FePO4-coated Li5Cr7Ti6O25 nanocomposites as anode materials for high-performance lithium-ion batteries

Abstract FePO4 coated Li5Cr7Ti6O25 nanocomposites are synthesized according to a simple sol–gel method following by a calcination procedure. XRD and Rietveld refinement result indicate that FePO4 decorating does not change the crystal structure and lattice parameters of Li5Cr7Ti6O25. SEM and TEM prove that the particle size of all sample are evenly distributed in the 50–100 nm range. Both energy dispersion spectroscopy mapping and HRTEM indicate the existence of FePO4 on the surface of Li5Cr7Ti6O25, which provides a good conductive contact. CV and EIS exhibit that FePO4 (3 wt%) coated Li5Cr7Ti6O25 material has lower polarization, larger Li+ diffusion coefficient and higher conductivity than other pure Li5Cr7Ti6O25 and other FePO4 coated Li5Cr7Ti6O25 composites. Therefore, FePO4 (3 wt%) coated Li5Cr7Ti6O25 anode material displays the highest charge and discharge capacity at each rate. The enhanced electrochemical performance of FePO4-coated Li5Cr7Ti6O25 result from the enhanced lithium ion and electron transfer kinetics. The pristine Li5Cr7Ti6O25 only shows a specific capacity of ∼197 mAh g−1 at 500 mA g−1 after 100 cycles, but FePO4 (3 wt%)-coated Li5Cr7Ti6O25 achieves a high capacity of ∼237.9 mAh g−1. Therefore, the FePO4 coating can be regarded as a promising strategy to improve the electrochemical properties of Li5Cr7Ti6O25.