Polyolefin microporous film and its manufacture method, and spacer for battery and battery

Abstract

A polyolefin porous membrane is characterized by comprising a polyethylene resin, and is further characterized in that (a) the shutdown temperature is 135 DEG C or lower which is the temperature at which the gas permeability as measured with heating at a heating rate of 5 DEG C / min reaches 1*10<5> sec / 100 cm<3>, (b) the change rate of the gas permeability is 1*10<4> sec / 100 cm<3> or more, the change rate of the gas permeability is the gradient at the coordinate on the curve representing the dependency of the gas permeability to the temperature when the gas permeability is 1*10<4> sec / 100 cm<3>, (c) the transverse shrinkage factor measured at 130 DEG C through the analysis of heating mechanism at a load of 2gf and a heating rate of 5 DEG C / min is 20% or below.

Description

Polyolefin microporous film, method for producing same, separator for battery, and battery technical field The present invention relates to a polyolefin microporous film, a method for producing the same, a separator for a battery, and a battery, and particularly relates to the stability of physical properties up to the start of shutdown, the high rate of change in air permeability after the start of shutdown, and the stability from the shutdown start temperature to the shutdown temperature. A polyolefin microporous film excellent in heat shrinkage resistance in a temperature range and having a low shutdown temperature, a method for producing the same, a separator for a battery, and a battery. Background technique Polyethylene microporous membranes are mainly used as separators for batteries. Especially for separators for lithium-ion batteries, not only excellent mechanical properties and permeability are required, but also the following properties are required: the battery ...

AI Technical Summary

Problems solved by technology

However, in the case of causing a runaway reaction of the battery, if the separator shrinks in the temperature range from the start of the shutdown to the end of the shutdown, a short circuit occurs at its end, and as a result, the runaway reaction is accelerated.

However, the microporous membranes described in each of the above-mentioned documents are insufficient in the ability to maintain the shape and prevent short circuits (heat shrinkage resistance) in the temperature range from the shutdown start temperature to the shutdown temperature.

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