Polyethylene glycol-induced growth of LiFePO4 platelets with preferentially exposed (010) plane as a cathode material for lithium ion battery

Abstract

Rhombohedron-like LiFePO4 platelets with preferentially exposed (010) plane are synthesized via solvothermal reaction using 30vol.% Polyethylene glycol (PEG) solution as solvent. The mechanism of the PEG-induced crystal growth of the LiFePO4 platelets under solvothermal circumstance is revealed. The crystal structure, micro morphology and electrochemical performance of the prepared LiFePO4 platelets are studied by means of X-Ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge test. Due to the preferential growth of (010) lattice plane facilitating diffusion of Li-ions, the LiFePO4 material shows excellent electrochemical performance. The as-obtained products deliver initial discharge capacities of 166.8mAhg−1 with an initial Coulombic efficiency of 99.4% at 0.1C, discharge capacities of 144.7mAhg−1 at 1C and discharge capacities of 116.5mAhg−1 at 5C. Moreover, the discharge capacities after 262cycles at 1C are 142.4mAhg−1 (capacity retention is 98.4%). This solvothermal reaction approach is a promising strategy for the commercialization of LiFePO4 cathode in lithium ion batteries.