An In Situ Polymerization Gel Polymer Electrolyte Based on Pentaerythritol Tetracrylate for High-Performance Lithium-Ion Batteries

Problems occur frequently during the application of traditional liquid electrolyte batteries, such as fluid leakage and low energy density. As a product of liquid electrolyte transition to solid electrolyte, gel polymer electrolyte has its own advantages for achieving high conductivity and good thermal stability. In this study, pentaerythritol tetracrylate (PETEA) was used as the precursor to prepare polymer-based materials with the assistance of azobis(isobutyronitrile) (AIBN) as the initiator. Because fluorine is beneficial to improving the migration efficiency of Li⁺ and the electrochemical performance of the gel polymer electrolyte, dodecafluoroheptyl methacrylate (DFHMA) is introduced to the PETEA-based gel polymer electrolyte (GPE) system. The DFHMA-introduced GPE shows better electrochemical performance, battery cycle performance, conductivity, and lithium-ion migration number compared with the pristine PETEA-based GPE. In particular, the DFHMA-introduced GPE exhibits the best performance because the molar ratio of PETEA to DFHMA is 5:1. Herein, the electrochemical window is 4.6 V, the ionic conductivity reaches 1.207 mS cm^-1, and the number of lithium-ion migrations reaches the value of 0.663. Because the electric current density is 2 C, the specific capacity of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523)/GPE/Li reaches 143.1 mAh g^-1 after 100 cycles.