Ionic liquid modified carbon nanotubes doped gel polymer electrolyte for fast charging lithium metal batteries

Fast charging enables batteries to rejuvenate in a fraction of time, which is critical for the next-generation energy storage devices. However, the increased security risks and capacity attenuation brought by fast charging seriously hinder the practical application of this technology. To address these issues, a novel gel polymer electrolyte (GPE) based on polyvinylene carbonate, poly (ethylene oxide), poly (vinylidene fluoride-co-hexafluoropropylene), and ionic liquid modified carbon nanotubes (IL-CNTs) has been successfully prepared by solution casting method. The complementary interactions between polycarbonate, polyether and IL-CNTs can effectively improve the transportation of lithium ion, thereby the ionic conductivity and lithium-ion transference number ameliorate to 0.71 mS cm−1 and 0.51, respectively at 30°C. On account of the mechanical strength enhancement function of IL-CNTs, the GPE exhibits an electrochemical window of 4.74 V, which adequately satisfies the match of GPE to various high-voltage cathodes. The LiFePO4 cell possesses a high retention ability of 85.6% after 1000 cycles at 4C and the initial discharge capacity reaches 111 mAh g−1. This work provides a valuable guideline for designing GPEs accommodating fast charging with long cycle life.