Pidluzhna A. Lithium intercalation of chemically modified and defective low-dimensional materials.

The Candidate's degree thesis on speciality 02.00.04 - physical chemistry. Yuriy Fedkovych Chernivtsi National University, Chernivtsi, 2014. The results of systematic studies of processes of lithium intercalation in chemically modified and defective low dimensional cathode materials for lithium power sources are presented. As it was experimentally determined, the transition to nanoscale particles of host-matrixes significantly changes the characteristics of the lithium intercalation process. The nature of these changes depends on the type of matrix. So, for bismuth selenide, the specific capacity and Gibbs energy change of the lithium intercalation is doubled for all values of the guest load degree, and the order of coefficient of lithium diffusion increases on 4 units. The switch to nanoscale particles of leads to energy spectrum discretization and an increase in specific capacity up to 1800 mAh/g for the average particle size of silicon dioxide of 9 nm. The decrease of particle size of titanium dioxide with some impurities down to 100 nm leads to the increase in specific capacity from 300 to 2300 mAh/g at discharge down to 1.5 V and the increase in the coefficient of lithium diffusion twice. The purposeful doping of nanoparticles leads to a change of its phase composition and size and, consequently, to a change in specific capacity of cathode material of lithium power sources. The effect of change depends on the nature of the dopant agent and its amount. So, titanium dioxide doped by iron in 2 and 5% (weight) can increase the specific capacity on 100 mAh/g. The doping of talc leads to changes in the thermodynamic and kinetic parameters of lithium intercalation by modification of structural and electronic properties of the host matrix. The contribution of the transformation of the impurity energy spectrum is dominated and may not correlate with the degree of structural change. The laser irradiation of the non-metallic phases with photon energy less than the band gap of these materials is an effective way to control kinetic and energy parameters of lithium intercalation in them. It was established that the effect of laser irradiation depends on the size of particles of irradiated material.