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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: Novel Li1.2Mn0.5Co0.25Ni0.05O2 microcube is prepared through a simple binary template method. After calcined at 800 °C, lithium and nickel are permeated into the cathode material and a well-crystallized Li-rich layered oxide is obtained. Furthermore, hollow circle cube architecture is formed due to the decomposing of the carbonate. As a cathode material for lithium ion batteries (LIBs), the oxide with such architecture can deliver high initial discharge capacity of 272.9 mAh g−1 at a current density of 20 mA g−1. High reversible discharge capacities of 208 mAh g−1 and 110 mAh g−1 are obtained at a current density of 200 mA g−1 and 2000 mA g−1, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are performed to further study the hollow Li1.2Mn0.5Co0.25Ni0.05O2 microcube. It is remarkable that such architecture makes the Li-rich layered oxide Li1.2Mn0.5Co0.25Ni0.05O2 a promising cathode material for LIBs. [Copyright &y& Elsevier]

Abstract: LiVO3 materials are synthesized by combustion method with oxalic acid as fuel. Owing to its relatively low crystallization and small particle size, the LiVO3 calcined at 450 °C for 2 h displays optimal electrochemical performances, delivering a high discharge capacity of 298.4 mAh g−1 and 262.5 mAh g−1 between 1.0 and 3.5 V at a current density of 50 mA g−1 and 500 mA g−1 respectively, and exhibiting good cyclic stability. In this work, the chemical diffusion coefficient of Li+ (D Li+) in the LiVO3 electrode is determined by electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The value calculated by EIS is in the range of 10−9–10−8 cm2 s−1, while it calculated by GITT is 10−9.5–10−8 cm2 s−1. [Copyright &y& Elsevier]

Abstract: LiF is successful used to modify the surface of layered LiNi1/3Co1/3Mn1/3O2 via a wet chemical method followed by an annealing process. The lattice structure of LiNi1/3Co1/3Mn1/3O2 is not changed distinctly after modification and part of F− dopes into the surface lattice of the oxide. The LiF-modified oxide exhibits capacity retentions of 97.5% at 0.1 C at room temperature and 93.5% at 1 C at 60 °C after 50 cycles, and delivers a high discharge capacity of 137 mAh g−1 at 10 C at room temperature. Furthermore, it has reversible capacities of 124.4 mAh g−1 at 1 C at 0 °C and 85.6 mAh g−1 at 0.1 C at −20 °C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests show that the LiF-modified layer can reduce the dissolution of metal ions in the electrode and enhance the conductivity of the oxide surface through partly F-substitution. LiF modification will be promising for the application of layered oxide for lithium ion batteries. [Copyright &y& Elsevier]

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: Rod-like LiV3O8 composites have been fabricated by using a carbamide-assisted rheological phase reaction method. The electrochemical performances of the LiV3O8 materials prepared under different conditions are investigated by cyclic voltammograms, galvanostatic charge–discharge tests and electrochemical impedance spectroscopy (EIS). The rod-like LiV3O8 calcined at 500°C has the optimal performance, delivering an initial discharge capacity of 273.6 and 250.4mAhg−1 between 2.0V and 4.0V at a current density of 50 and 120mAg−1, respectively. After 60 cycles by applying 50mAg−1, a discharge capacity of 213.0mAhg−1 is obtained, showing a good cycling performance. The EIS studies show that the 500°C-LiV3O8 electrode has very low impedance increase during 1st to 240th discharge-charge cycles. All these results indicate that the rod-like LiV3O8 compound has a promising application as the cathode material for rechargeable lithium batteries. [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]