Conductive surface modification of cauliflower-like WO3 and its electrochemical properties for lithium-ion batteries

Cauliflower-like WO3 was synthesized by a hydrothermal reaction without a surfactant, followed by firing, and was investigated as an anode material for lithium-ion battery applications. The scanning electron microscope (SEM) and transmission electron microscope (TEM) characterization indicated that WO3 nanorods had an aggregation framework and built a cauliflower morphology. With the objective of understanding the charge-discharge process within a voltage range of 0-3 V vs. Li+/Li, in situ X-ray diffraction was used and a complex reaction of intercalation and conversion of WO3 was revealed for the first time. The cauliflower-like WO3 after being decorated with carbon provides a high gravimetric capacity of >635 mA h/g (Li5.5WO3) with good cycling and a high rate capability when used as an anode in lithium-ion batteries. Based on our studies, we attribute the high electrochemical performance to the nanoscopic WO3 particles and a conductive carbon layer, which makes them a potential candidate for lithium-ion batteries.