Abstract: Microporous polyolefin membrane modified by aqueous polymer of the invention is obtained by the following steps: copolymerizing 100 parts of a water-soluble polymer, 30-500 parts of a hydrophobic monomer, 0-200 parts of a hydrophilic monomer and 1-5 parts of an initiator into polymeric colloid emulsion; adding 0-100% of an inorganic filler and 20-100% of a plasticizer based on 100% solid content of the polymeric colloid emulsion to obtain slurry; and coating the slurry on one or two surfaces of the surface modified microporous polyolefin membrane and then drying. The microporous polyolefin membrane modified by aqueous polymer has thermal shutdown effect and little thermal shrinkage, and improves the main problem of shrinkage of the microporous polyolefin membrane at high temperature.

Abstract: Provided are separators used in power accumulators such as lithium ion secondary batteries and a preparation method thereof. The said separators are obtained through following steps: providing a polymer colloidal emulsion through a polymerization reaction of polyvinyl alcohol, hydrophobic monomer and hydrophilic monomer in water solution initiated by an initiator; coating a plastic substrate with the said polymer colloidal emulsion using tape-casting method; drying the plastic substrate coated with the polymer colloidal emulsion, and then obtaining the said separators by delaminating them from the substrate. The said separators have good liquid absorbability, high liquid absorption rate and retention, low resistivity, good mechanical strength and good thermal stability (little thermal shrinkage and little size distortion) as well as electrochemical stability. The prepared lithium ion batteries have good cycle stability and long service life.

Abstract: Microporous polyolefin membrane modified by aqueous polymer of the invention is obtained by the following steps: copolymerizing 100 parts of a water-soluble polymer, 30-500 parts of a hydrophobic monomer, 0-200 parts of a hydrophilic monomer and 1-5 parts of an initiator into polymeric colloid emulsion; adding 0-100% of an inorganic filler and 20-100% of a plasticizer based on 100% solid content of the polymeric colloid emulsion to obtain slurry; and coating the slurry on one or two surfaces of the surface modified microporous polyolefin membrane and then drying. The microporous polyolefin membrane modified by aqueous polymer has thermal shutdown effect and little thermal shrinkage, and improves the main problem of shrinkage of the microporous polyolefin membrane at high temperature.

Abstract: Provided are separators used in power accumulators such as lithium ion secondary batteries and a preparation method thereof. The said separators are obtained through following steps: providing a polymer colloidal emulsion through a polymerization reaction of polyvinyl alcohol, hydrophobic monomer and hydrophilic monomer in water solution initiated by an initiator; coating a plastic substrate with the said polymer colloidal emulsion using tape-casting method; drying the plastic substrate coated with the polymer colloidal emulsion, and then obtaining the said separators by delaminating them from the substrate. The said separators have good liquid absorbability, high liquid absorption rate and retention, low resistivity, good mechanical strength and good thermal stability (little thermal shrinkage and little size distortion) as well as electrochemical stability. The prepared lithium ion batteries have good cycle stability and long service life.