Poster Session October,2015

Battery Section

Li-ion batteries are starting to reach their limits in terms of energy density, cost and abundance, and progress is slower than expected. Thus, researchers are currently re-investigating other alkali metals as Li substitutes, mainly focusing on Na. This system has been considered to be purely academic, and no real applications or prototypes have been developed to investigate its viability or possible commercialization, the only exception being the high temperature Na-S system, which was commercialized in the 1960s. Recently however, the amount of research and number of papers de-voted to the development of active materials for Na-ion batteries has increased exponentially, leading the community to consider the commercialization of Na-ion batteries in the near future. To achieve commercialization, suitable anodes and cathodes must be developed and studied in depth as the Na-system is often not analogous to the Li-system. Recently, we have developed a new type of anode material, MSnS2 (M = Fe, Cu), that is able to cycle in both lithium-ion and lithium- sulphur batteries. By tuning the potential window, we attained specific charges greater than 750 mAh/g and 500 mAh/g for the Li–S and Li–ion system, respectively, after 400 cycles [1]. [...]

Influence of stress cycling on Li-Ion batteries for light vehicle applications


E. Stilp, E. Cuervo Reyes, D. Adams, M. Held, and U. Sennhauser

In order to provide energy for light vehicles Li-Ion batteries are used due to their high power and energy density. In order to optimize battery life time and for developing battery management systems knowledge about the aging behavior is essential. In this study we investigated the influence of different types of stress cycles on the charge capacity fading (see Fig. 1, left) of A123 AHR32113M1 Ultra-B battery cells, consisting of a LiFePO4 cathode and a graphite anode.1 Electrochemical impedance spectroscopy (EIS) was utilized to connect the charge capacity losses with degradation processes.2 To get a microscopic inside of a stressed battery ps-laser cuts polished by FIB have been performed and the cross section was imaged using SEM (Fig. 1, right). [...]

Battery Testing @ EMPA


M. Held, D. Adams, D. Bachmann, E. Cuervo Reyes, E. Stilp, U. Sennhauser

Rechargeable Lithium-ion batteries are ubiquitous in consumer electronics such as cell phones, laptops and tablet computers. Due to their high energy density they were introduced in automotive and aerospace applications and emerge now also into large energy storing facilities. Depending on the materials for the anode, cathode, and electrolyte the voltage, capacity, lifetime, and safety of Lithiumion batteries can change dramatically. The Reliability Science and Technology Laboratory performs cell and battery characterization, degradation and lifetime testing as well as modelling and materials analysis. Automated test stations provide a unique capability for characterization and testing of cells, cell packs and large batteries.
An increasing concern in developing highly efficient electricity storage devices leads carbon nanotube (CNT) based supercapacitors towards the front-edge of current research.[1] To further improve energy storage density, pseudocapacitive manganese oxide (MnO2) has been frequently decorated on CNT matrix. 2-5 A systematic study to optimize the mass ratio between these two materials, however, is missing. We hereby show that the optimal gravimetric specific capacitance (Cm) of 150 F/g can be achieved at 335 μg/cm2 MnO2 mass loading. It is also demonstrated in this work that electrode prepared by our facile pulsed current electrodeposition method (PCE) presents an enhancement of ~50% in Cm over conventional direct current method (DCE). Moreover, such a method is versatile that may also be extended to other pseudocapacitive oxide coatings. [...]

Currently the electricity production still relies strongly on the conversion of heat via the mechanical work of a turbine, but this approach cannot be used efficiently at temperatures up to 200 °C. Here, I propose a new approach based on thermo-electrochemical systems to convert low-grade heat first into a chemical energy that can then in turn be converted on demand into electricity through an electrochemical reaction. To illustrate this principle, a copper battery based on complexation with acetonitrile was chosen as a model system, as this system is especially effective for using low quality heat of less than 150 °C to produce and store electricity.1 [...]

Thermal Energy Section

Analysis of industrial-scale high-temperature combined sensible/latent thermal energy storage


L. Geissbühler, M. Kolman, G. Zanganeh, A. Haselbacher, A. Steinfeld

A thermocline thermal energy storage (TES) based on a packed bed of rocks as sensible heat storage material and air as heat transfer fluid is well suited for advanced adiabatic compressed air energy storage (AA-CAES) plants. In prior work, this type of TES was shown to give 95% overall (charging-discharging) thermal efficiency at charging temperatures of up to about 600 °C. One drawback of sensible heat thermocline TES is that it suffers from decreases in the outlet temperature during discharging, thus reducing the efficiency of the AA-CAES plant. The temperature decrease can be avoided by oversizing the storage, but this increases material costs and is therefore undesirable. An alternative method of avoiding temperature decreases during discharging is through the use of encapsulated phase-change materials (PCM). [...]

The development of technologies for energy storage has been intensified in recent years driven by the disparity between energy availability and demand. Latent heat storage by means of phase change materials (PCM) is an attractive heat storage technology. Key advantages include the high energy storage density, applicability to high temperatures, and the ability to store and release heat at a constant temperature. The implementation of an efficient high temperature heat storage system requires in depth understanding and characterization of the phase change processes for subsequent computational modeling, performance estimation, and design optimization. [...]

Open-celled cellular ceramics are attractive structures for high temperature applications such as heat exchangers, recuperators and solar receivers. Si-infiltrated SiC is considered as a desirable material for these structures due to its enhanced thermal and mechanical properties at high temperatures. Because of the demanding conditions, these structures are often subjected to thermally induced stresses. These can induce local crack formations followed by local failure of the structure. Besides, in presence of air, both Si and SiC oxidize in either passive or active mode. Passive oxidation results in formation of a protective SiO2 layer while active oxidation forms volatile SiO causing material gradual weight loss. In this study, ad-hoc experiments have been designed to observe the behavior of five porous structures in two different oxidative environments at temperatures up to 1400°C. A group of samples have been thermally shocked in a porous burner while the other group was oxidized in the steady state condition of an electric air oven. Samples’ microstructure and mechanical behavior was then characterized. [...]

Hydrogen Section

Scale-up of the All-Vanadium Dual Circuit Redox Flow Battery for SImultaneous Desulfurization and Renewable Hydrogen Generation


P. Peljo, H. Vrubel, V. Amstutz, C. R. Dennison, A. Santasalo-Aarnio, D.Lloyd, F. Gumy,a K. E. Toghill, H. H. Girault

Increasing use of renewable intermitted energy sources like wind and solar energy require growing amounts of energy storage capacity and power.[1] This energy storage should be flexible, cheap, and utilizable on a GWh scale. Redox flow batteries have been identified as a promising candidate for this task. A redox flow battery (RFB) is a type of secondary battery system in which charge is stored and released by oxidizing or reducing active species dissolved in an electrolyte solution.[1] The advantage of these systems is that the power and energy storage capacity are decoupled, making RFBs well suited for applications requiring specific power and/or energy storage capacity. However, these systems suffer from low energy storage density, limited by the solubility of the active species in the electrolytes.[1] For this purpose, we have recently developed a concept of dual-circuit redox flow battery.[2] The battery based on Ce-V functions as a conventional RFB, but when the energy storage capacity oft he battery is full, secondary circuits are used to chemically discharge the battery to produce hydrogen, in effect doing indirect hydrogen evolution. As the RFB utilizing the V/Ce redox chemistry suffers from some significant problems,[2] in this paper we focus on the concept and scale-up of a dual circuit vanadium redox flow battery. Additionally, the system can be utilized to convert hazardous pollutants like sulphur dioxide and H2S to more environmentally benign substances like sulphur and sulphuric acid.[3] We also present the results from the scale-up of the dual circuit allvanadium RFB able to produce hydrogen by the rate of 1 kg/day.[3] [...]

Fast e-Fueling Stations
H. Vrubel, V. Amstutz, P. Peljo, F. Gumy, C. R. Dennison, A. Battistel, T. Wu, H. Girault

In order to ensure greater energy sustainability and reduce greenhouse gas emissions, there is a growing shift toward alternative fueled vehicles, such as battery- and fuel cell electric vehicles. However, the current lack of hydrogen infrastructure is a well-known barrier to the implementation of fuel cell vehicles. Additionally, the electric vehicles become increasingly common, load is shifted from the existing petroleum infrastructure to the electrical grid. The resulting unpredictable, large amplitude fluctuations that arise due to fast charging can significantly affect power quality and grid stability. In order to fully realize the shift to sustainable, alternative-fueled vehicles, an appropriate fueling infrastructure must be developed.[...]
The Platinum, bloc d, noble metal, has really interesting catalytic properties for different chemical reactions, specially the oxygen reduction reaction, essential in fuel cells. A large scale production of fuel cells using platinum metal as catalyst is too expensive. The synthesis of bimetallic nanoparticles coated on carbon permit to obtain high performances and really cheaper catalyst for the oxygen reduction. The synthesis method developed by H. Zhang and all1 based on galvanic replacement (Fig 1) is really interesting to produce core-shell palladium-platinum nanoparticles with well defined structure and good catalytic activity. [...]

Technology Interaction Section

The temporal variability of renewable energy technologies ranges from seconds to seasons and therefore the continuous balance of supply and demand calls for energy storage solutions. Amongst them, power-to-gas (P2G) is a modular energy storage technology which could offer several benefits to different types of networks (e.g., electricity and natural gas) and sectors (e.g., residential and transport) while playing the role of mid-term and long-term energy storage. The core element of a P2G plant is the electrolyser system which transforms low cost and/or renewable electricity into hydrogen. A thorough analysis of the implications of selecting a specific electrolyser technology (namely alkaline or PEM) and scale is key for understanding the performance and economic benefits of P2G plants generating hydrogen or methane. [...]