Electrochemical performance and stability of a PPy/MMT-PVDF/PMMA composite film at high temperature

A polypyrrole/montmorillonite-polyvinylidenedifluoride/polymethyl methacrylate (PPy/MMT-PVDF/PMMA) composite film was prepared by a solvent casting technique. The surface morphology and cross-sectional structure of the 12 wt.% PPy/MMT-PVDF/PMMA composite film exhibited porosity with high specific surface area and good adsorption capacity. The 12 wt.% PPy/MMT-PVDF/PMMA composite film shows good electrolyte uptake (241%) and electrochemical stability. The ionic conductivity of the 12 wt.% PPy/MMT-PVDF/PMMA composite film with LiPF6 organic electrolyte reaches 2.45 × 10−3 S cm−1 at 20 °C. The Li/LiNi1/3Co1/3Mn1/3O2 cell assembled with the 12 wt.% PPy/MMT-PVDF/PMMA composite film and LiPF6 organic electrolyte exhibits good capacity retention and cycling performance at 1 C and 60 °C. At the same time, the nucleophilic substitution reacts with the PPy/MMT-PVDF/PMMA composite film and HF from hydrolysis by trace moisture of LiPF6 in the electrolyte solution, which can inhibit the disproportionation of Mn3+ in the LiNi1/3Co1/3Mn1/3O2 electrode material and decrease the internal resistance of the cell at high temperature. In conclusion, the PPy/MMT-PVDF/PMMA composite film can be employed in Li-ion batteries.