Highly conductive polymer electrolytes based on PAN-PEI nanofiber membranes with in situ gelated liquid electrolytes for lithium-ion batteries

Abstract

The development of solid state electrolytes is considered as an effective approach to build safer lithium-ion batteries by replacing the conventional liquid electrolytes. However, the solid state electrolytes face continuous challenges to improve their ionic conductivities and mechanical properties. Herein, we report the synthesis of novel polymer electrolytes based on cross-linked polyacrylonitrile-polyethylenimine (PAN-PEI) nanofiber membranes infiltrated with in-situ gelated electrolytes using tripropylene glycol diacrylate as crosslinking agent in the organic carbonate-based liquid electrolytes. The PAN-PEI nanofiber membranes with different mass ratios of PAN/PEI prepared by electrospinning method are constructed with entangled nanofibers of an average diameter of ~600 nm. The optimized PAN-PEI based electrolyte has a high ionic conductivity up to 3.39 mS cm−1 at room-temperature and decent tensile strength of 9.36 MPa. Linear sweep voltammetry shows that the polymer electrolyte also has a wide electrochemical window of 5.4 V (vs. Li/Li+). This polymer electrolyte exhibits excellent cycling stability even in the high energy density of LiNi0.8Co0.1Mn0.1O2/Graphite, delivering an initial discharge capacity of 175 mAh g−1 at 0.5 C with a capacity retention of 91.4% after 200 cycles.