Control the explosive polymerization of 1,3-dioxolane in LiPF6 electrolyte by Lewis acid-base interactions

1,3-dioxolane (DOL) shows low interfacial impedance and high Coulombic efficiency, thus its polymer electrolytes have attracted extensive attention. In order to initiate DOL polymerization, catalyst amount of LiPF6 is usually used rather than as the main lithium salt. Totally replacement of LiTFSI with low cost of LiPF6 could bring the heat explosion and high viscosity when mixing DOL with 0.9 M LiPF6 electrolyte (carbonate ester solvent). Here, based on the Lewis acid-base interaction, a new type of Lewis base, pyridine, is added to control the explosive polymerization of 1,3-dioxolane in LiPF6 electrolyte. Through tuning the pyridine content, the gelling process and electrochemical properties could be controlled. It is demonstrated that the optimized monomer conversion and electrochemical window are up to 85.2 % and 4.6 V; meanwhile, the optimized conductivity and transfer number are 0.99 x 10(-3) S/cm (25 degrees C) and 0.68, respectively. The stable interface between PDOL and lithium metal anode could be proved by the stable over-potential (50mv, 700 h) at current density of 0.5 mA cm(-2). After 500 cycles at 2C, the assembled Li/PDOL@py(0.125)/LiFePO4 battery delivers 115 mAh/g and 90 % capacity retention, with high average Coulombic efficiency of 99.83 %. The present results demonstrate the heat suppression role of pyridine toward mixing DOL with 0.9 M LiPF6 electrolyte, which solves the heat and viscosity problems for PDOL based gelling polymer electrolytes.