Effect of montmorillonite on the ionic conductivity and electrochemical properties of a composite solid polymer electrolyte based on polyvinylidenedifluoride/polyvinyl alcohol matrix for lithium ion batteries

• Montmorillonite improves the performance solid polymer electrolyte.
• Smaller activation energy is benefit to free lithium ions migration.
• Good performance with low capacity fading on charge–discharge cycling.
• SEI film is formed in the third cycle according to CV curve.
• PVDF/PVA/MMT membrane has good heat stability.

In this study, we prepared a kind of composite solid polymer electrolyte (CSPE) based on montmorillonite (MMT) nano-clay fillers, lithium-bis(trifluoromethanelsulfonyl) (LiTFSI), polyvinylidenedifluoride (PVDF) and polyvinyl alcohol (PVA) copolymer by the casting method. Effect of the montmorillonite on ionic conductivity and electrochemical properties of the polymer electrolyte was demonstrated. The result CSPE obtained a higher ionic conductivity up to 4.31 × 10−4 S cm−1 at room temperature when 4.0 wt% MMT was contained, and the maximum lithium ions transference number of 0.40 was achieved. Electrochemical performance of the polymer solid electrolyte was evaluated in Li/polymer electrolyte/LiFePO4 coin cell. Good performance with low capacity fading on charge–discharge cycling was achieved, indicating the potential application of the as-prepared CSPE in lithium ion batteries.