## 3 Results and Discussion
### Cell Performance of the Fabricated PVDF-HFP Multilayered Porous Film  
Figure 5a presents the comparable charge-discharge performance outcomes of the battery cells in the second cycle which was cycled in the cutoff voltage range of 3.5-4.9 V at a current density of 0.1 C. The discharge capacities of the battery cells assembled with the two-, three-, and four-layer membranes were 95.8, 101.5, and 89 mAh g\({}^{-1}\), respectively, all of which were higher than discharge capacity of the commercial Celgard separator (87.1 mAh g\({}^{-1}\)). For a long-term stability test, cells composed of layered membranes and a commercial separator were tested with a C-rate of 1.0 C for 50 cycles, as shown in Figure 5b. As can be seen in Figure 5b, the initial discharge capacities of the cells assembled with the layered membranes were higher than that of the commercial Celgard separator. The capability retentions of the cells with the two-, three-, and four-layer membranes and the commercial Celgard separator were found to be 90, 95, 97, and 97%, respectively. Although cell with two-layer membrane demonstrated lower cycling stability, however, cells with the three-layer and four-layer membranes showed cycling stability comparable to a cell with a commercial separator. Figure 5c presents the discharge capability of cells assembled with the layered membranes and the commercial Celgard separator under various discharge conditions (0.1 C, 0.2 C, 0.5 C, 1 C, 2 C). As can be seen, all of the cells assembled with the layered membranes demonstrated higher discharge capacities than the capacity determined for Celgard separator at C-rates ranging from 0.1 to 2 C. The discharge capacity regularly dropped with an elevated discharge current density. However, the difference in the discharge capability between the layered membranes and the Celgard separator became more significant at higher discharge current densities. Among those samples, the cell with the three-layer membrane exhibited the best rate performance, corresponding to 89% of the capacity at the 0.1 C rate. The obtained results suggest that the three-layer membrane is a promising separator for high-power and rapidly charging LIBs with outstanding cycle lifetimes. The high capacities, as well as the excellent rate behaviors of the cells assembled with the layered PVDF-HFP membranes, are mainly due to the good interfacial compatibility with the electrodes, the highly microporous network, and the thinness of the cell. Such favorable parameters of developed membranes facilitate rapid transport of the ionic charge carriers for electrochemical reactions and provide the low internal resistance values at high current density levels.  
Figure 4: Stress-strain curves of the layered membranes and the commercial Celgard separator (transversal direction) as a reference. The inset demonstrating the dimensional shrinkage of the four-layer membrane and the commercial Celgard separator before and after thermal treatment at 150 \({}^{\circ}\)C for 30 min.  
Figure 5: Electrochemical characterizations of coin-type half cells with the two-, three-, and four-layer membranes and the Celgard separator: (**a**) Charge and discharge curves of coin cells during the second cycle. All cells were cycled at a rate of 0.1 C between 3.5 and 4.9 V. (**b**) Cycle performances of coin cells with a C-rate of 1.0 C. (**c**) Rate capabilities of the coin cells. The voltage range for these measurements was between 3.5 and 4.9 V.