In this work, on the basis of a universal technological approach, the basis of which is the condensation of steam with low relative supersaturation, porous micro- and nanosites of Zn and Cu were obtained, which were subsequently used as precursors for obtaining a layer of porous turbostatic porous graphite, as well as porous systems NiO, ZnO and Si.
The literature review of the dissertation describes the features of using different types of materials as anodes for lithium-ion batteries. The analysis of literary sources showed that graphite, widely used as electrodes, allows intercalation of only one lithium ion in six carbon atoms, which corresponds to a theoretical equivalent capacity of 372 Ah/kg. In addition, the diffusion rate of lithium in the carbon material is from 10-12 to 10-6 cm2/s (for graphite it is in the range of 10-9 to 10-7 cm2/s), which creates prerequisites for a low power of LIB. Therefore, there is an urgent need to replace graphite anodes, or to improve their structure in order to increase the capacity and specific power, which can also provide high performance and facilitate the diffusion of Li-ions into the anode while maintaining reproducible cycles.
The second chapter describes the technological approaches to obtaining porous micro- and nanosystems on different types of substrates, and also provides the principle of operation of the developed installation. Since the formation of porous metal systems is possible only under the condition of using a highly pure inert medium (Ar), in the work, considerable attention was focused on the purification of argon from chemically active gas impurities. In this regard, a vacuum working chamber of the BSA-350 installation was used together with a fine purification system for inert gases.
A developed and patented technological approach of near-equilibrium condensation in a hollow cathode was used to obtain porous turbostrat graphite with different morphological characteristics. At the same time, acetone vapor was used as the working gas medium. It was demonstrated that the selectivity of the spatial distribution of the nucleation and growth of columnar graphite structures is determined by the fluctuation of the electric field intensity over the growth surface.
Based on the fact that when creating LIB and gas sensors, as a rule, multilayer systems were used, there was a need to solve the problems of adhesion and cohesion of condensates. In the work, adhesion and cohesion problems were solved in three ways. The first of them consisted in the use of substrates made of laboratory glass and sital with an unpolished rough surface. The problems of adhesion and cohesion were also solved thanks to the use of chrome layers, and the third option for solving the problem of cohesion during the formation of composites was solved by a gradient transition from one layer to another.
The third section contains information on nanosystems based on Zn, ZnO and ZnO/NiO for the use of the latter as active elements of gas sensors. The formation of porous ZnO/NiO nanosystems is presented in the work in the form of three stages: a) under the condition of condensation of zinc vapor with ultralow supersaturation, the formation of nanosystems in the form of interconnected nanothreads was carried out; b) oxidation on the obtained Zn nanosystems; c) application of a NiO film on the obtained ZnO nanosystems by the reactive method. At the same time, oxidation-resistant ITO films were used as electrodes, which were ohmic in relation to ZnO nanosystems. The sensory properties were investigated in relation to methane and methanol, and the type of the indicated reagents was determined by determining the changes in the character of the current-voltage characteristics (CVC) with the involvement of automated systems and using the commercial LabView software. At the same time, the characteristic changes of the C-V characteristic during the transition from methanol to methane indicate the fractal-percolation nature of ZnO/NiO nanosystems and the possibility of recognizing different reagents.
In the fourth, final chapter, the structural and morphological characteristics and results of using such porous nanosystems as ZnO, Zn/ZnO, Zn/C, Ni/C, Si and Cu/Si+W as LIB electrodes were investigated. Studies of charge-discharge cycles using porous nanosystems based on ZnO, Zn/ZnO as electrodes and solvents LiPF6 and LiBF4 show that, depending on the structural and morphological characteristics, elemental composition and number of cycles, the battery capacity factor varies from 800 to 218 Ah/kg. A comparative analysis of the work of electrodes based on the Cu/Si and Cu/Si+W systems allowed us to conclude that silicon based on lower oxidation resistance without the addition of tungsten and, as a result, significantly higher capacities (320÷450 Ah/kg) of electrodes based on Cu/ Si+W.
