A high-stable polyacrylonitrile/ceramic composite membranes for high-voltage lithium-ion batteries

Polymer/ceramic composite gel electrolytes are considered promising alternatives to conventional liquid electrolytes for developing high-energy and safer lithium-ion batteries (LIBs). In this study, we prepare three polyacrylonitrile (PAN)/ceramic composite membranes with 40 wt% Al₂O₃, BaTiO₃, and TiO₂ ceramic nanoparticles and compared their properties with those of pristine PAN. Structural and morphological investigations confirm the formation of the polymer/ceramic composites. The interconnected microporous structure PAN/ceramic composites efficiently entrapped a large amount of liquid electrolyte and exhibit improved ionic conductivity compared to that of the pristine PAN electrolyte. The PAN/Al₂O₃ composite electrolyte displays the highest ionic conductivity of 5.2 × 10⁻³ S cm⁻¹ under ambient conditions with low Li⁺-coordinated EC and high free PF₆⁻ concentration. Thermal shrinkage tests indicate that the addition of ceramic particles enhance the thermal stability of the PAN/ceramic membranes, as compared to that of commercial polyethylene separators. The PAN/ceramic composite electrolytes are tested as separator-cum-electrolytes in lithium-ion batteries using a LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) high-voltage cathode, and a lithium metal anode. The LIB with the PAN/Al₂O₃ composite electrolyte delivers a high capacity of 184 mAh g⁻¹ at 0.5 C, which is retained at 85% after 100 cycles, demonstrating the best rate performance among all tested composite electrolytes.