Phase transformations in CoZnO/CoZn nanostructures depending on the difference in applied potentials

Abstract

The dynamics of phase transformations in CoZnO/CoZn nanostructures of the Zn – Hexagonal/ZnCo2O4 – spinel → Zn – Hexagonal/Co2.34Zn10.63 → Co– Hexagonal/Co2.34Zn10.63 type depending on the difference of the applied potentials is presented. As a production method, the method of electrochemical synthesis was used, in which polymer track membranes with pore diameters of 400 nm and a length of 12 μm were used as templates. The study found that at small potential differences (1.25–1.75 V), the presence of oxygen is observed in the structure of nanowires, which is introduced into the crystalline structure during the synthesis. In this case, an increase in the difference in the applied potentials above 1.75 V leads to an increase in the cobalt concentration in the structure of the nanowires accompanied by the displacement of oxygen and the formation of the Co/Zn structure with a stoichiometric ratio of 1:1. It was found that all the nanostructures under study during the life tests of the applicability of these nanostructures as cathode materials of lithium-ion batteries retained their operability after 400 cycles of life tests, which indicates their high resistance to degradation. Moreover, for samples containing a high concentration of cobalt in the structure, the lifetime reaches more than 800 cycles, which is explained by the high stability of these nanostructures to degradation processes.