The thesis deals with the development of scientific foundations for the for-mation of nanoscale and surface-modified electrode materials and their use in lithi-um-ion batteries (LIB) of high power and capacity. In it, for the first time, the rela-tionship between nanoscale and the degradability of electrode materials, the effect of nanostructuring on the properties of electrode materials, and the possibility of increasing the power of electrode materials by modifying the surface are considered.
For electrode materials of the LiNiyMnzCo1-y-zO2 composition with a layered structure, it is found that the transition of Li1.2Ni0.2Mn0.52Co0.08O2 to the nanoscale state makes it possible to achieve theoretical values of the specific capacity. Doping Li1.2Ni0.16Co0.08Mn0.54O2 with vanadium increases its specific capacity and cycling efficiency. LiNi0.83Co0.12Mn0.05O2 in the form of single, non-agglomerated crystals demonstrates better high current discharge capability than its commercial counter-part.
For nanosheets and microspheres of ТіО2 and openwork quasi-spherical ag-gregates of LiMn2O4, in comparison with nanocrystalline samples, it is found that nanostructuring is not a means of increasing the ability of electrode materials to be exposed to significant current loads.
For the first time, differences are noticed in the electrochemical properties of conventional and nanoscale electrode materials under overdischarge conditions (in-troduction of an excess of Li+ into the structure), and the ways of superlithiation reactions are determined. A conclusion is made about the decisive role of a decrease in the particle size in the interaction of electrode materials with lithium ions and in a decrease in their resistance to degradation. This proves the inadmissibility of the practical use of nanoscale electrode materials under overdischarge conditions.
It has been proven that the regulation of the surface state significantly increas-es the productivity of electrode materials. Thus, coating Li1.2Ni0.13Co0.13Mn0.54O2 with aluminum oxide makes it possible to increase the specific capacity of the mate-rial. The LiNi0.5Mn1.5O4@LiMn2O4 and РРу@LiMn2O4 structures are obtained for the first time, for which surface modification allows achieving ultrahigh discharge currents (65 C and 300 C, respectively). This approach opens up prospects for the creation of materials for LIBs of ultrahigh power, comparable to the power of su-percapacitors.
Using the РРу@LiMn2O4 composite as an example, the contribution of pseu-docapacitance effects to the intercalation process is discovered and a method is proposed for the first time to estimate the depth of lithium-ion penetration into the electrode material.
The advantages of water-soluble binders over the commonly used poly(vinylidene fluoride) have been proved, in particular, the possibility of achiev-ing an increase not only in the specific capacity, but also in the power of LIB when using them, due to the better adhesion of the electrode material to the surface of the current collector, has been noted for the first time.
Key words: lithium-ion batteries, high power, high capacity, nanodimensional-ity, nanostructuring, surface modification.
