The nanofiber gel electrolytes with ultra-high ionic conductivity regulated by different acid radical ions for lithium batteries

A nanofiber gel electrolytes with excellent physical properties, electrochemical properties, and cycle life based on poly(vinylidene fluoride)-hexafluoropropylene copolymer modified by magnesium–aluminum bilayered nanosheets (MgAl-LDs) intercalated with different acidic roots ions is prepared by electrostatic spinning. The electrolytes exhibit the best elongation at break of 166 % and tensile strength of 6.59 MPa, and the electrochemical windows are all higher than 5 V. Meanwhile, the ionic conductivity number of nano-GPE intercalated with CO32–, ClO4−, and NO3– reach 5.55*10−3 S/cm, 5.04*10−3 S/cm, and 6.93*10−3 S/cm, respectively. The Li//Li symmetric battery can be stably cycled for more than 1000 h at 1 mA/cm2 with an overpotential of less than 50 mV. The LiFePO4// Li batteries assembled with nano-GPE modified by MgAl-LDs (s = NO3–) show better 0.1-2C multiplicity performance than CO32– and ClO4−, accompanied by an optimal discharge capacity of up to 155 mAhg−1 at 0.1C as well as a high reversible capacity of 135 mAhg−1 and a capacity retention rate of 90 % after 100 cycles at 0.5C. In addition, the results of polarization, X-ray photoelectron spectroscopy (XPS), Computed Tomography (CT), and scanning electron microscope (SEM) tests show that a stable SEI film is formed between nano-GPE and Li anode.