Doctoral defence: Maarja Paalo “Synthesis and characterization of novel carbon electrodes for high power density electrochemical capacitors”

On 29 March at 12:15 Maarja Paalo will defend her doctoral thesis “Synthesis and characterization of novel carbon electrodes for high power density electrochemical capacitors”.

Supervisors:
Associate Professor Thomas Thomberg, University of Tartu
Indrek Tallo, Concise Systems OÜ
Professor Enn Lust, University of Tartu

Opponent:
Associate Professor Olivier Crosnier, University of Nantes (France)

Summary
In recent years, the demand for versatile energy storage systems has risen quite fast. The environmental impact of energy consumption for some regions has additionally increased the necessity for new energy storage devices with high power and energy densities. Supercapacitors have gained much attention because they have high specific capacitance, long cycle life, high power density, and very low maintenance costs. Supercapacitors complement batteries and fuel cells in applications where high power is important. The energy storage and power delivery characteristics of supercapacitors are largely determined by the electrical capacitance, system resistance, and maximum cell potential which are all dependent on the electrode materials porosity and electrolyte properties used. One of the most used electrode materials in supercapacitors are different carbide derived carbons, which have the possibility to fine-tune the pore size. One limiting factor in achieving high power density is the moderate working cell potential of different electrolytes that are used in supercapacitors. To achieve excellent performance of a supercapacitor it is important to optimize the electrode’s micro-mesoporosity and for the used electrolyte, it is important that it has a high electrochemical window and that the electrolyte ions suit the selected electrode material.

In this thesis, firstly, a sol-gel method was used for the preparation of well developed micro- and mesoporous electrodes, which gives additional mesoporosity to the initial carbide material. This results also in the derived carbon material, unlike when the commercially synthesized titanium carbide is used. Secondly, the operando activation and passivation method was developed for future enlargement of the ideal polarizability region of electrodes, to achieve higher energy densities.

The defence will be held in MS Teams.