Microwave-Assisted Synthesis of Silver Vanadium Phosphorus Oxide, Ag<sub>2</sub>VO<sub>2</sub>PO<sub>4</sub>: Crystallite Size Control and Impact on Electrochemistry

Abstract

Silver vanadium phosphorus oxide, Ag<sub>2</sub>VO<sub>2</sub>PO<sub>4</sub>, is a promising cathode material for Li batteries due in part to its large capacity and high current capability. Herein, a new synthesis of Ag<sub>2</sub>VO<sub>2</sub>PO<sub>4</sub> based on microwave heating is presented, where the reaction time is reduced by approximately 100× relative to other reported methods, and the crystallite size is controlled via synthesis temperature, showing a linear correlation of crystallite size with temperature. Notably, under galvanostatic reduction, the Ag<sub>2</sub>VO<sub>2</sub>PO<sub>4</sub> sample with the smallest crystallite size delivers the highest capacity and shows the highest loaded voltage. Further, pulse discharge tests show a significant resistance decrease during the initial discharge coincident with the formation of Ag metal. Thus, the magnitude of the resistance decrease observed during pulse tests depends on the Ag<sub>2</sub>VO<sub>2</sub>PO<sub>4</sub> crystallite size, with the largest resistance decrease observed for the smallest crystallite size. Additional electrochemical measurements indicate a quasi-reversible redox reaction involving Li<sup>+</sup> insertion/deinsertion, with capacity fade due to structural changes associated with the discharge/charge process. In summary, this work demonstrates a faster synthetic approach for bimetallic polyanionic materials which also provides the opportunity for tuning of electrochemical properties through control of material physical properties such as crystallite size

    Similar works

    Full text

    thumbnail-image

    Available Versions