Safe and economic use of batteries is strongly dependent on a solid understanding of the performance of the batteries under various operational modes and environments. SINTEF is performing scientifically based evaluations of the electric and thermal performance of batteries under different temperatures and load cycles by using standard tests (charge/discharge, load cycling) and more sophisticated techniques such as AC impedance spectroscopy.
The evaluation of battery lifetime is also performed by a combination of experimental methods and mathematical modelling. Experiments are performed in order to obtain input to standard degradation models and to validate custom made aging models for specific batteries and battery chemistries.
In the application below, a simple general lifetime prediction model is presented where the remaining capacity of a commercial Li-ion battery as a function of time is estimated.
The model uses inputs such as the average state of charge of the battery, temperature and number of daily 100% charge discharge cycles to estimate the remaining available capacity (normalised against the nominal capacity) over a period of 1000 days. The model is based on parameters extracted from standard measurements performed on a commercially available Li-ion battery
More advanced models than the model presented above which also can evaluate various load profiles as well the impact of the thermal characteristics of battery cells are also available or can be developed from existing methodology and experimental data.