SPARTACUS – paving the way to future fast battery charging
The charging of battery cells is usually not performed on the maximum speed since the battery
management systems has to ensure that the cycle-life is not affected and that any defect generation
and thermal runways are avoided. In order to increase the speed of charging more
information is needed in order to get a full picture about the state of health (SoH) of the battery.
The SPARTACUS project turns a commercial battery cell into a smart battery that is equipped with
sensors in order to measure changes in the Young’s Modulus, the geometry, the temperature and the
electrochemical reactions that are linked to the state of the battery. All of these measurements are
related to special degradation effects, such as e.g. lithium plating, electrolyte decomposition etc.. Since
these kinds of defects do not necessarily take place homogeneous over the battery cell, sensor arrays
are realized that measure the aforementioned values with a spatial resolution.
When more information is available and the SoH can be estimated much better and the batteries cycle life can be increased, the safety enhanced by anticipating a thermal runway and the qualification for 2nd life is
more robust. Moreover, the SPARTACUS sensor set-up as developed in SPARTACUS can assist to qualify
the battery cells during/after production and supports the scientific community to study in detail
degradation mechanisms in battery cells by providing additional physical cell parameters.
SPARTACUS project demonstrated 5 types of non-invasive sensors to determine the battery state, such as SoC, SoH or SoS: Ultrasonic sensors,dDielectric elastomer sensors to measure deforming of the battery, temperature sensor array and Odd-random-phase-Enhanced Impedance spectroscopy (ORP-EIS). The data from all different sensors could be used to improve SoC estimation detecting different electrochemical stages during cycling. For ORP-EIS, the SoH could be detected whereas temperature and dielectric sensors could be used for early detection of thermal runway (SoS). A Cell management systems and pre-processing electronic was developed that can take benefits of the sensor information and forward it to the battery management system. Models were implemented in the battery management system. For validation, abusive tests and tests comparing virgin and aged batteries were carried out to show the effects on the sensor signals. From an economic and ecologic perspective, the application of sensors is still not beneficial, mostly due to the electronics that has to be used additionally. Main conclusion is that the use of sensor arrays on cell level provides benefits only, when costs of sensors can be reduced by a lean sensor architecture.
SPARTACUS discussed the results within Battery 2030+ CSA, on conferences and on industrial workshops. The developments found an excellent base for smart batteries with higher TRL and for follow-up projects, such as e.g. in combination with self-healing battery materials. One patent was filed referring to dielectric elastomer sensors for battery application.
