We investigate on the technological potential and issues of non-woven separator as an alternative to conventional separator in terms of various evaluation points. Thus, optimal evaluation systems for new nonwoven polyacrylonitrile (PAN) separator are proposed to compare with commercialized polyethylene (PE) separator, and corresponding stacking-type pouch batteries are used as an evaluation tool. Cell performance, electrochemical stability, and thermal stability for both separators are compared. Based on the comparison results, each separator’s effects are discussed in detail. In comparison to PE separator, the non-woven separator exhibits distinct advantage in microporous structure, leading to superior reliability of cell. Based on the understanding of non-woven separator, cell performances of the separator at different charge/discharge conditions are discussed in terms of ion transport of the separator and AC impedance of the cell. Moreover, the problems of nonwoven separator to be solved are clearly stated through the phenomenological analyses. The overall evaluation results indicate that the non-woven PAN separator has many advantages over the PE separator, which, in turn, contribute to superior cell performances. Therefore, the PAN nonwoven membrane can be the most promising candidate for separators of the next generation of lithium-ion battery if the problems to be stated will be solved.