| 초록 |
Polyimide(PI) composites of separators for lithium-ion batteries (LIBs) was fabricated by electrosprinning with addition of inorganic nanoparticles of SiO2 and Al2O3. The morphology and mechanical properties were investigated by using a field emission scanning electron microscopy (FESEM) and a universal testing machine. Thermal properties were measured by using a thermal gravimetric analyzer (TGA), a hot oven and a differential scanning calorimeter (DSC). The electrochemical performance of PI composites nanofibers as the separator was analyzed by initial charge-discharge capacity, cycle performance and C-rate capabilities test. The results indicated that the PI/SiO2-5% and the PI/Al2O3-5% composite separators exhibited enhanced separator performances such as tensile strength (34.63 and 38.59MPa cm-2) and thermal stability (593.65 and 591.70˚C at 15% loss weight) with high porosity (90.55 and 92.78%) and electrolyte uptake (732.41 and 864.20wt.%). These are compared with physical properties of a commercial separator (SV718), porous polyproplylene in the values of tensile strength of 25.75Mpa cm-2), the thermal stability (381.36˚C at 15% loss weight), the porosity (40.51%) and electrolyte uptake (101.10wt.%). Compared with the SV718 separator, a LiCoO2/Li cell assembled with the PI/SiO2-5% and the PI/Al2O3-5% composite separators demonstrated high initial discharge capacity (168.80 and 170.83mAh g-1) at 0.1C, good stable cycle performance and little capacity lost, which kept above 160.76 and 162.39mAh g-1 at the 50th cycle. |
