The need for large-scale energy storage, preferably electric, is increasing in line with the expansion of renewables energy production. With an increased share of solar energy and wind power with intermittent electricity production so will electrical energy storage to e.g. cut power peaks to become increasingly significant. Pumped power plants are already in use and expansion of compressed air storage is taking place in various parts of the world. The there are also great expectations for battery technology and hydrogen storage in the future. Hydrogen storage means some losses, both during electrolysis and conversion to electricity in a fuel cell, which is a disadvantage this technique. Today’s Li-ion batteries still cost too much, especially if you count the cost per unit kWh and cycle. The climate burden is also great for the batteries that are the best in terms of cost. An interesting battery solution is supercapacitors that can be manufactured from renewable materials. Although they only reach 5-10% of the energy density of Li-ion batteries, the increased size is compensated for so-called “electrical double layer (EDL) supercapacitors” of a much longer lifetime, > 10 times and a higher current density, about 10 times. By electrical double layers is meant non-chemical energy storage where the ions of the electrolyte are electrostatically bound in a double layer against the electrode which typically consists of porous activated carbon. There are still many question marks surrounding EDL supercapacitors in applications such as large-scale electrical energy storage and many concern the optimization of the porosity of the electrode relative to it selected electrolyte ions to create a cost- and performance-competitive product. In this degree project, you will evaluate various processes for producing activated carbon with large specific surface area. A larger specific surface enables greater energy density, however with the right ions in it the electrolyte. An important part is to investigate how the KOH used to increase the specific surface area can be recycled in a cost-effective manner. Another important part is to examine how the share electrolyte in the supercapacitor can be minimized to both reduce costs and increase the specific the energy. The experimental parts of the project are:
- Pyrolyze and activate biomass
- Recycle KOH
- Build electrode structures
- Build supercapacitor cells
- Evaluate performance of fabricated supercapacitors
The degree project is based on a thorough literature study and summarized in a well-written report. The experimental parts takes place in dedicated premises for the various project stages. You should have studied materials science and/or chemistry. The work offered during the spring semester 2023 starting no later than February. Contact Stefan Johansson, email@example.com for more information.