Binary metal oxide anode material, VOMoO4/C, with a high capacity and ultralong cycle-life for lithium ion batteries and its multi-electron reaction mechanism

Abstract

To explore novel electrode materials with a high energy density for lithium ion batteries, VOMoO4/C was successfully synthesized via a simple sol–gel method. VOMoO4 exhibits excellent electrochemical performance owing to the multi-electron reaction of V and Mo, constructing a competitive material respect to traditional graphite anode material. At a current density of 0.2 A g−1, the VOMoO4 sample electrode delivers a high specific capacity of over 830 mA h g−1 after 250 cycles. Moreover, the VOMoO4 sample shows high and stable capability even at an extreme current density of 10 A g−1. Using CV, EIS and V/I methods, we discussed the origin of the higher reversible cycling capacity and superior rate performance. To explore the reversible discharge/charge process, using In-situ XRD (X-ray diffraction) and Ex-situ XPS (X-ray photoelectron spectroscopy) experimental results, we discuss the complex conversion reaction mechanism of VOMoO4 in detail for the first time. Due to the multi-electron reaction of V and Mo, VOMoO4 reversibly transfers a total of 9 mol Li+ during the reversible insertion/extraction process, providing a high specific capacity of 1062.9 mA h g−1. Considering its superior high reversible capacity, long-term cycling stability and outstanding rate capability, VOMoO4/C is an ideal candidate as an alternative to traditional graphite anode material for lithium ion batteries.