Improved Li-Storage Properties of Cu2V2O7 Microflower by Constructing an in Situ CuO Coating

As an anode material for lithium ion batteries, metal vanadates undergo structure variation in the lithiation process. In the case of copper pyrovanadate (Cu2V2O7), it would decompose to be amorphism after the first deeply discharge process (cutoff voltage <= 1.5 V). This single-pass process leads to an abrupt capacity fading and poor electrochemical performance. In this paper, a novel CuO coated Cu2V2O7 microflower (Cu2V2O7@CuO) is first synthesized by a facile hydrothermal-heat treatment. The CuO not only relieves the single-pass reconstruction of Cu2V2O7 in the initial discharge but also elevates the Li+ diffusion kinetics in the cycle process via the heterointerfaces. And thus, the Cu2V2O7@CuO microflower displays a reversible capacity of 662.9 mAh g(-1) at 100 mA g(-1) after 100 cycles. Even at a high rate of 5000 mA g(-1), the as-product exhibits an excellent capacity of 220 mAh g(-1). These results show that constructing an in situ coating is a worthwhile modification method for improving the electrochemical properties of metal vanadates.