| Work Detail |
Researchers have created a degradation model that experts can use to determine battery aging in hybrid systems consisting of lithium-ion batteries and supercapacitors. This makes it possible to determine whether it makes sense to combine both technologies in specific cases. The tools should also help in the design of a hybrid system.
Supercapacitors, also known as supercaps, can absorb and provide a lot of energy in a very short time without affecting their lifespan. However, their energy density is low, so their capacity is quickly depleted. Lithium-ion batteries, on the other hand, have a large capacity, but do not cope well with short-term load peaks. This is because they suffer from thermal stress, which causes them to age more quickly.
In many applications – for example in electric transport and construction machinery – it can therefore make sense to combine both storage technologies: batteries for continuous operation and supercapacitors for peak loads such as recuperation, i.e. the recovery of braking energy. However, it has so far been difficult to reliably predict how coupling with a supercapacitor will affect the battery life. This makes the decision on such a system and also its design difficult.
Within the framework of the research project "SukoBa", the Fraunhofer Institute for Energy Economics and Energy Systems Technology (IEE) has developed simulation tools for such hybrid systems together with its partners Skeleton Technologies and AVL. The core of these tools is a degradation model for predicting battery ageing, which is based on the BaSiS simulation environment developed by the Fraunhofer IEE. With its help, the service life of batteries in hybrid storage systems can be increased by up to 20 percent, the research project shows.
"Our toolbox provides meaningful data that potential users can use to make a confident decision for or against combining the two technologies," says project leader Wei Wei Shan of the Fraunhofer IEE.
Accurate battery aging predictions
The degradation model developed in the project allows analyzing different configurations and control algorithms to find the best combination of supercapacitors and batteries in terms of lifetime and cost for a specific system design and different operating scenarios.
To achieve this, the model simulates, among other things, the behaviour of the battery in a hybrid system under realistic operating conditions. From there, the software obtains an exact prediction of battery ageing, which is essential for extending battery life through precise hybrid system design and customised control strategies. The tool can also be used to determine whether and to what extent the battery size can be reduced in such a system in order to save costs.
According to Fraunhofer IEE, the toolbox is designed to be so flexible that new trends in batteries, supercapacitors and power electronics can be taken into account.
Expert webinar on hybrid storage systems
The degradation model is based on the Fraunhofer IEE software BaSiS (Battery Simulation Studio), a simulation environment for dynamic processes and aging effects of electrochemical energy storage devices. BaSiS is used in the development, testing and optimization of cells, batteries, packs, components and management systems in the mobile and stationary sectors.
The BaSiS model must be parameterized based on the battery technology used in order to provide reliable predictions. Fraunhofer researchers obtain the battery model parameters from design data and experimental measurements of battery cells, independent of the battery manufacturer. |
