STUDY OF THE PROCESS OF OBTAINING A COMPOSITE MATERIAL "SPHERICAL GRAPHITE – Fe2O3"

Abstract

In this article, a study was conducted on the process of obtaining a composite material “spherical graphite – iron oxide”, with the aim of its further use as an anode material for lithium-ion batteries. The composite was obtained by depositing iron oxide nanoparticles on the surface of spherical graphite. The influence of the deposition process parameters on the physico-chemical properties of the composite has been studied. It was found that the following factors have a significant effect on the final properties of the composite: the nature of the precipitator, the density of graphite loading of the precipitation working solution, the aging time of the system, the ratio of di- and trivalent iron in solution. Solutions of ammonia and urea were studied as precipitators. In the case of using urea, the formation of iron oxide particles with smaller coherent scattering regions, that is, with smaller crystallite sizes, was noted. Amorphous Fe2O3 precipitates are more preferable in terms of using them as an anode material. With an increase in the loading density of the graphite deposition solution, an increase in the yield of iron oxide nanoparticles was observed, however, at loading densities above 15 g/l, large iron oxide aggregates were formed. With an increase in the aging time of the deposition system, an improvement in the distribution of iron oxide nanoparticles over the surface of spherical graphite and a decrease in nanoparticle aggregates were noted. An increase in the molar fraction of Fe2+ in the precipitation solution has a similar effect. Based on the experimental data obtained, the optimal modes of the iron oxide deposition process were determined. Under these conditions, a sample of spherical graphite coated with Fe2O3 nanoparticles with average particle sizes of 30-50 nm was obtained. The oxide content in the sample was 3.7%. Electrochemical studies of the lithium-ion battery layout have shown that spherical graphite modified with iron oxide shows a reversible capacity increased to 370 mA∙h/g and greater stability of work.