Design and analysis of an optimal cathode for Li-LiV3O8 secondary cells

Abstract

Lithium trivanadate (LiV3O8) and lithium vanadate (LixV2O5 ) composites were synthesized by a solid-state method in order to obtain higher capacity and electrical conductivity. Two types of LixV2O5 combined with LiV3O8 were obtained depending on the heating temperature. To determine the optimal ratio of the two materials, the cells assembled with these composites were cycled at a rate of 0.2C, and each component was analyzed by the Rietveld refinement. The LiV3O8/LixV2O5 composites synthesized at 600 degrees C showed a higher discharge capacity and better capacity retention (259 mA h g(-1) and 85%, respectively, after the 50th cycle) compared to those synthesized at other temperatures. The composites were characterized by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and particle size analysis. The electrochemical performance was analyzed using a battery testing system and impedance spectroscopy. The composites have increased intrinsic electrical conductivity with high lithium-ion coefficients, reduced electrochemical reaction resistance, and homogeneous particle size distributions with large surface areas. Therefore, the optimally synthesized composites are promising cathode materials for direct application in new battery systems using lithium. (C) 2019 Elsevier B.V. All rights reserved.