Ústav elektrotechnologie

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Mathematical Physics Analysis of Nozzle Shaping at the Gas Outlet from the Aperture to the Differentially Pumped Chamber in Environmental Scanning Electron Microscopy (ESEM)
(MDPI, 2024-05-20) Maxa, Jiří; Neděla, Vilém; Šabacká, Pavla; Binar, Tomáš
A combination of experimental measurement preparations using pressure and temperature sensors in conjunction with the theory of one-dimensional isentropic flow and mathematical physics analyses is presented as a tool for analysis in this paper. Furthermore, the subsequent development of a nozzle for use in environmental electron microscopy between the specimen chamber and the differentially pumped chamber is described. Based on experimental measurements, an analysis of the impact of the nozzle shaping located behind the aperture on the character of the supersonic flow and the resulting dispersion of the electron beam passing through the differential pumped chamber is carried out on the determined pressure ratio using a combination of theory and mathematical physics analyses. The results show that nozzle shapes causing under-expanded gas outflow from the aperture to the nozzle have a worse impact on the dispersion of the primary electron beam. This is due to the flow velocity control. The controlled reduction in the static pressure curve on the primary electron beam path thus causes a significantly higher course of electron dispersion values than variants with shapes causing over-expanded gas outflow.
Impedance changes of the Liion cell in the course of discharge
(Springer, 2024-03-05) Křivík, Petr
The paper deals with the measurement of the cell impedance parameters during discharging of the Li-ion NCR18650B cell. Re (Z) and Im (Z) of the battery were measured by PEIS method. The results of the impedance changes during discharging and charging were plot to Nyquist diagrams. The important values namely Rs, Rsei, Rct, Csei, Qsei, Cdl, , and were found during discharging of the Li-ion cell with and without using CPE element.
Effect of pressing pressure on the capacity of recycled graphite anode
(SPRINGER WIEN, 2024-02-20) Báňa, Jiří; Čudek, Pavel; Šedina, Martin; Šimek, Antonín; Kazda, Tomáš
Due to the increasing demand for lithium-ion batteries, there is an urgent requirement for environmentally friendly and efficient means of recycling these batteries. Graphite, a readily available and cost-effective material, tends to be neglected compared to more expensive metals such as cobalt or nickel. To achieve the new European targets, it will be necessary to focus on recycling even less valuable materials, such as graphite. Direct recycling of graphite represents an environmentally and economically viable solution. However, the capacity of recycled graphite depends on several factors, with pressing pressure being a potential variable. Within this article, we have focused on the impact of pressing pressure of spent graphite anode. The recycling was performed on the battery sample with a known lifetime history. It was found that when optimized, it is possible to achieve high stability and high capacities exceeding 300 mAh/g.
Evaluation of the Thermal Energy Potential of Waste Products from Fruit Preparation and Processing Industry
(MDPI, 2024-01-26) Bača, Petr; Mašán, Vladimír; Vanýsek, Petr; Burg, Patrik; Binar, Tomáš; Suchý, Pavel; Vaňková, Lenka
In the context of a changing climate and increasing efforts to use renewable energy sources and waste materials and to green the environment, new sources and technologies for energy recovery from waste are being sought. This study evaluates the possibilities of energy generation potential from waste products of fruit species used in the food processing industry. The results indicate good potential for energy use of materials from fruit processing due to low input moisture content of around 15 wt. %, an average energy lower heating value (LHV) of 16.5 MJ·kg1, an average low ash content of 4.9% and meeting most of the emission limits of similar biofuels. Elemental analysis and combustion residue studies indicate safe operation within existing standards. The results of our analyses and experience from similar studies allow us to recommend most of the studied waste materials for energy generation use directly in processing plants at the local level.
A short review of the effect of external pressure on the batteries
(Springer, 2024-01-12) Šedina, Martin; Šimek, Antonín; Báňa, Jiří; Kazda, Tomáš
The research of the batteries is still going forward and there are lots of challenges which should be solved. This text examines the effect of external pressure on different types of batteries and explores their potential for improving performance and lifetime. The studies reviewed in the text show interesting results where external pressure affects capacity, internal resistance, stability or other parameters of modern battery systems as Li-ion, solid-state, or Li-S batteries. Despite the challenges, the benefits for next-generation batteries seem promising and show its role in battery development and manufacturing.

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