Battery research at Fraunhofer

Fraunhofer is active in every field of research surrounding battery technology

The researchers of the Fraunhofer-Gesellschaft are experts in every field, from the development of innovative materials and the optimal construction of battery cells, through efficient production methods, to sustainable energy storage. The Fraunhofer Battery Alliance involves 19 institutes. Their goal is to ensure the ongoing development of existing materials and technologies and to provide industry with innovative, practical solutions.

However, it’s not about spectacular new inventions or scientific break-throughs. This is not expected, given the current state of the science. World-wide, experts expect that in the next five years, it will be possible to make incremental improvements in the existing materials, construction and production of rechargeable batteries. No one is expecting to make a spectacular break-through and develop a “super battery”.

Efficient materials, short charging times

The most urgent priority is the incremental improvement and optimization of battery technology. To achieve this, researchers are experimenting with new materials and new combinations of existing materials, for example, sodium-sulfur or lithium-sulfur batteries. These raw materials are readily available and inexpensive. These issues are being looked into primarily by the Fraunhofer Institute for Material and Beam Technology IWS in Dresden, the Fraunhofer Institute for Chemical Technology ICT in Pfinztal and the Fraunhofer Institute for Silicon Technology ISIT in Itzehoe.

Experts have high hopes for metal-air batteries. Typical batteries produce electricity based on the electrochemical reaction of two different materials, such as nickel oxide hydroxide and cadmium. In metal-air models, only metals such as lithium or zinc are needed. The reactant oxygen is derived from the surrounding air using an electrode. This leads to increases in storage density. In particular, lithium-air batteries are showing great potential. The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Bremen is working in this area.

In everyday life, the charging time for batteries remains a problem. Petrol-powered cars can be refueled within minutes, whereas the current state of technology means that a battery-powered car can take hours to recharge.

Cell production

Manufacturing processes are also a priority. Here, the focus is on efficient, ecological, inexpensive battery production. The Fraunhofer Institute for Silicon Technology ISIT, for Ceramic Technologies and Systems IKTS, for Material and Beam Technology IWS as well as for Manufacturing Engineering and Automation IPA are all committed to this field. The IPA is working on the issue of reducing production costs. In the “LoCoTroP” project, together with its partners, the Institute is working on a dry-coating process for battery electrodes. This makes energy efficient production possible at significantly reduced costs, compared to solvent-based processes.
The IKTS is making use of its expertise in ceramics to optimize the preparation of active materials and separator components and to pursue the continued processing of the materials into battery electrodes. The ISIT is conducting research into flexible production processes which, among other things, allow lithium cells to be tailor-made for a variety of uses. The institute possesses an “electrochemical system construction kit”; these components can be assembled as needed. As part of its “DryLIZ” research project sponsored by the BMBF (Bundesministerium für Bildung und Forschung: Federal Ministry of Education and Research), the IWS was able to significantly reduce both the processing time for electrode assembly and the processing costs.

Safety tests for new battery types

Safety is a central issue. Highly compressed, complex batteries can react in treacherous ways under certain circumstances. A small defect can go unnoticed for a long time, but can suddenly result in fire. This means that comprehensive safety tests are a mandatory part of the program. The Fraunhofer Institute for Chemical Technology ICT, the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut EMI, and the Fraunhofer Institute for Solar Energy Systems ISE are all working on battery safety. Most importantly of all, in order to eliminate every risk ahead of time, new battery types and concepts must be tested before they can be brought to market.
Crash tests show how batteries, such as the battery of an electric car, react in extreme situations. Batteries are hit, buckled, pulled, hit with pointed, sharp and blunt instruments and subjected to extreme temperatures. Thus researchers can analyze what effects the damage has on the battery and whether safety is negatively impacted as a result. This means that the construction quality of the batteries can be improved. The combination of materials used is also subject to safety tests, as in isolated cases it is possible for poisonous gases to be emitted.
Battery management is an undervalued subject. The aim is to develop a system able to provide exact information about battery charge levels at any time, and able to predict how much longer the battery will last.

Batteries for stationary power supplies

Energy storage is not only important for electric cars. In the future, stationary facilities such as emergency power generators in hospitals or in private homes will run on batteries. For example, researchers at the Fraunhofer ICT are developing redox-flow batteries. With these batteries, energy is stored in liquid form in external tanks. The power converters and the electronics are separated from one another. This allows for the battery performance needed to be scaled at any time to nearly any level. While batteries for mobile devices or cars are highly dependent on weight and size, these factors are not nearly as important for stationary storage.
The European Union, along with the German government and individual regional governments within Germany, are sponsoring the research initiatives of the Fraunhofer-Gesellschaft.
In 2011, the corner stone of the Fraunhofer Institute for Silicate Research ISC was laid in Würzburg for a Fraunhofer Research and Development Center for Electromobility Bavaria, sponsored by the Bavarian Ministry of the Economy. Additionally, the Bavarian Network for Electromobility is being expanded, to pursue additional aspects of electromobility in an integrated way.
The perfect universal battery that gives everyone exactly what they want - high-performing, small, light, safe, environmentally friendly and inexpensive - is definitely not just around the corner. But, batteries optimized for their intended application, suitable for everyday use and economically viable, are in sight.