Journal of Membrane Science, Vol.532, 30-37, 2017
Self-supported PVdF/P(VC-VAc) blended polymer electrolytes for LiNi0.5Mn1.5O4/Li batteries
New self-supported poly(vinylidene fluoride)/poly (vinyl chloride-co-vinyl acetate) (PVdF/P(VC-VAc)) blended polymer membranes are prepared via a phase inversion method, and then their electrochemical performances, immersed in the liquid electrolyte as the polymer electrolyte for lithium-ion batteries (LIBs), are evaluated. The Fourier transform infrared spectroscopy analysis, the differential scanning calorimeter test and the X-ray diffraction measurement demonstrate that homogeneous PVdF/P(VC-VAc) polymer composites can form at all blend compositions and the crystallinity degree of the blended polymers decreases as the P(VC-VAc) content increases. Specifically, when the proportion of PVdF/P(VC-VAc) is 70:30 (wt%), membranes with a rich surface and internal porous structure can be acquired. The ionic conductivity of the polymer electrolyte achieves a maximum value of 3.57 mS cm(-1) at room temperature, and favourable electrochemical performances of LIBs can be obtained. LiNi0.5Mn1.5O4/Li cells with the as-prepared polymer electrolyte exhibit a higher initial discharge capacity of 131.0 mAh g(-1) and superior cycle stability with a capacity retention of 96.1% at 0.2 C after 200 cycles compared to cells based on pure PVdF and P(VC-VAc) membranes. This can be attributed to the superior compatibility of the electrolyte with the electrodes. The results also indicate this electrolyte has promising applications in high-voltage LIBs.