Operando Structural and Electrochemical Investigation of Li1.5V3O8 Nanorods in Li-ion Batteries

We report facile solvothermal synthesis of submicron (sub-micrometer)-sized rod-like Li1.5V3O8 crystals using a mixture of ethylene glycol/water as the reacting media. The crystal structure and morphology of the resulting compound were characterized by Rietveld refinement, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and thermal analysis (TG/DTA). Rietveld analysis confirms monoclinic Li1.5V3O8 crystals with P2(1)/m symmetry having a monodispersed similar to 5 mu m long and similar to 500 nm thick rod-like morphology. As the cathode in Li-ion batteries (LIBs), Li1.5V3O8 nanorods deliver a reversible discharge capacity of similar to 239 mAh g(-1) in the voltage window of 2.0-4.0 V (vs Li/Li+) at a 0.1 C rate after 50 cycles. Li1.5V3O8 nanorods retain an impressive discharge capacity of similar to 161 mAh g(-1) after 250 cycles at a 1 C rate. Operando (in-situ) XRD investigation of Li1.5V3O8 during electrochemical (dis)charging confirms the phase transformations from a Li-poor alpha-phase (Li-1) via a Li-rich alpha-phase (Li-2.5) to a beta-phase (Li-4). Low-temperature performance evaluation of the Li(1.5)V(3O)8 cathode exhibits less than 50% of the discharge capacity achieved at 25 degrees C. Evaluation of dis(charge) behavior over different temperatures suggests that charge transfer resistance (Rct) plays a crucial role in determining Li-ion diffusivity vis-a-vis specific capacity at low-temperature.