The work constitutes the fabrication of low-cost, simple, novel, and environmentally friendly printed energy storage devices. These can be supercapacitors and polymer electrolytic capacitors for wearable and flexible energy storage applications like energy-autonomous and distributed electronics platforms.
The scaling and design of dual cell supercapacitor and use of organic electrolyte to achieve high electrochemical potential window. The practical demonstration of supercapacitors that provide peak power to operate Bluetooth low energy modules can be operated at temperature ranges from -40°C to 100°C. Similarly, the polymer electrolytic capacitor is modelled for low-pass filtering and smoothing applications.
In addition, green and clean energy harvesting from ambient energy sources such as indoor light and pressure was demonstrated. This increases energy efficiency and minimises greenhouse gas emissions (CO2) and reduces global warming. The energy harvesters used in this research are organic photovoltaic (OPV), and a piezoelectric transducer integrated with energy storage devices. The maximum energy harvested in supercapacitors was about 39 mJ.
Energy storage under extreme conditions is challenging and investigated by systematic reliability testing
Reliability testing, including the determination of failure mechanisms, is very important, due to energy storage demand in the harsh environment, and is widely applied to power electronics systems and devices.
The mechanical and thermal stability of the supercapacitors was surprisingly good. The organic electrolyte-based supercapacitor shows a high degree of flexibility up to bending radii of 4 mm and works at different temperature ranges. Similarly, polymer electrolytic capacitor shows promising results during thermal and bending test.
In particular, the mechanical robustness and wide temperature range are important for numerous applications, including the smart ski sport demonstrator into which the devices were integrated; the devices need to withstand elevated temperatures for lamination, and work at low temperatures when on the ski slope. The thermal shock gives essential information device's behaviour and is the first systematic reliability study on this type of device.
The doctoral dissertation of Msc. Chakra Rokaya in the field of electronics engineering titled Printed energy storage for energy autonomous flexible electronics will be publicly examined in the Faculty of Information Technology and Communication Sciences at Tampere University, Hervanta campus, in the auditorium TB109 of Tietotalo, Korkeakoulunkatu 1, on the 9th of December 2022, at 12 o’clock. at Tampere. The Opponent will be Professor Leif Nyholm, Uppsala University, Sweden. The Custos will be Professor Donald Lupo, Tampere University.
The dissertation is available online.
Photo: Bikram Thapa