Segmented printed circuit board electrode for locally-resolved current density measurements in all-vanadium redox flow batteries

One of the most important parameters for the design of redox flow batteries is a uniform distribution of the electrolyte solution over the complete electrode area. The performance of redox flow batteries is usually investigated by general measurements of the cell in systematic experimental studies such as galvanostatic charge-discharge cycling. Local inhomogeneity within the electrode cannot be locally-resolved. In this study a printed circuit board (PCB) with a segmented current collector was integrated into a 40 cm2 all-vanadium redox flow battery to analyze the locally-resolved current density distribution of the graphite felt electrode. Current density distribution during charging and discharging of the redox flow battery indicated different limiting influences. The local current density in redox flow batteries mainly depends on the transport of the electrolyte solution. Due to this correlation, the electrolyte flow in the porous electrode can be visualized. A PCB electrode can easily be integrated into the flow battery and can be scaled to nearly any size of the electrode area. The carbon coating of the PCB enables direct contact to the corrosive electrolyte, whereby the sensitivity of the measurement method is increased compared to state-of-the-art methods

Energy consumption of current and future production of lithium-ion and post lithium-ion battery cells

Due to the rapidly increasing demand for electric vehicles, the need for battery cells is also increasing considerably. However, the production of battery cells requires enormous amounts of energy, which is expensive and produces greenhouse gas emissions. Here, by combining data from literature and from own research, we analyse how much energy lithium-ion battery (LIB) and post lithium-ion battery (PLIB) cell production requires on cell and macro-economic levels, currently and in the future (until 2040). On the cell level, we find that PLIB cells require less energy than LIB cells per produced cell energy. On the macro-economic level, we find that the energy consumption for the global production of LIB and PLIB cells will be 130,000 GWh if no measures are taken. Yet, it is possible to optimize future production and save up to 66% of this energy demand

Alliances and the innovation performance of corporate and public research spin-off firms

We explore the innovation performance benefits of alliances for spin-off firms, in particular spin-offs either from other firms or from public research organizations. During the early years of the emerging combinatorial chemistry industry, the industry on which our empirical analysis focuses, spin-offs engaged in alliances with large and established partners, partners of similar type and size, and with public research organizations, often for different reasons. We seek to understand to what extent alliances of spin-offs with other firms (either large- or small- and medium-sized firms) affected their innovation performance and also how this performance may have been affected by their corporate or public research background. We find evidence that in general alliances of spin-offs with other firms, in particular alliances with large firms, increased their innovation performance. Corporate spin-offs that formed alliances with other firms outperformed public research spin-offs with such alliances. This suggests that, in terms of their innovation performance, corporate spin-offs that engaged in alliances with other firms seemed to have benefitted from their prior corporate background. Interestingly, it turns out that the negative impact of alliances on the innovation performance of public research spin-offs was largely affected by their alliances with small- and medium-sized firms

Stand und Perspektiven von Redox-Flow-Batterien als stationäre Speicherlösungen

Germany is emphatically pursuing the extension of renewable energy. For a safe and efficient energy supply the provision of energy, especially against the background of fluctuating input as well as the local and temporal use of energy has to be balanced. This is mainly done today by the power grids, yet these don’t have storage capacities to stabilize fluctuations. Electrochemical storage devices or batteries are among the established technologies for storage of electric energy and are versatilely used, such as for uninterruptible power sources. Storing electric energy with help of electrochemical storage devices in a higher Kilowatt (KWh) to Megawatt (MWh) scale cannot be installed economically today. This also has to do with the fact that the high storage costs increase almost proportionally to the installed capacity. This basic problem could be partly solved by the use of Redox-Flow-Batteries (RFB). In the following RFB are discussed according to their electrochemical properties and development potentials in order to give an assessment of potentials to reduce costs

Methode zur Speicherung von elektrischer Energie in ionischen Fluessigkeiten

WO 2010094657 A1 UPAB: 20100908 NOVELTY - The redox-flow-battery comprises a water-free electrolyte having ionic fluid, positive and negative half cells (f) having ionic fluid, where the ionic fluids are same or different, and vanadium ions (V4+/V5+) as redox-pair for the positive half cell and V4+/V3+ as the redox pair for the negative half cell. The electrolyte comprises 0.1 wt.% of the ionic liquid(s). The operating temperature of the redox-flow-battery is -30 degrees C to 400 degrees C. The concentration of the vanadium ion in the electrolyte is 0.1-10 mol/l. DETAILED DESCRIPTION - The redox-flow-battery comprises a water-free electrolyte having ionic fluid, positive and negative half cells (f) having ionic fluid, where the ionic fluids are same or different, and vanadium ions (V4+/V5+) as redox-pair for the positive half cell and V4+/V3+ as the redox pair for the negative half cell. The electrolyte comprises 0.1 wt.% of the ionic liquid(s). The operating temperature of the redox-flow-battery is -30 degrees C to 400 degrees C. The concentration of the vanadium ion in the electrolyte is 0.1-10 mol/l. The redox pair is formed from the ionic liquid in both half cells of the redox-flow-battery. The electrolyte does not include the additive of stabilizing agent, acids and/or bases. The electrode (b) of the battery is metallic electrode, diamond electrode or indium-tin-oxide electrode. USE - Used as redox-flow-battery. ADVANTAGE - The redox-flow-battery has improved variability in selection of operating parameters such as temperature or selection of electrode material

Investigations of the anodic oxidation of ethanol under forced convection and ambient conditions

The electro-oxidation of ethanol was investigated in alkaline solution (0.5 M ethanol and 0.1 M NaOH) on a polycrystalline platinum electrode. The electrode was positioned in a flow channel (channel electrode) which ensures controllable and defined convection conditions in the electrode surrounding. Moreover, a flow through UV-Vis absorbance cell was used for intermediate (acetaldehyde) detection and its quantification. It was experimentally observed that the intermediate current efficiency is a function of flow rate. Furthermore, the intermediate current efficiency increases with increasing surface poisoning during ethanol oxidation. From the experimental results it can be estimated that the intrinsic current efficiency for the pathway to acetaldehyde is at least 73(3)%. Hence, the current efficiency for pathways leading directly via surface reactions to other reaction products is at most 27(3)% (both are integral values over 15 min of oxidation at 0.6 V vs. RHE)

Development Study of an Air Independent Fuel Cell System for an Autonomous Underwater Vehicle

The paper is focused on the design concept of a fuel cell system for an autonomous underwater vehicle (AUV) developed within a common project of the German Navy research institute WTD 71, Fraunhofer ICT and the norwegian defense research institute “Forsvarets forskningsinstitutt (FFI)”. The presented work is therefore based on the boundary conditions for the system defined in this project. However, a more general approach is pursued by not only presenting the developed fuel cell system, but by defining a design strategy and applying it to the framework of the development in the project. For this, constraints and objectives which define the development will be defined as boundary conditions. Most of these boundary conditions also apply to the general development of air independent underwater systems and can therefore be used to outline similar systems. Based on the literature and the constraints, system and subsystem solutions for fuel cell systems are discussed to find the most suiting system for the AUV. The different system solutions are discussed on the basis of different objectives for the system design, namely space, runtime, stability and efficiency