The synthesis, structure, and electrochemical properties of a novel rods-shaped Li6V10O28 for lithium-ion batteries

Abstract

Rods-shaped Li 6 V 10 O 28 powders were synthesized by rheological phase reaction. The ratio of the Li/V of the product sintered at 600°C for 8 h was characterized by inductively coupled plasma. The structure, composite, and morphology of the product have been investigated by X-ray diffraction, scan electron microscope, transmission electron microscopy, and X-ray photoelectron spectrometry, respectively. After charge-discharge test using the product as the cathode material of lithium-ion batteries, the product calcined at 600°C for 8 h exhibited an initial high discharge specific capacity of 212.4 mAh/g at a rate of 1.0 mA/cm 2 in a potential range of 2.0 and 4.4 V, and its stabilized capacity still remained 167.7 mAh/g after 30 cycles, which indicates that the rods-shaped Li 6 V 10 O 28 are promising cathode materials in lithium-ion batteries.

Differentiating Molecular and Solid‐State Vanadium Oxides as Active Materials in Battery Electrodes

“…Virtually identical data to the data reported here for 1 – 400 has recently been presented in the literature and was assigned to the performance of the molecular decavanadate Li 6 V 10 O 28 . Here we show, that in fact, the behaviour is associated with solid‐state lithium vanadate phases and is not related to a molecular POV‐based battery electrode.…”

“…This is consistent with the removal of 16 water molecules from 1 (calcd: 22.3 wt.‐%) and illustrates that due to the strong hydrogen bonding, temperatures significantly higher than the boiling point of water are required for full dehydration of 1 . This also explains previous literature reports, which used temperatures higher than 240 °C for dehydration of 1 before LIB electrode fabrication . Note that inductively coupled plasma optical emission spectroscopy (ICP‐OES) analysis of the dehydrated compound 1 gave a Li/V atomic ratio of 6.1 : 10, in line with the expected stoichiometry for 1 .…”

“…This also explains previous literature reports, which used temperatures higher than 240°C for dehydration of 1 before LIB electrode fabrication. [11] Note that inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis of the dehydrated compound 1 gave a Li/V atomic ratio of 6.1 : 10, in line with the expected stoichiometry for 1.…”

“…The electrochemical properties of 1-120 and 1-400 were investigated to compare their behavior with earlier reports, which claimed to use POVs as battery electrodes but used very similar electrode fabrication methods as described above, so that solid-state oxide formation could not be excluded. [7][8][9][10][11] Galvanostatic charge/discharge profiles vs lithium (at a current density of 50 mA/g in the voltage range of 1.2 V -4.0 V (vs. Li + /Li)) show significant differences between both samples: 1-120 shows sloping charge/discharge curves and no plateau, suggesting a solid solution system with an initial specific discharge capacity of 288 mAh/g ( Figure S5, SI). [31] The data are in line with a previous study, which reported virtually identical data but suggested that the performance is based on the molecular decavanadate 1.…”

“…400 mAh/g) but low cycling stability while samples treated at 600 °C showed lower initial specific capacities (ca. 200 mAh/g) but high cyclability which may due to higher crystallinity of the product formed at higher temperatures . Further, the thermally dehydrated decavanadate salt Na 6 [V 10 O 28 ] was recently reported as anode material with high cycling stability in sodium ion batteries (NIBs) .…”