Hybrid electronics for smart batteries
Résumé
In order to charge / discharge batteries efficiently, it is important to know the state of the battery in detail. Based on this knowledge, battery management systems can help to control the battery cycling very precise, to accelerate cycling and to extend the life time of the battery. However, in order to gain a deeper understanding about the performance and state of a battery, conventional I-V-measurements and temperature sensing are not sufficient. In this contribution, the authors show the application of hybrid electronics in order to get additional information about the cycling behavior of the battery. The technical approach is the co-integration of additional sensor levels on the individual battery cell. Each level is featured with a series of different sensor that are partly printed and partly assembled. Therefore, a circuitry is printed on a substrate together with insulators. Ultrasound sensor, temperature sensors, and strain sensors are used in order to measure degradation events with a local resolution. Ultrasound sensor are realized by a transient measurement using US transducers and sensors. They are realized by using P(VDF-TrFE) electroactive polymers and PEDOT-PSS electrodes that can be printed using screen printing process. Alternatively, piezoceramic sensors are glued on different locations on the circuitry substrate. In order to couple the sensor signal into the battery, surrounding materials have to be selected carefully with respect to their acoustic impedance and to avoid acoustic reflections. As temperature sensor, semiconductor based digital sensor are chosen. They provide precise information about the temperature and, by the digital addressing, can be assembled in high quantity without demanding for a high number of conducting lines. In order to improve the thermal contact, thermal VIAS are realized under the temperature sensors. Strain sensors are realized by dielectric elastomer sensors. These soft sensors are assembled in a separate level on top of the first sensor scheme. By means of these sensors, the state-of-charge can be measured easily. This information are combined with models that give insight about the mechanisms within the battery. The measurement of state-of-charge by different kind of sensors disclose the early beginning of different degradation mechanisms. Based on this information, the battery can be controlled more precise by any battery management system In this contribution, we discuss layouts, assembly techniques and printing schemes in order to realize the multi-level sensor system. In this context, Hybrid electronics provides a versatile way to combine different kind of sensors with a high local resolution in order to get more accurate information about the battery and assist to reduce the cost of energy storage.
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