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 LiPF 6 is usually used rather than as the main lithium salt . Totally replacement of LiTFSI with low cost of LiPF 6 could bring the heat explosion and high viscosity when mixing DOL with 0.9 M LiPF 6 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 LiPF 6 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 × 10 −3 S/cm (25 °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 /LiFePO 4 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 LiPF 6 electrolyte, which solves the heat and viscosity problems for PDOL based gelling polymer electrolytes .
危险品化学品经营许可证（带存储）