Construction of needle-like crystalline AgO ordered structures from Ag nanoparticles and their properties

Abstract

AgO has wide applications in various fields such as in catalysis, sensing, electrochemistry, and especially energy storage. The well-ordered structures of electrode materials are important for high energy density batteries to improve ion transport and charge transfer abilities, which will result in better electrochemical performances. However, to date, only few studies have been reported on the construction and property of a well-ordered AgO array and its related applications in electrodes and batteries. In this study, highly ordered arrays of needle-like structured silver oxide crystals were constructed for the first time by electro-induced oxidation of Ag nanoparticles in an aqueous solution. It was found that the structures and orientations of the AgO crystal were closely related to the electric current direction and density. Furthermore, the as-prepared AgO array was used as a cathode to assemble an Al/AgO battery in the present study. The electrochemical examinations revealed that the battery with highly ordered needle-like structured AgO formed by the plane contact electro-oxidization method showed a lower R_ct, better reduction ability, as well as an amazing specific capacity (426.9 mA h g⁻¹ at 3C rate), which was 98.8% of the theoretical value (432 mA h g⁻¹) and a 44.8% improvement over the conventional industrial electro-formed sintered type AgO electrode. This kind of highly ordered arrays of needle-like structured silver oxide crystals could efficiently accelerate the transport of electrolytes and electrons, resulting in a better discharge ability. The study provides a new method to construct a well-ordered array of needle-like structured silver oxide crystals and illustrates the great advantages of the unique structure.