Research On The Separatrs Of Lithuim-ion Battery And Sodium-ion Battery

New energy storage systems including lithium-ion battery(LIB) and sodium-ionbattery(SIB), compared with other lead-acid cell and nickel-cadmium cell, lithium-ionbattery and sodium-ion battery have the advantage of high specific capacity, longcycle life and environmental friendly, so the lithium-ion battery is widely used on cellphones, camera, computer and other electronic equipment. With the demand ofsustainability development, also solving the problem of the shortage of lithium,researchers pay much attention on sodium-the same main group element of lithium.The sodium resource is much more abundant than lithium on earth. But manyresearches cared about the cathode and anion electrode materials of LIB and SIB,ignored the battery electrolyte. The ordinary liquid electrolyte system consists ofinorganic s traditional liquid electrolyte. alt, electrolyte solvent and separators.Thisresearch focus on the separators used in LIB and SIB. For the LIB, we coated theelectrospun PVDF nanofibers with polydopamine, increasing the hydrophilic abilityof the LIB separators; For the SIB battery, we invented the sodium ion exchangedPFSA membrane instead of theFirstly, for the LIB separators, we coated the electrospun PVDF nanofibers withpolydopamine, which will increase the separators electrolyte uptake ability. We testthe FTIR, XPS, Contact angle, SEM and DSC properties of the PVDF andPDA-PVDF membrane to compare the difference before and after coating, also weassembled the LiMnO4/Li batteries with different separators to test the cycle stabilityand ratio properties. From the test result we got the information that after the coatingprocess, the hydrophilic ability improved, the electrolyte uptake improved, also theion conductivities improved. The cycle capacity fading after200cycles forPDA-PVDF separators battery was4.3%, less than the PVDF membrane13.4%, alsowe tested the different ration ability. From the result we found that the PDA-PVDFperformed well than the PVDF membrane. Secondly, we invented the sodium ion exchanged PFSA-Na membrane soaked inorganic solvent as the SIB separators instead of the liquid NaClO4electrolyte. Alsowe compared our PFSA-Na membrane with the Dupont’s Nafion115membrane.Through the test and result, at the cycle ratio0.1C, our PFSA-Na membrane specificcapacity was90mAh/g, close to the liquid NaClO4electrolyte, but after50cycles, theliquid NaClO4electrolyte capacity fading was nearly50%, higher than our PFSA-Namembrane system2.4%. This can be explained that the PFSA-Na membrane workedas both separators and sodium salt, avoiding the decomposition of the inorganic salt.Also as our PFSA-Na membrane ion exchanged ration was1.18higher than theNafion-Na membrane0.9, the specific capacity90mAh/g was higher than that of theNafion-Na membrane battery system, which was67.6mAh/g.