| 摘要 |
<p>A microporous polymeric film comprises a halopolymer in which the repeating units are -(CnH2n)- and -(CmX2m)- in which each X independently represents fluorine or chlorine and the values of n and m are greater than one and less than six. The film is the result of firstly melt processing a mixture of the halopolymer, an extractable salt and extractable polymer secondly extracting at least some of the extractable salt to render the film porous and extracting at least some of said polymer to impart surface porosity to the film. The film may be used as the separator of an electrochemical cell e.g. a battery having a lithium anode and a thionyl chloride electrolyte. High porosities and good electrical properties can be obtained by using as extractable polymer a material having a molecular weight less than one million e.g. a polyethylene oxide of molecular weight about 100,000 - 300,000. The film may be made in relatively long lengths by addition of an anti-oxidant to the mixture to be melt processed.</p> |
