Enhance electrochemical performance of LiFePO4 cathode material by Al-doped Li7La3Zr2O12 and carbon co-coating surface modification

Abstract A composite solid electrolyte based on Al-doped Li7-3xAlxLa3Zr2O12 (LALZO) was synthesized by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were used to characterize Li7La3Zr2O12 (LLZO) precursors with different Al doping concentrations. The results show that LLZO precursor doped with 0.4 mol% Al (LALZO-4) has high stability and good crystallinity. Further, this composite solid electrolyte was co-coated with carbon to optimize the LiFePO4 battery. Electrochemical performance tests show that the LiFePO4/C battery with 5% LALZO-4 precursor (LFP-5) exists in the form of uniformly dispersed spherical particles, and exhibits excellent cycling stability and high rate performance. In addition, the LALZO-4 coating layer can increase the diffusion rate by reducing the charge transfer resistance.