As has been very clear in recent years, the problem of battery short circuiting and overheating cannot be identified at the time the battery was being manufactured . This phenomenon can only occur after a prolonged cycle (use). The market is forcing battery manufacturers to extend battery life, achieve higher energy densities and faster charging times. This will force engineers to design higher density electrodes and use finer, higher porosity separators. The fact is that energy densities are double what they were five years ago using the same materials. The battery separator plays an important role in regulating cell kinetics, enabling ionic flow, preventing electronic contact between the two electrodes and sometimes acting as a safety. device. As the separator is pressed between the two electrodes and filled with electrolyte, it is in contact with all the active components of the cell. By regulating the distribution of electrolytes, it limits the rates of ionic diffusion and recombination and thus has a significant impact on the capacity, power and available energy of cells. Therefore, much work has been done to determine optimal separator characteristics, such as porosity and tortuosity.1-3 Separator degradation has often been observed in certain types of batteries and has been found to be responsible for increased Battery failure or loss of power. [R Kostecki, L Norin, X Song, F McLarnon, Diagnostic Studies of Polyolefin Separators in High Power Li-Ion Cells. Journal of the Electrochemical Society (2004) vol. 151 (4) pp. A522-A526]1Thus, increased energy density (higher pressure on the separator polymer film) and higher power (wide temperature range inside the cell generated by the applied current) and lifetime longer (> 10 years for automobiles. ..... middle of paper ......m environments, expiry point -45). HTI measurements were carried out in a Teflon apparatus with a stainless steel electrode (diameter – 12 mm) placed on the hot plate and connected to the Solartron 1255B (frequency response analyzer) (as above). The temperature range of 50 to 200 °C was monitored at an average rate of 10 °C/min. (the reason why so fast...) The performance of Li-ion cells (assembled with 18650 coated separator and Al pouch cells) such as charge/discharge characteristics and cycle capacity were studied with the Bitrode battery tester.3. Results and discussion The ionic conductivity and MacMullin number data of the uncoated and coated separators are given in Table 2. As for reference, Asahi (PE) and Degussa (PET/ceramic) are also listed. Table 2 Ionic conductivity of separators and MacMullin number (Nm) (electrolyte: 1M LiPF6 in EC:EMC; conductivity - 9.1 mS/cm)