Improved electrochemical performance of 5 V LiCoPO4 cathode materials via yttrium doping

• We successfully synthesized Y-doped LiCoPO4 via a citric acid-based sol–gel route.
• Y-doping can optimize the morphology and crystal microstructure of LiCoPO4.
• Y-doped LiCoPO4 presents a higher discharge capacity and better cyclic stability.

Pure and Y-doped LiCoPO4 samples are prepared by a citric acid-based sol–gel route followed by heat treatment. X-ray diffraction, scanning electron microscopy and charge–discharge tests show that a small amount of Y3 + doping can significantly improve the capacity delivery and cycling properties of LiCoPO4 without affecting its structural properties. Y-doped LiCoPO4 (x = 0.01) cathode material presents a high discharge capacity of 154.3 mAh g− 1 (0.1 C) at room temperature. Cyclic voltammetric and electrochemical impedance spectra tests disclose that the Li-ion diffusion, the reversibility of lithium extraction/insertion, electrical conductivity and electrochemical reaction are significantly improved in Y-doped LiCoPO4.