Gasyuk I. Synthesis and physico-chemical properties of the lithium power sources cathode material based on the complex iron-containing oxides.

A comprehensive investigation of the physicochemical characteristics of the lithium power sources cathode material based on the complex iron-containing oxides is carried out in the thesis. For the first time systems of experimental current sources with cathodes based on iron-containing spinel modified by iso- and heterovalent ions have been implemented.It is shown that high intercalation Li+ parameters of LPS iron-containing cathodes are provided by the existence of spatially separated regions in the cathode with different types of conductivity (ionic and electronic), forming of which is provided by the formation of hard-colloidal system from spinel matrix perfect grains, which exists in the developed grid of grains boundaries, formations of other phases and mesostructural intergrains units obtained from substitutions and synthesis treatment. Quasi-equilibrium synthesis conditions enhance the contact of high ionic conductivity areas, and hence Li+ electrostimulated diffusion in the whole volume of grain.Kinetic model of lithium electrochemical intercalation in the cathode system is experimentally substantiated. It was found out that blocking of lithium intercalation the grain volume of spinel phase is caused by low values of diffusion coefficient and its decreasing dependence on the cathode-anode potential difference, and the benefit of priority lithium filling of tetrahedral coordinated guest positions in spinel with the following phase transformation of the surface areas of intercalation compounds.The existence of mesoscopic structures in spinel phase of aluminum-substituted lithium iron ferrite, which is manifested in the presence within a single grain of spatially separated regions of the ferrite existence, enriched or depleted by iron and substitution element.For the first time it was shown that the formation of ion-and electron-transport system is possible in a single proposed cycle of the material ceramic synthesis. Operating parameters of LPS laboratory samples on synthesized cathode are defined.