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A novel 2Li 3 V 2 (PO 4 ) 3 ·LiV 3 O 8 composite with short rod and thin plate shapes is synthesized through sol–gel method followed by hydrothermal and solid–state reaction. LiV 3 O 8 is used as an additive to improve the capacity of Li 3 V 2 (PO 4 ) 3 . In the composite cathode, active impurity phase Li 0.3 V 2 O 5 is also present, which has little impact on the whole electrochemical properties. The 2Li 3 V 2 (PO 4 ) 3 ·LiV 3 O 8 composite delivers a high initial capacity of 162.8 mAh g −1 at a current density of 100 mA g −1 in the voltage range of 2.0–4.3 V. Furthermore, the composite with high crystallinity also shows high electrochemical reversibility and good rate capability. The diffusion coefficient of Li ions in the composite is in the range of 10 −11 –10 −9 cm 2 s −1 obtained from galvanostatic intermittent titration technique. [ABSTRACT FROM AUTHOR]

Abstract: Li3V2(PO4)3/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700°C. The Li3V2(PO4)3/C electrode presents a high initial discharge capacity of 84.3, 111.1, 128.7, 129.2 and 132.1mAhg−1 at −20, 0, 25, 40 and 65°C between 3.0 and 4.3V, and 118.9, 132.1, 187.6, 180.3 and 172.2mAhg−1 between 3.0 and 4.8V at 0.1C, respectively. However, the electrode only delivers small discharge capacities at −20°C at 10C rate. The capacity fade at low temperatures is mainly attributed to the reduced ionic and electronic conductivity of the electrolyte, the increased impendence of solid electrolyte interface (SEI) and charge-transfer resistance on the electrolyte–electrode interfaces. At higher temperatures, the capacity increases with increasing temperature between 3.0 and 4.3V, but decreases between 3.0 and 4.8V. In the potential range of 3.0–4.8V, the larger crystal structural distortion and non-uniformity of SEI layer at high temperatures may be the main reasons for the capacity loss. [Copyright &y& Elsevier]

Abstract: Plate-like Li3V2(PO4)3/C composite is synthesized via a solution route followed by solid-state reaction. The Li3V2(PO4)3/C plates are 40–100nm in thicknesses and 2–10μm in lengths. TEM images show that a uniform carbon layer with a thickness of 5.3nm presents on the surfaces of Li3V2(PO4)3 plates. The apparent Li-ion diffusion coefficient of the plate-like Li3V2(PO4)3/C is calculated to be 2.7×10−8 cm2 s−1. At a charge–discharge rate of 3C, the plate-like Li3V2(PO4)3/C exhibits an initial discharge capacity of 125.2 and 133.1mAhg−1 in the voltage ranges of 3.0–4.3 and 3.0–4.8V, respectively. After 500 cycles, the electrodes still can deliver a discharge capacity of 111.8 and 97.8mAhg−1 correspondingly, showing a good cycling stability. [Copyright &y& Elsevier]

Abstract: Spherical Li3V2(PO4)3/C composites are synthesized by a soft chemistry route using hydrazine hydrate as the spheroidizing medium. The electrochemical properties of the materials are investigated by galvanostatic charge–discharge tests, cyclic voltammograms and electrochemical impedance spectrum. The porous Li3V2(PO4)3/C spheres exhibit better electrochemical performances than the solid ones. The spherical porous Li3V2(PO4)3/C electrode shows a high discharge capacity of 129.1 and 125.6mAhg−1 between 3.0 and 4.3V, and 183.8 and 160.9mAhg−1 between 3.0 and 4.8V at 0.2 and 1C, respectively. Even at a charge–discharge rate of 15C, this material can still deliver a discharge capacity of 100.5 and 121.5mAhg−1 in the potential regions of 3.0–4.3V and 3.0–4.8V, respectively. The excellent electrochemical performance can be attributed to the porous structure, which can make the lithium ion diffusion and electron transfer more easily across the Li3V2(PO4)3/electrolyte interfaces, thus resulting in enhanced electrode reaction kinetics and improved electrochemical performance. [Copyright &y& Elsevier]