Provided is a composition for a non-aqueous secondary battery porous membrane capable of forming a porous membrane having excellent peel strength and capable of providing a non-aqueous secondary battery having excellent output characteristics. The composition for a non-aqueous secondary battery porous membrane contains inorganic particles, a binder, a surfactant, and water. The binder includes a polymer including an aromatic vinyl monomer unit. Fractional content of the surfactant is not less than 0.25 parts by mass and not more than 5 parts by mass per 100 parts by mass of the inorganic particles.

Provided is a composition for a non-aqueous secondary battery porous membrane capable of forming a porous membrane having excellent peel strength and capable of providing a non-aqueous secondary battery having excellent output characteristics. The composition for a non-aqueous secondary battery porous membrane contains inorganic particles, a binder, a surfactant, and water. The binder includes a polymer including an aromatic vinyl monomer unit. Fractional content of the surfactant is not less than 0.25 parts by mass and not more than 5 parts by mass per 100 parts by mass of the inorganic particles.

A separator for secondary batteries that allows the amount of a dispersing resin that is used and the amount of a dispersant that is used to be reduced in order to prevent an increase in resistance after the separator is coated, which occurs in the case in which a large amount of the dispersing resin is used in order to disperse inorganic matter, and an electrochemical device having the same applied thereto. The amount of a dispersing resin is reduced, whereby it is possible to prevent an increase in resistance after a porous separator is coated, a dispersing resin having a specific weight average molecular weight is mixed, whereby physical properties and dispersivity are improved, and the use of an expensive dispersant is excluded, whereby processing costs are reduced.

The invention relates to an acrylonitrile copolymer binder and application thereof in lithium ion battery, belonging to the field of lithium ion battery. The technical problem to be solved by the invention is to provide an acrylonitrile copolymer binder comprising the following structural units in percentage by weight: 78-95% of acrylonitrile unit, 1-10% of acrylic ester unit and 2-15% of acrylamide unit. For the binder of the invention, acrylonitrile monomer is taken as the main body, and acrylic ester monomer, acrylamide monomer or acrylate salt monomer with strong polarity is added to acrylonitrile for copolymerization to enable the flexibility of a polymer membrane, the affinity of an electrolyte and the proper swelling degree in the electrolyte while keeping strong adhesion or intermolecular force of acrylonitrile polymer molecules, so as to fit the periodic volume changes of electrode active materials along with lithium ion intercalation/deintercalation in charging and discharging processes, thereby improving the energy density and cycle performance of the lithium ion battery.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.

A composite porous membrane contains at least one porous base layer and at least one uniaxially stretched coating layer located on at least one side surface of the porous base layer. For example, the composite porous membrane comprises at least one porous base layer and at least one nanofiber-like non-polyolefin polymer porous layer oriented along the transverse stretching direction of the composite porous membrane and located on one or two side surfaces of the porous base layer, or the composite porous membrane comprises a biaxially stretched polypropylene porous base layer and a uniaxially stretched coating layer located on at least one side surface of the porous base layer. The composite porous membrane is coated with a coating solution prior to transversely stretching. The nanofiber-like non-polyolefin polymer porous layer may reduce cracking of the composite porous membrane in the machine direction.

A porous film has a porous substrate and, on at least one surface of the porous substrate, porous layer that contains particles A. The particles A have a mixture containing a polymer that includes fluorine-containing (meth)acrylate monomers and a polymer that includes monomers having two or more reactive groups per molecule, or the particles A have a copolymer containing fluorine-containing (meth)acrylate monomers and monomers that have two or more reactive groups per molecule. The monomers having two or more reactive groups per molecule are contained in the particles A in an amount ranging from greater than 10% by mass to not more than 30% by mass, where all components of the particles A are assumed to constitute 100% by mass.

A porous film has a porous substrate and, on at least one surface of the porous substrate, porous layer that contains particles A. The particles A have a mixture containing a polymer that includes fluorine-containing (meth)acrylate monomers and a polymer that includes monomers having two or more reactive groups per molecule, or the particles A have a copolymer containing fluorine-containing (meth)acrylate monomers and monomers that have two or more reactive groups per molecule. The monomers having two or more reactive groups per molecule are contained in the particles A in an amount ranging from greater than 10% by mass to not more than 30% by mass, where all components of the particles A are assumed to constitute 100% by mass.

A porous film includes a porous substrate and, on at least one surface of the porous substrate, a porous layer including inorganic particles and organic particles A, the organic particles A having adhesiveness to electrodes. The inorganic particle content in the porous layer is 50% by mass to 95% by mass. In 50 measurements of the surface elastic modulus of the porous layer, the value of α/β is 10 to 40, where α is the surface elastic modulus indicating the inorganic particles, and β is the minimum of the measured values, and the percentage of the 50 measured values that are included in the range from β to 2β is 30% to 100%.

This application relates to a separator with an organic-inorganic hybrid layer. By comprehensively adjusting an adaptive collocation relationship between the median diameter of the first inorganic particles and the median diameter of the second inorganic particles, and by controlling reasonable collocation between the microscale particles and the nanoscale particles, this application develops a separator that is capable of significantly reducing transition metal ions in an electrolytic solution and that is highly ion-permeable, thereby significantly improving the cycle performance and storage performance of lithium-ion batteries.