layer formed on at least one side surface of the porous polymeric material,
wherein the composite separator includes an electrode bonding layer formed on both surfaces or on at least one surface of outermost surfaces thereof,
the porous coating layer includes inorganic particles and binder resin, an entirety or portion of a surface of the inorganic particles being coated with the binder resin, and thus the particles are laminated by point binding and/or plane binding between the inorganic particles and stratified,
the porous coating layer has a porous structure formed by interstitial volume between the inorganic particles, and
the electrode bonding layer consists of a particulate polymer having adhesive characteristics, and glass transition temperature of the particulate polymer is −110° C. to 0° C.,
wherein the particulate polymer comprises:
polyvinylidene fluoride (PVDF) homopolymer having vinylidene fluoride (VDF) monomer and/or PVDF based copolymer having VDF monomer and co-monomer; and/or
PVDF homopolymer having VDF monomer and/or methacrylate-based polymer and PVDF based copolymer having VDF monomer and co-monomer; and
wherein the binder resin is prepared in an organic solvent, and the particulate polymer is prepared in an aqueous solvent as a dispersion media, and the binder resin is soluble in organic solvents, and
wherein the PVDF based copolymer and/or PVDF homopolymer having VDF monomer and co-monomer includes vinylidene fluoride and co-monomer in the ratio of 70:30 to 96:4 based on parts by weight.