Globally, the demand for energy has increased dramatically. At the same time fossil fuel reserves are limited and power generation from nuclear fission is controversially discussed. Therefore a radical change in the energy mix is expected in the very near future. One of the most important goals of the German government focuses on the expansion of renewable energy sources to up to 60% of the gross final energy consumption and 80% of the gross electricity consumption by 2050. In order to better regulate seasonal- and weather-dependent energy production and keep the grid frequency stable, novel flexible energy storage plants are required. One promising strategy is based on the development of peripheral electrochemical energy storage and conversion plants such as electrolysis and fuel cells for hydrogen production and combustion, double-layer supercaps, as well as redox-flow, lithium-ion, and zinc/air batteries. DFI activities focus principally on the development of active and stable catalysts as well as on intercalation materials for batteries and fuel cells.
Currently, fuel cell activities focus on the enhancement of PEMFC activity and stability and more specifically on the synthesis of mesoporous carbon with a soft-template route within the “Gra2Kat” project. The main goal of DFI research is to create a pore network with slightly larger pore size than that of catalyst particles to better immobilize them.
According to recent studies, the redox-flow battery appears to be an ideal candidate as highly scalable energy storage system for stationary applications. In the frame of the “DegraBat” project, degradation processes in All-Vanadium-Redox-Flow batteries (AVRFB) will be studied by means of accelerated aging procedures for more accurate life-time prediction. In the more prospective “Photoflow” project, influence of sunlight on redox behaviour of organic species in semiconductors will be investigated.
Because of their low vapour pressure and high electrochemical stability, some ionic liquids (ILs) are promising candidates in place of aqueous and organic electrolytes in metal/air and metal-ion battery applications, respectively. In the metal/air battery the most important challenge is to find aprotic/protic ILs that catalyse both oxygen reduction/evolution and metal dissolution/deposition. For oxygen reaction, protic electrolytes such as DEMA-TfO should be more efficient compared to aprotic ones. However, their surface tension has to be high enough for allowing 3-phase-boundary formation as well. Reversibility of Zn in IL/H2O mixtures is on investigation in the “LuZi” project. Since estimated resources related to lithium ion technology are limited (~ 50 million tonnes of lithium carbonate), development of alternative technologies such as aluminium-based ones (8% Al in earth crust) has to be intensified. DFI is involved in a European “Al-ion” and a German “AliBatt” project, both dedicated to the development of an electrically rechargeable cell with an EMICl/AlCl3-based ionic liquid electrolyte.
While contribution of renewable energy plants to electricity production continuously increases (65% by 2040), development of additional chemical storage solutions is becoming urgent to assist pumping stations, gas caverns, and electrochemical systems. Feasibility, efficiency, sustainability, and acceptance of some innovative concepts will be evaluated in the frame of the “P2X” kopernikus project. One of these concepts, in which DFI is involved, aims at transforming water and carbon dioxide into hydrogen and carbon monoxide (syngas) through high-temperature co-electrolysis in solid oxide electrolysis cell (SOEC). The impact of temperature and gas composition on the activity of nickel and alternative catalysts for the reversible water-gas-shift reaction (rWGSR) will be evaluated first in a tube reactor and finally in the SOEC. The influence of elevated pressure up to 10 bar on carbon formation will be studied in the tube reactor as well.