Effects of nickel-doping on the microstructure and electrochemical performances of electrospun Li3V2(PO4)3/C fiber membrane cathode

Abstract

Metal ion-doping and fibrosis treatment are important ways to improve the conductivity of lithium vanadium phosphate (Li3V2(PO4)3) electrode materials. However, the traditional casting preparation method could reduce the electronic and ionic conductivities of Li3V2(PO4)3 electrodes. In this work, the nickel (Ni)-doped Li3V2(PO4)3/C nanofiber membrane with a three-dimensional network structure was prepared by an electrospinning technique, which was directly used for self-standing cathodes in lithium-ion batteries. The effects of Ni-doping on the morphology, structure, and electrochemical properties of Li3V2(PO4)3/C nanofiber membrane were studied. The results show that the Ni-doping not only changes the crystal structure and morphology of Li3V2(PO4)3/C fibers, but also affects the electrochemical performances of the Li3V2(PO4)3/C electrodes. 1‰ Ni-doping has slightest effect on the crystal structure compared with other ratios, and the catalytic effect of Ni nanoparticles makes Li3V2(PO4)3/C grow directionally to form a hybrid membrane containing Li3V2(PO4)3/C nanofibers and Li3V2(PO4)3/C nanowires. The hybrid membrane electrode possesses good electrochemical performances at the current densities of 1C and 5C owing to the long-range continuous electron conductive networks, high porosity to favor the electrolyte permeation and Li-ion transport, and stable integrated-electrode structure to enhance the redox reaction. This self-standing Li3V2(PO4)3/C nanofiber membrane cathode is expected to be used in high-energy lithium-ion batteries.