The primary objectives of this research are: (1) use a hierarchical structure to study electrode materials for next-generation lithium-ion batteries (LIBs) and (2) understand the fundamentals and utility of solid polymer electrolytes (SPEs) with the addition of halloysite nanotubes (HNTs) for battery applications. Understanding the fundamental principles of electrode and electrolyte materials allows for the development of high-performance LIBs. The contributions of this dissertation are described below. Encapsulated Si-VACNT Electrodes. Two hurdles prevent Si-based electrodes from mass production. First, bulk Si undergoes volume expansion up to 300%. Second, a solid-electrolyte interphase (SEI) forms between the interface of the electrolyte and electrode, which consumes battery capacity and creates more resistance at the interface. Si volume changes were overcome by depositing silicon on vertically-aligned carbon nanotubes (VACNTs). Encapsulating the entire Si-VACNT electrode surface with carbon was used to mitigate SEI formation. Although SEI formation was reduced by the encapsulation layer, capacity fade was still observed for encapsulated electrodes, indicating that SEI formation was not the primary factor affecting capacity fade. Additionally, the impact of the encapsulation layer on Li transport was examined. Two different transport directions and length scales were relevant””(1) radial transport of Li in/out of each Si-coated nanotube (~40 nm diameter) and (2) Li transport along the length of the nanotubes (~10 µm height). Experimental results indicated that the height of the Si-VACNT electrodes did not limit Li transport, even though that height was orders of magnitude greater than the diameter of the tubes. Simulation and experimental data indicated that time constant for Li diffusion into silicon was slow, even though the diffusion distance was short relative to the tube height. Other factors such as diffusion-induced stress likely had a significant impact on diffusion through the thin silicon layer. Solid Polymer Electrolytes. A thorough understanding of the relationships between physical, transport, and electrochemical properties was studied. HNT addition to polyethylene oxide (PEO) electrolytes not only improved the physical properties, such as reduction of the crystallinity of PEO, but also enhanced transport properties like the salt diffusivity. The processing steps were important for achieving enhanced properties. Moreover, HNTs were found to stabilize the interfacial properties of the SPE films during cycling. Specifically, HNT-containing SPE films were successfully cycled at room temperature, which may have important implications for SPE-based batteries.

The recent discovery of layered transition metal carbides (MXenes) is one of the most important developments in two-dimensional (2D) materials. Preliminary theoretical and experimental studies suggest a wide range of potential applications for MXenes. The MXenes are prepared by chemically etching ‘A’-layer element from layered ternary metal carbides, nitrides and carbonitrides (MAX phases) through aqueous acid treatment, which results in various surface terminations such as hydroxyl, oxygen or fluorine. It has been found that surface terminations play a critical role in defining MXene properties and affects MXene performance in different applications such as electrochemical energy storage, electromagnetic interference shielding, water purification, sensors and catalysis. Also, the electronic, thermoelectric, structural, plasmonic and optical properties of MXenes largely depend upon surface terminations. Thus, controlling the surface chemistry if MXenes can be an efficient way to improve their properties. This research mainly aims to perform surface modifications of two commonly studied MXenes; Ti2C and Ti3C2, via chemical, thermal or physical processes to enhance electrochemical energy storage properties. The as-prepared and surface modified MXenes have been studied as electrode materials in Li-ion batteries (LIBs) and supercapacitors (SCs). In pursuit of desirable MXene surface, we have developed an in-situ room temperature oxidation process, which resulted in TiO2/MXene nanocomposite and enhanced Li-ion storage. The idea of making metal oxide and MXene nanocomposites was taken to the next level by combining a high capacity anode materials – SnO2 – and MXene. By taking advantage of already existing surface functional groups (–OH), we have developed a composite of SnO2/MXene by atomic layer deposition (ALD) which showed enhanced capacity and excellent cyclic stability. Thermal annealing of MXene at elevated temperature under different atmospheres was carried out and detailed surface chemistry was studied to analyze the change in surface functional groups and its effect on electrochemical performance. Also, we could replace surface functional groups with desirable heteroatoms (e.g., nitrogen) by plasma processing and studied their effect on energy storage properties. This work provides an experimental baseline for surface modification of MXene and helps to understand the role of various surface functional groups in MXene electrode electrochemical performance.

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The thesis deals with liquid aprotic electrolytes based on mixtures of ionic liquid and solvent. EmimBF4, namely 1-ethyl-3-ethylimidazolium tetrafluoroborate, was used as the starting ionic liquid. A mixture of propylene carbonate, ethylene carbonate and dimethyl carbonate was used as solvents. Electrolytes were enriched with two electrolyte salts LiBF4 and NaBF4 from the resulting mixtures selected the most suitable electrolytes for Li-ion and Na-ion accumulators. Electrolytes were selected taking into account the required properties: the width of the potential window, the measured electrical conductivity and, last but not least, the safety.

This work is focused on lithium-ion batteries in general and their modeling capabilities in ANSYS Fluent. The various advantages and disadvantages of li-ion batteries are describes in my work. There are also described the various models and submodels offered by ANSYS Fluent. An essential part of the work is to model the real battery and compare the results between the real battery and the simulation itself. Finally, simulation of battery breakdown is performed.

The main aim of this paper are models of Li-Ion storage batteries made and simulated in ANSYS Fluent software. Various ways of simulations are discussed with main aim on ECM method and how its numerical model is computed. A process of getting information and required data from real battery to be compared with simulation results by EIS method is also discussed. These results are then compared with results from ANSYS Fluent.

Thesis deals with the design of a battery box with lithium-ion technology, for the largest possible driving range of the BUT SuperEL II electric car. Based on the analysis of the electric vehicle available space and the parameters of the electronic system, the maximum size of the entire set of 84s130p batteries was designed. 18650 cells with NMC technology were selected due to the very high gravimetric and volumetric density, which reaches 274 Wh/kg and 564 kWh/m3. The total nominal capacity of the designed battery boxes in the electric car is 138 kWh. The total gravimetric energy density of the designed box is 215.6 Wh/kg. It allows the electric car to reach the theoretical range with a consumption of 14 kWh/100 km of almost 1000 km. The individual battery modules of the battery box are controlled for optimal operating conditions by means of a BMS. The whole set is divided into 5 battery boxes. These boxes are manufactured using the technology of bent welded sheets from aluminum alloy EN AW 1050A and steel 1.4301. FEM analyzes were performed to verify the mechanical strength of the designed structure. The work also deals with the design of battery modules and their connection.

The master's thesis is devoted to the comparison of different types of lithium-ion batteries. Primarily, an introduction to electrochemical power sources and their division is described. Furthermore, the thesis deals only with lithium-ion batteries. In the theoretical part, the chapters discuss the history, the principle of operation and a detailed description of the main battery parts, including used materials. A comparison of commercially available lithium-ion cells with each other as well as with other types of batteries is also included in the theoretical part. The practical part deals with the cyclinf of lithium-ion cells and subsequent evaluation of the effect of temperature on the capacitance and current characteristics of these lithium-ion batteries.

This work is focused on Li ceramics and glass-ceramics with low thermal expansion. Composition of these material is based on mineralogical composition of ?-spodumene – Li2O•Al2O3•4SiO2. Sol-gel route of preparation was used for preparation of the material. Sol-gel route is profitable because of production of high purity and controlled grain size powder. Lower sintering temperature, higher degree of homogeneity and shorter time of heat treatment in comparison with traditional approach belong among other advantages of sol-gel route of preparation. Influence of Li+ substitution for K+, which has similar atomic radius, is assessed in this work. These ions are localized in the interstitial position of spodumene structure and are able to maintain the charge balance. Li+ ions were substituted with K+ in the amount of 0; 0,5; 1; 2; 5 and 10 wt. % in view of Li+ weight. In the next step influence of adding mineralizer was specified in the material modified this way. The effect of adding mineralizer on phase transformation and heat treatment tendency was considered. K+ were added to the mixture in the form of potash. Due to this addition forming of orthoclase phase next to spodumene, eucryptit and SiO2 (ss) was detected. Decrease in melting temperature and ability of melt to crystallize were consequence of orthoclase forming. No crystallization appears, when more than 1 wt.% of K+ was added.

My master thesis is focused on intorducing, analysing and describing the microprocessor controlled charger. The thesis is firstly describing and analysing the topic of accumulator cell charging for common technologies. Than there is detailed description of specific accumulator cell types (NiMH, NiCd and Li-ion) which is the microprocessor controled charger intend for. The next part of this thesis is showing the proposal of the charger. There is the block diagram, charger detailed schematics based on this block diagram. There is also list of the possible useful componets neccessary for charger assembling. All this is used for the final proposal of the chager itself. The main scope of this thesis is than the charger's microcontroler firmware decribed at the end of this thesis. Finaly confirmation of the charger proper proposal and assembly is the battery charging with the given basic parameters.