Facile fabrication of polyacrylonitrile/alumina composite membranes based on triethylene glycol diacetate-2-propenoic acid butyl ester gel polymer electrolytes for high-voltage lithium-ion batteries

Mechanically robust polyacrylonitrile/alumina (PAN/Al₂O₃) composite membranes were fabricated by electrospinning mixed solution of PAN and Al₂O₃ nanoparticles. The as-prepared composite membranes of a three-dimensional network based on uniform polymeric interconnected structures exhibit excellent mechanical properties along with high porosity (~64%), high electrolyte uptake (~470%) and good relative absorption ratio (~62% of the initial absorption). The introduced Al₂O₃ nanoparticles significantly improved the electrolyte compatibility, thermal properties and wettability of membranes. The fabricated PAN/Al₂O₃-triethylene glycol diacetate-2-propenoic acid butyl ester (PAN/Al₂O₃-TEGDA-BA) gel electrolytes via immersing membranes in TEGDA-BA show high ionic conductivity up to 2.35×10^-3Scm^-1 at 25°C, coupled with high electrochemical stability (>4.5V vs. Li/Li⁺). The half-cells based on Li[Li_1/6Ni_1/4Mn_7/12]O_7/4F_1/4 electrodes demonstrate remarkably stable charge/discharge performance and excellent capacity retention of ~240.4mAhg^-1 (0.1C) after 50 cycles with a cut-off voltage of 4.8V. The results suggest a facile strategy for scalable fabrication of high-performance polymer electrolyte membranes in high-voltage lithium ion batteries.