Influence of the Preparation Process on the Electrochemical Properties of xLiFePO₄·yLi₃V₂(PO4)₃/C Nano-Sized Composite Cathode Materials

Abstract:

In this paper, a series of xLiFePO₄·yLi₃V₂(PO₄)₃/C (x/y = 1:0, 7:1, 5:1, 3:1, 1:1, 1:3 and 0:1, ratio in mol) nano-sized composite cathode materials were successfully prepared via the solid reaction method. Influence of x/y ratio, calcination temperatures and the content of citric acid on the composition, microstructure and electrochemical properties of the materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical measurements, et al. results showed that the xLFP·yLVP/C (x and y ≠ 0) composites were composed of olivine LiFePO₄ and monoclinic Li₃V₂(PO₄)₃, both of which featured slight structural distortions as the formation of V-doped LFP/C and Fe-doped LVP/C, respectively; With the increase of calcination temperatures, the crystallinity and particles size of the 7LFP·LVP/C composites increased, when calcined at 700°C, the initial charge/discharge specific capacity of the composites reached a maximum value of 145.6 mAh/g, and the voltage drop values between charge/discharge platform possessed the minimum value(0.04 V), suggesting the minimum polarization of the composites in charge/discharge process. Content of citric acid did not affect the compositions of the composites, with the increase of the molar ratio of citric acid to V³⁺, the discharge specific capacities of 7LFP·LVP/C increased first and then decreased, when it equaled to 1.0:1.0, the discharge specific capacity of the relative composites was 119.18 mAh/g, with a capacity retention rate of 93.9 % after 50 cycles, owning the excellent electrochemical stability.

• Periodical: Key Engineering Materials (Volume 680)
• Pages: 238-243
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.680.238
• Online since: February 2016
• Authors: Bing Yan, Peng Zhao Gao*, Dong Yun Li, Guang Lei Tian
• Keywords: Electrochemical Properties, Microstructure, Preparation Process, xLiFePO₄·yLi₃V₂(PO4)₃/C

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