Abstract:
A polyolefin separator having an heat-resistant ultrafine fibrous layer and a secondary battery using the same, in which the separator has a shutdown function, low thermal contraction characteristics, thermal endurance, excellent ionic conductivity, excellent cycling characteristics at the time of battery construction, and excellent adhesion with an electrode. The present invention adopts a very simple and easy process to form an ultrafine fibrous layer through an electrospinning process, and at the same time, to remove solvent and to form pores. Accordingly, the separator of the present invention is useful particularly for electrochemical devices used in a hybrid electric automobile, an electric automobile, and a fuel cell automobile, requiring high thermal endurance and thermal stability.