High-strength separator
AssigneeAsahi Kasei Battery Separator Corporation
InventorsXun Zhang, Ryo Kuroki, Yuichiro Ido, Kensuke Niimura, Tomoki Ishikawa
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Abstract
A separator for an electricity storage device has a cross-sectional crystal orientation of 0.85 or greater, and/or a method for producing the separator for an electricity storage device comprises a step of using a continuous mixer under conditions with a temperature of 20° C. to 70° C., a shear rate of 100 to 400,000 seconds−1 and a residence time of 1.0 seconds to 60 seconds, for mixing of polyethylene-containing polyolefin powder with a plasticizer to produce a mixed slurry, a step of extruding the mixed slurry and cooling it to solidification to process it into a cast sheet, and a step of biaxially stretching the cast sheet to an area increase factor of 20 to 200.
Claims18
A method for producing a polyolefin microporous membrane separator for a lithium ion secondary battery, wherein the method comprises the following steps:
- (1) a step of using a continuous mixer under conditions with a temperature of 20° C. to 70° C., a shear rate of 100 seconds−1 to 400,000 seconds−1 and a residence time of 1.0 seconds to 60 seconds, for mixing of a plasticizer with a polyolefin powder containing polyethylene (PE), to obtain a mixed slurry;
- (2) a step of loading the mixed slurry into a twin-screw extruder and extruding the mixed slurry to produce a resin composition;
- (3) a step of extruding the resin composition into a sheet and cooling the sheet to solidification to process the solidification into a cast sheet;
- (4) a step of biaxially stretching the cast sheet in an area increase factor of 20 times to 200 times, to form a stretched sheet;
- (5) a step of extracting the plasticizer from the stretched sheet to form a porous body;
- and
- (6) a step of heat treating the porous body at a temperature below the melting point of the porous body, and stretching the porous body,
- wherein the mixed slurry consists of the polyolefin powder and the plasticizer, and one or more selected from a group consisting of a dehydrating condensation catalyst, a metal soap, an ultraviolet absorbers, a light stabilizer, an antistatic agent, an anti-fogging agent, a color pigment, and an antioxidant, and
- wherein a weight ratio of the polyolefin powder in the mixed slurry is greater than 0 weight % and is 50 weight % or lower based on the weight of the mixed slurry.
A method for producing a polyolefin microporous membrane separator for a lithium ion secondary battery, wherein the method comprises the following steps:
- (1) a step of using a continuous mixer under conditions with a temperature of 20° C. to 70° C., a shear rate of 100 seconds−1 to 400,000 seconds−1 and a residence time of 1.0 seconds to 60 seconds, for mixing of a plasticizer with a polyolefin powder containing polyethylene (PE), to obtain a mixed slurry;
- (2) a step of loading the mixed slurry into a twin-screw extruder and extruding the mixed slurry to produce a resin composition;
- (3) a step of extruding the resin composition into a sheet and cooling the sheet to solidification to process the solidification into a cast sheet;
- (4) a step of biaxially stretching the cast sheet in an area increase factor of 20 times to 200 times, to form a stretched sheet;
- (5) a step of extracting the plasticizer from the stretched sheet to form a porous body;
- and
- (6) a step of heat treating the porous body at a temperature below the melting point of the porous body, and stretching the porous body,
- wherein the mixed slurry consists essentially of the polyolefin powder and the plasticizer, and
- wherein a weight ratio of the polyolefin powder in the mixed slurry is greater than 0 weight % and is 50 weight % or lower.
A method for producing a polyolefin microporous membrane separator for a lithium ion secondary battery, wherein the method comprises the following steps:
- (1) a step of using a continuous mixer under conditions with a temperature of 20° C. to 70° C., a shear rate of 100 seconds−1 to 400,000 seconds−1 and a residence time of 1.0 seconds to 60 seconds, for mixing of a plasticizer with a polyolefin powder containing polyethylene (PE), to obtain a mixed slurry;
- (2) a step of loading the mixed slurry into a twin-screw extruder and extruding the mixed slurry to produce a resin composition;
- (3) a step of extruding the resin composition into a sheet and cooling the sheet to solidification to process the solidification into a cast sheet;
- (4) a step of biaxially stretching the cast sheet in an area increase factor of 20 times to 200 times, to form a stretched sheet;
- (5) a step of extracting the plasticizer from the stretched sheet to form a porous body;
- and
- (6) a step of heat treating the porous body at a temperature below the melting point of the porous body, and stretching the porous body,
- wherein the mixed slurry consists essentially of the polyolefin powder and the plasticizer, and one or more selected from a group consisting of a dehydrating condensation catalyst, a metal soap, an ultraviolet absorbers, a light stabilizer, an antistatic agent, an anti-fogging agent, a color pigment, and an antioxidant, and
- wherein a weight ratio of the polyolefin powder in the mixed slurry is greater than 0 weight % and is 50 weight % or lower.
Dependencies are inferred from the claim text.