Synthesis and electrochemical performance of Li3V2(PO4)3/C by organic solvent replacement drying method

A series of Li₃V₂(PO₄)₃/C composite cathodes have been prepared by the organic solvent replacement drying method. Five kinds of organic solvent including ethyl alcohol, butyl alcohol, 2-methoxyethanol, 1,2-propylene glycol, and ethylene glycol were used in the drying process to replace the water respectively. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge tests were employed to analyze the crystal structure, morphology, and electrochemical properties of the as-prepared materials. The results show that the organic solvent has a great influence on the secondary particle size of the as-synthesized materials. Special emphasis is placed on the sample prepared with 1,2-propylene glycol, which has the smallest average particle size and uniform distribution, thus leading to the best high rate performance and long-term cycling stability. The electrode exhibits average specific discharge capacities of 127.6, 128.3, 127.7, 126.7, 125.5, 124.4, 121.9, and 117.0 mAh g^?1 at 0.1, 0.2, 0.5, 1, 3, 5, 10, and 20C, respectively. More encouragingly, this sample delivers an outstanding cycle life with capacity retention of up to 94.68% even after 1000 cycles at 20C. Moreover, EIS results demonstrate that this sample has the minimum resistance and the largest apparent lithium ion diffusion coefficient (1.569 × 10^?7 cm² s^?1) which can facilitate to the Li⁺ diffusion during the charge/discharge process. Our results indicate that this preparation strategy can be facile and versatile for the synthesis of other high-rate and high-capacity intercalation materials.