Improved electrochemical performance of LiCoPO4 nanoparticles for lithium ion batteries

Single phase LiCoPO4 nanoparticles were synthesized by solid-state reaction. LiCoPO4/Li batteries were fabricated in an argon-filled glove box, and their electrochemical properties were analyzed by cyclic voltammetry (CV) and charge-discharge tests. The structural performance of LiCoPO4 nanoparticles was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD result demonstrated that LiCoPO4 nanoparticles had an orthorhombic olivine-type structure with a space group of Pmnb. The charge-discharge tests indicated that the initial discharge capacity and coulombic efficiency of LiCoPO4/Li batteries were 110 mA h/g and 48% in cut-off voltage range of 3.0-5.3 V, 90 mA h/g and 54% in cut-off voltage range of 3.0-5.1 V, 70 mA h/g and 60% in cut-off voltage range of 3.0-5.0 V, respectively. After 30 cycles, the coulombic efficiency was 78% for 3.0-5.3 V, 88% for 3.0-5.1 V, 91% for 3.0-5.0 V, respectively. These results indicated that the coulombic efficiency of LiCoPO4/Li battery increased upon cycling and upon decreasing in charge upper limit voltage, respectively.