An In Situ Polymerization\nGel Polymer Electrolyte\nBased on Pentaerythritol Tetracrylate for High-Performance Lithium-Ion\nBatteries

Problems occur frequently during the application of traditional\nliquid electrolyte batteries, such as fluid leakage and low energy\ndensity. As a product of liquid electrolyte transition to solid electrolyte,\ngel polymer electrolyte has its own advantages for achieving high\nconductivity and good thermal stability. In this study, pentaerythritol\ntetracrylate (PETEA) was used as the precursor to prepare polymer-based\nmaterials with the assistance of azobis(isobutyronitrile) (AIBN) as\nthe initiator. Because fluorine is beneficial to improving the migration\nefficiency of Li<sup>+</sup> and the electrochemical performance of\nthe gel polymer electrolyte, dodecafluoroheptyl methacrylate (DFHMA)\nis introduced to the PETEA-based gel polymer electrolyte (GPE) system.\nThe DFHMA-introduced GPE shows better electrochemical performance,\nbattery cycle performance, conductivity, and lithium-ion migration\nnumber compared with the pristine PETEA-based GPE. In particular,\nthe DFHMA-introduced GPE exhibits the best performance because the\nmolar ratio of PETEA to DFHMA is 5:1. Herein, the electrochemical\nwindow is 4.6 V, the ionic conductivity reaches 1.207 mS cm<sup>–1</sup>, and the number of lithium-ion migrations reaches the value of 0.663.\nBecause the electric current density is 2 C, the specific capacity\nof LiNi<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>O<sub>2</sub> (NCM523)/GPE/Li reaches 143.1 mAh g<sup>–1</sup> after 100\ncycles.