Methods and Competencies
The focus of our research and development activities is on the optimum integration of energy storage systems into applications of different kind. Depending on the applications optimum integration could mean to minimise life cycle costs, weight, volume or environmental impact, or to maximise lifetime, efficiency and safety. In any case a reliable power supply when ever it is needed is the primary goal.
We are investigating and developing procedures, algorithms and tools for an analysis of the above mentioned issues based on a detailed understanding of the processes and reactions inside the cells. They can be used either for digital design process based on simulation models to identify the best suited storage systems design or most efficient energy management strategies. Other algorithms are used for online diagnostics. The focus is on batteries of any kind and supercaps, but methods and competences can be used as well for other storage technologies and fuel cells.
- Electrical and thermal simulation models allow to analyse the performance already during the digital planning process or to identify optimised management and operation strategies.
- For battery diagnostics in applications we are developing efficient algorithms for the prediction of state of charge, state of health, power capability and other states of function which are needed for a reliable battery and energy management.
- Impedance spectroscopy is a key tool for modelling and diagnostic. We are using it in the laboratory as well as in stationary and mobile applications for diagnostic purposes. The application of our impedance-based modelling approach has been demonstrated also for organic LEDs (OLED).
- As part of an institute for power electronics we are also developing specialised power electronics and measurement equipment for batteries. This includes the development of a multi-channel impedance spectroscope especially for batteries and fuel cells, and a battery simulator which can be used inside a car instead of the battery and which acts with virtually any battery characteristic.
- For fuel cells we are developing specialised hardware for the measurement of current densities, cell and half cell potentials, temperatures and impedance spectrums with high spatial resolution in laboratory cells. This supports basic research on efficiency, ageing processes and design of fuel cells.
- With our professional battery test laboratory we are characterising batteries with regard to capacity, power capability, temperature dependence, efficiency or lifetime. This includes very complex test procedures which may represent real life conditions and may include several thousand steps.
- By combing different test procedures in the lab, electrochemical analysis and detailed modelling we are analysing ageing processes of batteries. Based on these findings we can estimate the lifetimes in different applications and with different operating profiles.
- Especially for lead-acid batteries lifetimes, reversible capacity loss and charge acceptance in part state-of-charge cycling depend significantly on charging strategies and cycling history. Therefore we are analysing systematically charging strategies and charge acceptance of lead-acid batteries aiming at optimised operating procedure in field operations. This is of special importance in all application where charging time is limited.
- In our lab we can prepare pilot cell in button cell format for the characterisation of electrode materials for lithium-ion batteries. This allows characterising new materials by electrical test and impedance spectroscopy.