The Enhanced Performance Of Polyethylene Composite Separators By The Modification Of Lithium Salt@Sio2 Nanoparticles

Improving the dimensional thermal stability and electrochemical performance of polyethylene (PE) membrane is critical to enhance the safety performance of lithium-ion battery. In this paper, PE membranes are modified by lithium bis(trifuoromethanesulfonyl)imide (LiTFSI) solution and then coated with nano-SiO2/polyvinyl alcohol solution to obtain composite membranes (PE@LnSiO(2), where n represents the concentration of LiTFSI solution). The obtained PE@L4SiO(2) (LiTFSI solution concentration is 4%) composite membrane possesses a thermal shrinkage rate of only 17% at 150 degrees C, which is far superior to that of the PE separator. The ionic conductivity of the composite membrane is 16.9 x 10(-4) S cm(-1) at room temperature (RT), and the battery impedance decreases to 154 omega, which is remarkably better than that of the PE membrane (188 omega). The battery delivers a reversible discharge capacity of 164 mAh g(-1) at 0.2 C under RT after 250 cycles, and the coulomb efficiency remains above 99%. The battery also has a high discharge capacity of 132 mAh g(-1) at 2 C, which indicates that it has excellent rate performance. Therefore, this research successfully explores a simple method to effectively improve the dimensional thermal stability of PE separator, as well as the electrochemical and safety performance of lithium battery.