Rechargeable Oxide Batteries: Kinetic Study of Iron-Based Storage Materials in Low pO2-(H2O-Vapour)-Atmosphere
Public discussion often reduces the term “Energiewende” to the sector electricity which covers about 31 % of the actual energy production in Germany . However, Germany’s goal is to balance at least 60 % of gross end energy consumption through renewable energy by 2050 .
For this purpose, we are faced to the fact to develop appropriate energy storage technologies, in order to obtain a decentralized and centralized power supply, allowing us to stabilize and compensate for the volatile availability of regenerative power plants.
As a novel concept high-temperature-metal-metaloxide storage systems (known as Rechargeable Oxide Battery (ROB)) were developed and examined (figure 1). The specific storage density is comparable to that of Li- or Na-S batteries and significantly higher than that of common lithium-ion batteries.
ROB storage materials imply a high volumetric energy density (= 3,04 Wh/) and therefore, offer great potential for application in the field of energy storage . For this reason, the present work gives a fresh view on kinetic studies that illuminate particular redox-properties of selected Fe-based alloys (e. g. Fe-Y2O3, Fe-Al2O3, Fe-CaO) with respect to the H2-formation/consumption. These specific properties were detected by mass spectrometry (MS). The MS-measurements are accompanied by thermogravimetric (TG) and differential thermal analytic (DTA) methods; the aim being to acquire a better understanding of typical Fe-reaction (to wustite, hematite, and iodestone) in a simulated low pO2- atmosphere (Ar/4%H2/7%H2O) combined with a high temperature environment of 600-1000 °C. The composition and morphologies of the oxide scales were analyzed by optical metallography (OM), scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD).
In particular, the redox cyclability of the selected storage media plays an essential role in the charge and discharge behavior of a ROB. In this context, our studies present results of cycling experiments (n = 5-10) which show redox-responding behavior of the investigated materials and provide evidence towards the long term stability.
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