Structural Energy Storage for Space Application

Kurzfassung

With increasing electrification and the desire for longer energy supply, the research about efficient energy storage attracts huge scientific attention. When it comes to raising cycle life, allowing high power delivery and reducing system weight, the hybrid use of batteries and capacitors might be a ground-breaking solution. This research article deals with structural integrated supercapacitors for space application. The aim is to create a load carrying structure with the additional functionality of storing electric energy. Furthermore the device should be mechanically robust and more lightweight and volume saving compared to a state of the art construction. The electrical potential of structural supercapacitors is shown by building a demonstrator, for an energy recovery system of a high torque wheel (HTW). Laboratory test are performed, showing the electrical functionality of the integrated supercapacitors. The electronics for energy conversion between HTW and supercapacitors is mounted on top of the energy storing structure, to demonstrate the mechanical load carrying ability, especially during mechanical tests. The system is manufactured of glass fibre reinforced polymer (GFRP), equipped with 14 supercapacitors as interlayers. Compared to an equal load carrying system with commercial supercapacitors, a weight reduction of 72% and a volume reduction of 79% can be reached. Taking all system weight into account, the gravimetric specific capacity of one supercapacitor was 1.43F/g. The curing of the GFRP and the integrated supercapacitors was carried out at 125°C in an autoclave process. During the consolidation, in situ characterisations of the capacitors are performed, prove to be very sensitive to temperature changes. This information is used during the space qualification, especially during thermal vacuum chamber tests (-22°C to +67°C) in order to expand the whole system by thermal sensing ability, creating further weight and volume reduction because no additional sensors are needed.