Research

Lithium-ion batteries

The lithium-ion battery is currently the most important type of battery among the rechargeable high-performance batteries. While small lithium-ion batteries are already being used commercially in consumer electronics, electrical tools, hybrid vehicles, and electric cars, the commercial use of larger energy storage units is still in its early stages. The maximum storage capacity of conventional lithium-ion batteries has, however, nearly been reached. In order to achieve advances in performance, it is therefore necessary to press ahead with the development of new storage material and approaches. New electrochemical pairings and new ideas for an even more compact design are needed to achieve another significant jump in energy density.

Representative Research Field Li-Batteries

Post-lithium batteries

Lithium-ion and metal hydride batteries are established systems that are currently being successfully employed for energy storage in electrically powered applications. In order to make future devices safer, less expensive, more sustainable, and more powerful, global research is looking for alternatives to the current systems. Lithium is supposed to be replaced by other elements which can also make bidirectional batteries possible. In order to attain this goal it is necessary for us to develop anew all the components of the battery and to acquire an understanding of the electrochemical processes. Of the four new types of batteries that are currently the object of international research, which are based on using magnesium, sodium, chloride, or fluoride as the charge carriers, two (the chloride-ion and fluoride-ion batteries) were first presented by HIU. HIU developed the electrolyte that is currently the best for use in a magnesium battery; this has also made it possible to build the first reversibly working magnesium-sulfur cells with extended cycles. With the exception of the sodium-ion battery, all of these systems have the potential of achieving markedly higher energy storage densities than the present lithium-ion batteries. HIU has played a pioneering role in these new fields of research.

Representative Research Field Post-Li-Batteries

Alternative electrochemical storage and conversion devices

Fuel cells are among the enabling technologies toward a safe, reliable, and sustainable energy solution. Yet the lack of clean hydrogen sources and a sizable hydrogen infrastructure limits the fuel-cell applications today. Due to their elevated operating temperature, between 150°C and 180°C, high-temperature proton exchange membrane fuel cells (HT-PEMFCs) based on phosphoric acid doped polybenzimidazole (H3PO4/PBI) membranes can tolerate fuel contaminants such as carbon monoxide (CO) and hydrogen sulfide (H2S) without considerable performance loss. These are typical byproducts of the steam reforming process, which produces hydrogen from hydrocarbon fuels such as methanol or natural gas. So it is an appealing concept to couple a HT-PEMFC stack directly with a fuel processor, which can be used as auxiliary power units (APUs). These APUs use the fossil fuel resources more efficiently and help reduce emission of CO2. This might also be a good strategy for the wide deployment of fuel cells before the hydrogen infrastructure is established. The fuel cell system’s efficiency can be further increased by reusing the exhaust heat produced during electrical power generation.
The slow oxygen reduction reaction in concentrated phosphoric acid remains a major technological challenge for future development of HT-PEMFCs. The slow reaction rate is believed to be related to strong adsorption of phosphoric acid species on the surface of the platinum catalyst. It is generally accepted that adsorption of molecular or anionic species from the concentrated phosphoric acid electrolyte hinders ORR by blocking active sites on the catalyst surface. To gain a better understanding of the adsorption mechanisms we conduct systematic studies employing various types of perfluoroalkylated derivatives of phosphoric acid. We evaluated these model electrolytes for their adsorption behavior and influence on ORR on a polycrystalline platinum surface.

Representative Research Field Alternative Storage