Brogioli, Doriano
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Brogioli, Doriano
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Brogioli, Doriano
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Brogioli, D.
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Item-typ:Veröffentlichung, Dynamic Impedance Spectroscopy of Nickel Hexacyanoferrate Thin Films(2019-10-31); ; ; Dynamic multi-frequency analysis (DMFA) is capable of acquiring high-quality frequency response of electrochemical systems under non-stationary conditions in a broad range of frequencies. In this work, we used DMFA to study the kinetics of (de-)intercalation of univalent cations (Na+ and K+) in thin films of nickel hexacyanoferrate (NiHCF) during cyclic voltammetry. For this system, the classic stationary electrochemical impedance spectroscopy fails due to the instability of the oxidized form of NiHCF. We are showing that such spectra can be fitted with a physical model described by a simple two-step intercalation mechanism: an adsorption step followed by an insertion step. The extracted kinetic parameters are depending on the state of charge as well on the nature of the inserted cation.Wissenschaftlicher ArtikelBand:6Heft:21268 324 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Dynamic Impedance Spectroscopy: Fitting Multivariate Impedance Spectra using B-Spline BasisClassical approaches to modelling dynamic or multivariate impedance spectroscopy data rely on either fitting individual spectra using an iterative procedure or using a joint least-squares analysis combined with partial prior knowledge of the model as a function of parameters which show a dependence on a control variable such as voltage or time. However, these approaches often fail to provide accurate results due to their sensitivity to the initial guess of the model parameters and the lack of an adaptive modelling approach. We address these limitations by introducing an approach that combines the parametric modelling of single spectra and use cubic B-splines to introduce the dependence of such parameters on the control variable. We illustrate our method by analyzing a set of 50 spectra obtained from dynamic impedance studies of electron transfer involving a redox couple in solution. We further demonstrate that the spline-based method is less sensitive to initial guesses, outperforms classical fitting methods in preserving the model parameters’ dependence on the control variable and yields a significantly lower weighted residual mean square value compared to classical approaches.Konferenzbeitrag37 69 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Transition state theory in systems of interacting particles(2018-12-19); Chemical equilibrium is fully characterized at thermodynamic level by the free energy: the equilibrium is written in terms of equality of chemical potentials. Rate of chemical reactions can be calculated for ideal solutions by using mass-action equations, with reaction rate constants related to energy barriers through the transition state theory. The two approaches merge in the case of equilibrium and ideal solutions. Here, we discuss how to extend the transition state theory in the case of non-ideal solutions, i.e. of interacting particles, at equilibrium. We find bounds of the exchange reaction rate. However, we show that the value of the exchange reaction rate cannot be calculated from equilibrium thermodynamic parameters (i.e. from the free energy), i.e. it is possible to find different Hamiltonians giving the same free energy but different exchange reaction rate.Bericht221 117 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Innovative technologies for energy production from low temperature heat sources: critical literature review and thermodynamic analysisThe scientific community has taken on the challenge to develop innovative methods to exploit low-temperature (<100 °C) heat sources, having large potential to decrease the carbon footprint. In this review, we first summarise the novel proposed techniques, and then we propose a framework for comparing the performances reported in the literature based on two indices, which are currently critical for the technical and economic feasibility: energy efficiency and power density. Two techniques show the best performances; both use distillation to regenerate the working solution of a flow battery. In many papers, schemes based on additional heat exchangers are proposed with the aim of improving the efficiency. Such techniques are also discussed here: first, the power per unit surface of the heat exchangers is discussed as a performance index; then, a method for inherently ranking the techniques, independent of the use of additional heat exchangers, is provided. The analysis shows that the application of such schemes does not significantly change the ranking of the techniques, while having a detrimental effect on the complexity of the whole system. Finally, we discuss the performances of the various techniques based on general thermodynamic principles and methods; in particular, the meaning of the temperature versus entropy graph in this context is considered.Wissenschaftlicher ArtikelBand:14Heft:331 63 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Lithium recovery from diluted brine by means of electrochemical ion exchange in a flow-through-electrodes cellLithium is becoming an important raw material due to the expansion of the market of lithium-ion batteries, required for electric vehicles and for stationary energy storage. The current method of lithium extraction is slow, inefficient and it has a strong environmental impact. In the last decade a new technology, called “electrochemical ion pumping”, based on the electrochemical selective capture of lithium cations from the brine, followed by the release of the ions into a so-called “recovery solution”, was proposed. In this work, we developed a flow-through-electrodes reactor, with which it was possible to capture lithium from a diluted solution containing 1 mM LiCl and 1 M NaCl, and concentrate it in a recovery solution. After 9 cycles, it was possible to produce 5 mL of 100 mM LiCl solution with 94% purity starting from more than one liter source solution. We have estimated the energy required by the process, finding that the major contribution is given by the hydraulic energy for pumping the electrolyte through the cell. The evaluation shows that the technology is economically feasible and it can enable a sustainable future production of lithium.Wissenschaftlicher ArtikelBand:47535 77 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Dynamic impedance spectroscopy of LiMn2O4 thin films made by multi-layer pulsed laser deposition(2020-01-20); ; ; ; The kinetics of the reversible insertion of lithium ions assisted by aqueous environment into thin film fabricated by multi-layer pulsed laser deposition is studied using dynamic multi-frequency analysis (DMFA). This method allowed us to acquire time resolved impedance spectra in the range of 210 kHz to 11.5 Hz during cyclic voltammetry. The impedance spectra obtained comprises of two RC time constants (semi-circles) indicating that the reversible insertion process of lithium ions in thin films in aqueous media follows a two-stage intercalation process with the first stage as the (de)solvation step of the lithium ions and the second stage as a (de)insertion process with a concurrent change in the oxidation state of manganese. The temporal development of the kinetic parameters with the state of charge during the voltage sweep was investigated and reported in this work.Wissenschaftlicher ArtikelHeft:331313 454 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Thermally Regenerable Redox Flow Battery(Wiley, 2020-08-24); ; ; ; The efficient production of energy from low-temperature heat sources (below 100 °C) would open the doors to the exploitation of a huge amount of heat sources such as solar, geothermal, and industrial waste heat. Thermal regenerable redox-flow batteries (TRBs) are flow batteries that store energy in concentration cells that can be recharged by distillation at temperature <100 °C, exploiting low-temperature heat sources. Using a single membrane cell setup and a suitable redox couple (LiBr/Br2), a TRB has been developed that is able to store a maximum volumetric energy of 25.5 Wh dm−3, which can be delivered at a power density of 8 W m−2. After discharging 30 % of the volumetric energy, a total heat-to-electrical energy conversion efficiency of 4 % is calculated, the highest value reported so far in harvesting of low-temperature heat.Wissenschaftlicher ArtikelBand:13Heft:2035 61 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Review of Power Converter Topologies for Electrochemical Impedance Spectroscopy of Lithium-Ion Batteries(IEEE, 2022-10-17); ; ; ; Frequency domain impedance of Li-ion batteries contains valuable information about the state of charge (SOC) and state of health (SOH). Normally, electrochemical impedance spectroscopy (EIS) is performed during the relaxation of battery cells. However, performing EIS during the batteries operation has been achieved through switching power converters. This paper reviews the power converter topologies for both online and offline Electrochemical Impedance Spectroscopy (EIS) characterization of batteries. The information that can be extracted from EIS Nyquist plots are discussed. Comparative analysis between converter topologies is presented. Finally, challenges are identified and new converter topologies are proposed for further consideration in online/offline EIS characterization.Konferenzbeitrag32 74