Synthesis and low temperature electrochemical properties of CeO2 and C co-modified Li3V2(PO4)(3) cathode materials for lithium-ion batteries

摘要

Li3V2(PO4)(3)/C was prepared as a pristine material by an improved sol-gel method. Then different amounts of CeO2 were employed to modify Li3V2(PO4)(3)/C cathode materials via a suspension mixing method assisted by polyvinyl alcohol. The 2 wt% CeO2 modified sample (Ce-2) exhibits the best initial charge-discharge performance at -20 degrees C with a specific capacity of 70.4 mAh g(-1) and 103.3 mAh g(-1) at 1 C in the potential range of 3.0-43 V and 3.0-4.8 V, respectively. The Ce-2 electrode still delivers a stable cycling performance with 95.6 % and 92.7 % capacity retention after 50 cycles even at 5 C and at 0 degrees C in the potential range of 3.0-4.3 V and 3.0-4.8 V, respectively. The electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements indicate that the resistance and polarization of Ce-2 at low temperatures are lower than those of any other samples. In addition, the Ce-2 delivers the highest Li-ion diffusion coefficient derived from PSCA measurement, which further verifies that the electrochemical kinetics of Ce-2 is much more active than that of the pristine sample. The excellent low-temperature performances obtained in this work suggest that CeO2-modified Li3V2(PO4)(3)/C material is a promising cathode candidate for battery applications at low temperature conditions. (C) 2015 Elsevier Ltd. All rights reserved.