Nb5+ doped Li1.20Mn0.54Ni0.13Co0.13O2 with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) surface modification as advanced cathode material for Li-ion batteries

The conductive polymers PEDOT:PSS coated Li1.20[Mn0.53Ni0.13Co0.13Nb0.01]O2 cathode materials were synthesized via using the sol-gel method, followed by the wet solution process. And the X-ray diffraction (XRD), Rietveld refinement, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) were adopted to investigate the morphology and constituents of as-prepared cathode materials. The results demonstrated that a PEDOT:PSS layer was uniformly distributed on the surface of bulk Li1.20Mn0.54Ni0.13Co0.13O2 with Nb5+ doping successfully. And the PEDOT:PSS surface coating and Nb5+ doping modifications showed a significant improvement on the electrochemical properties of cathode. In particular, the 2 wt% PEDOT:PSS coated Li1.20[Mn0.53Ni0.13Co0.13Nb0.01]O2 delivered a supernal discharge capacity of 145.6 mAhg−1 at 5C high rate and retained a high capacity retention of 90.8% after 200 cycles at 45 °C, which were more superior than those of the pristine cathode (90.2 mAhg−1 and 80.7%). The enhanced electrochemical properties could be attributed to the facilitation of Lithium ions diffusion, the lower cation mixing and restriction of the side reactions between cathode surfaces with electrolyte by the Nb5+ doping and PEDOT:PSS coating.