Poster Session October, 2016

Battery Section

Li-ion batteries (LiB). The lack of high theoretical energy density needs to be compensated by a lower price on the battery components. We previously studied the layered oxide P2- Na0.67(Mn0.5Fe0.25Co0.25)O2 where we succeeded in lowering a part of the expensive and toxic Co through the synthesis of P2-Na0.67(Mn0.6Fe0.25Co0.15)O2. The electrodes are usually prepared by mixing the active material with a carbon additive and the polyvinylidene fluoride (PVDF) in N-methyl-2- pyrrolidone (NMP). The NMP solvent is toxic, expensive and presents a boiling point at 202°C which leads to additional costs for the electrode processing. [...]

Metallic tin (Sn) is one of the most promising anode materials for next-generation lithium ion batteries (LIBs) due to its high theoretical capacity of 991 mAh g-1 or 7313 mAh cm-3, multiple times that of commercialized graphite anode materials (372 mAh g-1 or 833 mAh cm-3). However, the huge volume expansion (up to 360%) causes cracking and pulverization of the active material, consequently leading to the dramatic mechanical stress of Sn during cycling. This also leads to the loss of conductivity at the electrode, resulting in quick capacity fading, which greatly hinders the practical application of Sn as anode material and thereby letting down its application in LIBs. A composite ‘nanorattle’ type electrode with Sn metal encapsulated in a carbon shell has been synthesized which features a buffer volume to cope with the volume expansion problem.[...]
High surface area porous carbon frameworks exhibit potential advantages over crystalline graphite as an electrochemical energy storage material owing to the possibility of faster ion transport and up to double the ion capacity, assuming a surface-based mechanism of storage. When detrimental surfacerelated effects such as irreversible capacity loss due to interphase formation can be mitigated or altogether avoided, the greatest advantage can be achieved by maximizing the gravimetric and volumetric surface area and by tailoring the porosity to accommodate the relevant ion species. We investigate this concept by employing zeolite-templated carbon (ZTC) as the cathode in an aluminum battery based on a chloroaluminate ionic liquid electrolyte. [...]

Pilot production line for battery cell manufacturing
A. Fuerst, A. Haktanir, H. Roth, B. Löffel, M. Müller
The lithium-ion batteries have a wide range of applications with an increasing demand such as smart phones, laptops, electric vehicles, short term grid storage etc. Their production is based on two main stages which are electrode and cell manufacturing. Electrode manufacturing consists of three steps respectively mixing, coating and calendaring. Subsequently the cell production begins with vacuum drying in which residual water is removed from the electrodes. According to the case type different processing methods follows the drying. For instance pouch cell design continues with cutting, stacking (or Z-Folding) and assembly steps.1 At this phase there is a big improvement potential in terms of process parameters and technologies for example positioning accuracy, cutting tool, cutting speed etc. [...]

Thermal Energy Section

Closed sorption heat storage based on water vapour absorption in aqueous sodium hydroxide (NaOH-H2O) solution theoretically achieves a significantly higher volumetric energy density compared to sensible hot water storage systems. In the frame of the EU FP7 project “Combined development of compact thermal energy storage technologies - COMTES”, a prototype with 10 kW output power was designed and built. Operation was carried out in both process modes - absorption and desorption - in steady state boundary conditions. The present work focuses on the heat and mass exchanger assessment and the comparison with the results of the initial numerical model used to design the heat and mass exchanger. [...]

Water (vapour) absorption/desorption in a potentially high volumetric energy density fluid as aqueous solutions like LiCl, LiBr, KOH or NaOH as sorbent is an efficient alternative to water based sensible heat storages. Moreover, sodium hydroxide is a low cost substance with high water solubility. Nevertheless, the challenges are related to the process engineering and transferring the materials thermo-physical properties to a running system with the expected performance. [...]

Tubular SiSiC structures for high temperature solar applications
E. Rezaei, M. Barbato, S. Gianella, S. Haussener, A. Ortona

Silicon infiltrated SiC (SiSiC) is a prevalent ceramic material for applications in harsh environments such as burners, recuperators, solar receivers and heat storage systems. It has wide industrial applications due to its high mechanical and chemical stability in elevated temperatures as well as its excellent thermal shock resistance. SiSiC is also particularly suitable for near-net-shape production of complex components such as porous structures via melt infiltration of silicon. In high temperatures, above 1000°C, three main factors may limit the performance of SiSiC: bead formation due to melting of silicon, severe oxidation especially in presence of water vapor and high thermally induced stresses. The first two factors are investigated earlier for various SiSiC lattices. This work focuses on the thermal behavior of SiSiC lattices, which will be used as the base for future works on thermal stress analysis of these materials. [...]

Hydrogen Section

Efficient Electrocatalyst for Water Oxidation in Alkaline Electrolyte Derived from the Gibeon Meteorite
F. Le Formal, N. Guijarro, W. S. Bourée, A. Gopakumar, M. S. Prévot, A. Magrez, P. J. Dyson, K. Sivula

Examining the electrocatalytic performance of naturally-occurring metallic minerals is of interest for energy conversion applications given their unique atomic composition and formation history. In this study, we report the electrocatalytic function of an iron-based Gibeon meteorite for the oxygen evolution reaction (OER). This meteorite originates from sub-saharan Africa and has the largest strewnfield known with pieces discovered over 20 000 km2 in Namibia and a total collected mass exceeding 21 tons. After ageing under operational conditions in an alkaline electrolyte, an activity matching or possibly slightly superior to the best performing OER catalysts emerges, with stable overpotentials as low as 270 mV (for 10 mA cm−2) and Tafel slopes of 37 mV decade−1. The Faradaic efficiency for the OER was unity and no deterioration in performance was detected during 1000 hours of OER operation at 500 mA cm−2. Mechanistic studies suggest an operando surface modification involving the formation of a 3D oxy(hydroxide) layer with a metal atom composition of Co0.11Fe0.33Ni0.55, as indicated by Raman and XPS studies and trace Ir as indicated via elemental analysis. The growth of the catalyst layer was self-limiting to be lower than 200 nm after ca. 300 hours of operation as indicated through XPS depth profiling and cyclic voltammetry. The unique composition and structure of the Gibeon meteorite suggest that further investigation of Ir–Co–Ni–Fe systems or other alloys inspired by natural materials for water oxidation are of interest. [...]

Technology Interaction Section

An increasing contribution of renewable energy technologies to global energy supply is needed for climate change mitigation. However, some key technologies such as solar and wind energy do not offer the same level of dispatchability as fossil generators do. Energy storage is a solution to increase the penetration and value of renewable energy technologies and there are different technologies available in the market depending on the application scale and discharge duration. [...]