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Spatially resolved acoustic, mechanical and ultrasonic sensing for smart batteries

Periodic Reporting for period 1 - SPARTACUS (Spatially resolved acoustic, mechanical and ultrasonic sensing for smart batteries)

Reporting period: 2020-09-01 to 2022-02-28

SPARTACUS – paving the way to future fast battery charging
The cycling of battery cells is usually not performed on the optimum level 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 (and de-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 in order to measure 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 kind 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 is known in detail, the number of cycles can be increased, the safety enhanced by anticipating thermal runway and the qualification for 2nd life is more robust. Moreover, this kind of 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.
At the end, SPARTACUS aims for an increase in charging time by 20% without accelerating the ageing of the battery cell. The work of SPARTACUS will enhance the performance of battery cells, the safety in use, the quality management during production and the possibility to study degradation processes in the battery cell.
Within the first period of the SPARTACUS project, sensors were developed, tested and evaluated on test specimen and battery cells during cycling. Piezoceramic and piezopolymer sensors were tested under different conditions and assembled on flexible printed circuit boards to evaluate Time-of-flight signals, and attenuation in dependence on different frequencies and pre-loads. Dielectric elastomer sensors were manufactured that measure the change of geometry of the battery cell and, thus, the breathing during cycling; digital temperature sensors were evaluated and selected. For all of these sensors, electronic boards were assembled that prepare the sensor data for the CMS. Similarly, electronics for ORP-EIS were assembled. This individual work was carried out on the basis of a set of specifications drawn up at the beginning of the project.
Layouts for flexible PCBs were designed to which the sensors can be mounted with a small form factor. Wiring and connector selection were optimized. The layouts were printed and thermal VIAs were fabricated to improve the thermal contact of the temperature sensors with the battery cell.
In order to build models that correlate to the sensor data, all degradations mechanisms were listed and linked to sensor data. Aging campaigns were designed that provoke the different degradations to be investigated; post-mortem analyses were performed for validation of different degradation mechanisms. Subsequently, the aging campaigns will be repeated with the smart batteries in order to correlate the sensor data to the degradation.
CMS and BMS were designed and manufactured that are fed by the sensor data and the models developed. For reduction of wiring and the number of cables, power line communication strategies were investigated.
The performance of the smart battery, the CMS and BMS and the models used will be finally investigated by validation campaigns. Therefore, a test bench was implemented and cycling experiments in different climate conditions prepared. All safety precautions were installed in order to drive the battery beyond the specifications given by the data sheet of the supplier.
LCA analysis was started by collecting material data of the sensors.
For dissemination of the results, a web-page was set-up and s online; social media activities were carried out. The SPARTACUS project strongly supports the battery 2030+ activities in terms of road mapping, dissemination, standardizations, IP strategies, and education.
SPARTACUS project works on new knowledge beyond the state-of-the-art in different dimensions.
(1) SPARTACUS develops sensor, sensor arrays and electronics that is tailored to measure the SoC, SoH, SoP and other SoX.
(2) SPARTACUS develops models that link the set of sensor data and SoX to potential degradation mechanisms. These models will be used as base for cell management systems in order to cycle battery exactly in correspondence to the actual performance state.
(3) SPARTACUS develops the aforementioned cell management and battery management systems that benefit from the sensor data by adapting the cycling in correspondence to the new models
(4) SPARTACUS will clarify whether smart batteries are economically and environmentally beneficial compared to conventions batteries taking the costs and resources for the additional sensors into account.
(5) The data obtained with the SPARTACUS sensor technology offers a previously impossible accurate recording of the actual characteristics of batteries, selected data sets therefore also can be used to support the AI-based material development as outlined in the BATTERY 2030+ roadmap.
At the end, SPARTACUS will provide a new toolbox to battery manufacturer and battery user. Depending on usage and specification, industries can use this toolbox in order to monitor some or all values provided by SPARTACUS sensors ensuring the performance and safety of their batteries. This will pave the way to prolonged usage of batteries, a better qualification for 2nd life usage and, thereby, by a reduction of resources needed. This can be performed without reducing the performance or cycle life and independent of battery chemistry.
Sensors assembled on a battery to measure locally resolved the status of the cell
Dielectric Elastomer sensor to measure deforming of battery cells