Polymer electrolyte and liquid electrolyte based on sulfolane in full cell LiFePO4│Li4Ti5O12

• Properties of gel electrolyte based on PAN with TMS and modified TiO2-SiO2 is described.
• The highest conductivities were measured for polymer electrolytes with functionalised fillers.
• Electrodes were characterized by EIS, SEM and charging/discharging tests.
• Charge-discharge tests of a LiFePO4|PE3|Li4Ti5O12 and LiFePO4|LE|Li4Ti5O12 cells at different C rates show good capacities.

In the present study, a type of polymer electrolyte (PE) based on a polyacrylonitrile (PAN) polymer network, sulfolane, composite TiO2-SiO2 and vinylene carbonate (VC) as the solid-electrolyte interface (SEI) forming additive were prepared by the casting technique. Liquid electrolyte (LE) was the 1 M LiPF6 in sulfolane (TMS).The produced PE and LE working together with the LiFePO4 (LFP) and Li4Ti5O12 (LTO) was characterized by thermal gravimmetry (TG), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charging/discharging.PE had a high ionic conductivity of 9.8×10−4 S cm−1 at 25 °C (containing sub-microsize TiO2-SiO2 with vinyl groups of the surface—10% by weight). Charging/discharging capacity of the LFP │LE│LTO system was ca. 150 mAh g−1 (VC content 5 wt.%) (C/10 rate). This is much higher in comparison to that characteristic of LFP│PE│LTO cell—charging and discharging capacity stabilizes at a value of ca. 120 mAh g−1.