Preparation and performance of polymer electrolyte based on poly(vinylidene fluoride)/polysulfone blend membrane via thermally induced phase separation process for lithium ion battery

• Polymer electrolyte based on PVDF/PSF blend membrane was prepared via TIPS process.
• Blending PSF promoted the nucleation of PVDF, decreased the size of PVDF spherulite.
• Blending PSF increased the electrochemical stability window of polymer electrolytes.
• Blending PSF markedly enhanced large current charge/discharge performance of cells.

Poly(vinylidene fluoride)/polysulfone (PVDF/PSF) blend microporous matrix of polymer electrolyte for lithium ion battery is prepared via thermally induced phase separation (TIPS) technique. Because of only one parameter, i.e., the PSF/PVDF weight ratio, the membrane microstructure is conveniently controlled. The membrane formation mechanism of PVDF/PSF blend membranes is proposed with the assistance of a binary PSF/PVDF weight ratio-temperature phase diagram. In addition to studying the microstructure and mechanical properties of PVDF/PSF blend membrane, the relationship between properties of membrane, electrochemical performances of corresponding polymer electrolyte and membrane microstructure are also discussed in this paper. It is found that the addition of PSF not only increases ionic conductivity and electrochemical stable window of polymer electrolyte, but also markedly enhances charge–discharge performances of coin cell. The results reveal that PVDF/PSF blend microporous membranes prepared via TIPS technique can be used as polymer matrices of polymer electrolytes for lithium ion batteries.

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