Fachgebiet 31: Energiespeicher- und Energiewandlersysteme
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Item-typ:Veröffentlichung, Towards the commercialization of rechargeable aqueous zinc ion batteries: The challenge of the zinc electrodeposition at the anodeThe low efficiency of the electrodeposition of metallic zinc from mild-acidic electrolytes in realistic operating conditions currently represents the main challenge hindering the commercialization of aqueous Zn-ion batteries (ZIBs). These devices offer good environmental compatibility, low production costs, and high powder densities, thus are considered as a viable energy storage solution for stationary applications. The electrodeposition of metallic zinc is generally affected by dendrites, spontaneous evolution of gaseous hydrogen, and precipitation of insulating passivation products on the electrode surface. The recent scientific literature has provided many strategies addressing the zinc electrodeposition through the optimization of the electrode, of the aqueous electrolyte, or of the electrode–electrolyte interface. However, industrially relevant requirements such as realistic values of anode usage, current densities, and capacity limits, must be implemented in the future research studies.Wissenschaftlicher ArtikelBand:3852 74 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Self-discharge in Li-ion aqueous batteries: A case study on LiMn2O4(Elsevier Science, 2021-03-20); ; ; ; Aqueous rechargeable lithium-ion batteries have attracted great attention as an alternative to traditional battery technologies, being able to overcome the issues caused by flammable and expensive organic electrolytes. In particular, LiMn2O4 has reached very fast second-level charge capability by the synthesis of unconventional morphology and particle sizes, allowing charging rates up to 600 C and 93% retention of the capacity after 10,000 cycles. However, the self-discharge process and aging mechanisms for aqueous batteries have been rarely studied, which contrasts with the extensive bibliography of the same phenomena in LMO cells based on organic electrolytes. In this article, the mechanisms involved in the loss of reversible specific charges were studied by diverse techniques like OCV, EIS, and In-situ Raman. The results revealed a more favorable self-discharge process compared with using organic electrolytes owing to the lower stability of water. The self-discharge process can be divided into three different regions with a sequential lower decay rate of voltage and capacity as well as two different evolutions of the electric parameters. This study opens new questions about the nature, composition, and mechanisms of the self-discharge in aqueous media which will play a critical role in the electrochemical performance of novel aqueous Li-ion batteries.Wissenschaftlicher ArtikelBand:373102 46 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Modeling of electrochemical oxide film growth – impact of band-to-band tunnelingThe Point Defect Model (PDM) describes the corrosion resistance properties of oxide films based on interfacial reactions and defect transport, which are affected by the electric field inside the oxide film. The PDM assumes a constant electric field strength due to band-to-band tunneling (BTBT) of electrons and the separation of electrons and holes by high electric fields. In this manuscript we present a more complex expansion of the common models to simulate steady state oxide films to test this assumption. The R-PDM was extended by including the transport of electrons and holes and BTBT. It could be shown that BTBT only occurs in very rare cases of narrow band gaps and high electric fields and the impact of electrons and holes does indeed lead to a buffering effect on the electric field, but does not lead to a constant electric field strength. Modeling the transport of electrons and holes on the oxide film allows to specifically estimate their potential impact on the film growth. Especially during modeling of oxide films with narrow band gap and/or electrochemical reactions at the film/solution interface the electrons and holes needs to be included to the model.Wissenschaftlicher Artikel160 112 - 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 72 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Prussian blue analogues as aqueous Zn-ion batteries electrodes: Current challenges and future perspectivesThe urgency of integrating renewable energy sources in the power grid has pushed the development of aqueous metal-ion batteries because of their low cost, nontoxicity, high safety, and environmentally friendliness. Among the variety of aqueous metal-ion batteries that are currently under development, aqueous Zn-ion batteries (A-ZIBs) have recently gained a great attention because of their high specific energy and high reversibility in aqueous solutions, together with the low cost and high abundancy of the zinc. In this article, the authors intend to present an overview of the Prussian blue analogue materials, which are among the most promising materials for positive electrodes in A-ZIBs because of their easier synthesis route, reversible ion-insertion, high safety, and low toxicity, highlighting their strength points and open challenges.Wissenschaftlicher ArtikelBand:2134 47 - 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:47536 85 - 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, Modeling of electrochemical oxide film growth-a PDM refinementThe Point Defect Model (PDM) is known for over 40 years and has brought deeper insight to the understanding of passivity. During the last decades it has seen several changes and refinements, and it has been widely used to analyze growth kinetics of different alloys. Nevertheless, the model has been based on still unconfirmed assumptions, as constant and potential independent electric field strength. To overcome this limitation, we introduce a Refined PDM (R-PDM) in which we replace those assumptions by using additional equations for charge distribution including new physically valid boundary conditions based on considering finite dimensions for the defects by introduction of two defect layer at the film boundaries and by calculating the potential drop at the surface of the film towards the solution over the compact double layer. The calculations by the R-PDM show that the original PDM assumptions are only valid for very specific parameter combinations of oxide film growth and vacancies transport and cannot generally be taken for granted. We believe our findings of electric field and potential drop dependency on the external potential to pave the way for a more realistic description of passive layer formation.Wissenschaftlicher Artikel174 113 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Recent advances in reactor design and control for lithium recovery by means of electrochemical ion pumpingThe necessity to tap new natural lithium sources worldwide has pushed in recent years the research in alternative methods for lithium recovery. Among them, electrochemical ion pumping is showing interesting performances, especially when addressing diluted sources. In this review, we summarize the recent advances in materials' and reactors’ design for lithium recovery by means of electrochemical ion pumping. We discuss simulations and modeling studies as a tool to study limitations and to provide improved engineering designs. In addition, we provide parameters based on lithium removal and energy consumption for a fair comparison among different ion pumping strategies. Accordingly, we stress the importance to report not only on lithium removal metrics, but also purity and energy-related parameters to provide an optimal assessment of this technology. Finally, remaining challenges and perspectives guidelines are included for future ion-pumping developments.Wissenschaftlicher ArtikelBand:3537 73 - 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 64